Author Topic: NASA's Trappist-1 Announcement - Feb 22, 2017  (Read 26305 times)

Offline Apollo-phill

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NASA's Trappist-1 Announcement - Feb 22, 2017
« on: 02/20/2017 07:43 PM »
One participant is Michael Gillon,astronomer t University of Liege.

This latterinstitution has/said they disdcovered three Earth sized planet round a small star 40 light years away .

Is this the NASA announcemen on 22 Feb 2017 ?

« Last Edit: 03/13/2017 12:31 PM by Chris Bergin »

Offline Kosmos2001

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Offline Star One

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I provide the link with the official announcement: https://www.nasa.gov/press-release/nasa-to-host-news-conference-on-discovery-beyond-our-solar-system

Preview article with no spoilers so to speak.

https://www.cnet.com/news/nasa-space-exoplanet-preview-sara-seager/

Though it does come with an interesting illustration.
« Last Edit: 02/20/2017 08:40 PM by Star One »

Offline as58

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Probably something to do with TRAPPIST-1, my guess would be something about atmospheres of the planets. This Spitzer proposal abstract may give a hint (http://adsabs.harvard.edu/abs/2016sptz.prop13067G):

Quote
The recently detected TRAPPIST-1 planetary system represents a unique opportunity to extend the nascent field of comparative exoplanetology into the realm of temperate terrestrial worlds. It is composed of at least three Earth-sized planets similar in sizes and irradiations to Earth and Venus transiting an ultra-cool dwarf star only 39 light-years away. Thanks to the Jupiter-size and infrared brightness of their host star, the planets are amenable for detailed atmospheric characterization with JWST, including for biosignatures detection. Our Spitzer Exploration Science Program aims to prepare and optimize the detailed study of this fascinating planetary system through the two following complementary sub-programs: (1) a 480 hrs continuous monitoring of the star to explore its full inner system up to its ice line in a search for any other transiting object(s) (planet, moon, Trojan) with a sensitivity high enough to detect any body as small as Ganymede, and (2) the observation of ~130 transits of the planets (520 hrs). This second part has two goals. First, to measure precisely the planets' masses and eccentricities through the Transit Timing Variations method, to constrain strongly their compositions and energy budgets. Secondly, to measure with an extremely high precision the planets' effective radii at 4.5 microns to assess, when combined with future HST/WFC3 observations, the presence of an atmosphere around them. The two complementary parts of this program will make it a long-lasting legacy of Spitzer to the fields of comparative exoplanetology and astrobiology, by providing the necessary measurements on the inner system of TRAPPIST-1 (complete census, masses, eccentricities, first insights on atmospheres) required to initiate and optimize the detailed atmospheric characterization of its different components with JWST and other future facilities.

As always, a press conference and embargo don't necessarily mean anything very major. There seems to be quite a bit of randomness to what gets promoted.

Offline Star One

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Some big hitters for a minor announcement as the article I linked to points out?
« Last Edit: 02/20/2017 08:49 PM by Star One »

Offline as58

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Hmm, it's a real press conference with all those people present and not just a telecon, so I agree that it looks to be something at least 'majorish'. It's probably also something the interests general public, because otherwise they wouldn't bother with the AMA. My guess is something nice about TRAPPIST-1 planets' atmospheres, although it's not to me clear how much they could see with warm Spitzer (only NIR photometry and no spectroscopy available). Exoplanets is  not my field, though.

Offline Star One

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Hmm, it's a real press conference with all those people present and not just a telecon, so I agree that it looks to be something at least 'majorish'. It's probably also something the interests general public, because otherwise they wouldn't bother with the AMA. My guess is something nice about TRAPPIST-1 planets' atmospheres, although it's not to me clear how much they could see with warm Spitzer (only NIR photometry and no spectroscopy available). Exoplanets is  not my field, though.

It's certainly already picked up a lot of traction on Twitter for what that's worth.

Offline Alpha_Centauri

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Interesting.

This is the recent HST observation request regarding atmosphere observations mentioned in the paper above;

http://www.stsci.edu/hst/phase2-public/14873.pdf
Quote
ABSTRACT
Owing to over 1500 hours of monitoring including a recent 20-d long follow-up with the Spitzer Space Telescope, we have now constrained the architecture of TRAPPIST-1's system up to its ice line. There is no doubt left regarding the system uniqueness for Earth-sized comparative planetology and for the search for extrasolar habitats. The present request for DDT will fulfill the urgent need to inform the community about TRAPPIST-1 planets in order to guide their follow-up, notably in the context of the upcoming JWST Cycle 1 proposal. We request 23 HST/WFC3 orbits to assess the presence of extended atmospheres.

OBSERVING DESCRIPTION
We propose to observe the transits of TRAPPIST-1's planets with WFC3 on Dec.4, Dec. 29, and Jan. 10 to obtain their tansmission spectra and assess the presence of extended atmospheres.

I agree it most likely is regarding detection of atmospheres.

Edit; also http://www.stsci.edu/hst/phase2-public/14900.pdf

Quote

ABSTRACT
We have recently completed reconnaissance studies of the TRAPPIST-1 system with the Spitzer and Hubble Space Telescopes. Owing to a 20-d long follow-up with Spitzer, we have now constrained the system architecture up to the ice line. Thanks to 4 non-consecutive HST/STIS orbits, we have determined the potential for further studies of the system in the UV--notably to search for hydrogen exospheres--and characterized the UV environment of TRAPPIST-1's planets, which is an essential contributing factor to their potential habitability. These reconnaissance studies with the synergetic Great Observatories emphasize the system uniqueness for Earth-sized comparative planetology and for the search for extrasolar habitats.
We request here 5 consecutive HST/STIS orbits to build upon our UV exploratory program and confirm the presence of an extended exosphere exosphere around TRAPPIST-1~c. These observations will inform us on its volatile reservoir while complementing the insights gained with HST/WFC3 (GOs 14500 and 14873). Our request for immediate HST/STIS followup will fulfill the urgent need to inform the community about TRAPPIST-1 planets in order to guide their follow-up, notably in the context of the upcoming JWST Cycle 1 proposal.

OBSERVING DESCRIPTION
We propose to observe the transits of TRAPPIST-1's planets with WFC3 on Dec.4, Dec. 29, and Jan. 10 to obtain their tansmission spectra and assess the presence of extended atmospheres.
« Last Edit: 02/21/2017 08:54 AM by Alpha_Centauri »

Offline CuddlyRocket

I agree it most likely is regarding detection of atmospheres.

Generally, they sell these things to the general public on the possibilities for extra-terrestrial life. So, perhaps they've discovered an exoplanet in the habitable zone with an oxygen-laden atmosphere? Even more interesting if they can rule out any of the non-biological mechanisms for producing an oxygen-laden atmosphere!

Offline Alpha_Centauri

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I doubt it is that big, for a start Hubble likely doesn't have the sensitivity to make an oxygen detection.  This is the last Nasa press release regarding Hubble looking for atmospheres on the Trappist planets;

https://www.nasa.gov/press-release/nasa-s-hubble-telescope-makes-first-atmospheric-study-of-earth-sized-exoplanets

Quote
“With more data, we could perhaps detect methane or see water features in the atmospheres, which would give us estimates of the depth of the atmospheres,” said Hannah Wakeford, the paper’s second author, at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Observations from future telescopes, including NASA’s James Webb Space Telescope, will help determine the full composition of these atmospheres and hunt for potential biosignatures, such as carbon dioxide and ozone, in addition to water vapor and methane. Webb also will analyze a planet’s temperature and surface pressure – key factors in assessing its habitability.
« Last Edit: 02/21/2017 10:10 AM by Alpha_Centauri »

Offline Star One

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Is there still observing time up for grabs on JWST in its initial observing campaigns or has this already been allocated?

Offline Star One

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Offline as58

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Is there still observing time up for grabs on JWST in its initial observing campaigns or has this already been allocated?

Director's Discretionary Early Release Science deadline has not passed yet.

Offline Star One

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Is there still observing time up for grabs on JWST in its initial observing campaigns or has this already been allocated?

Director's Discretionary Early Release Science deadline has not passed yet.

Could this amongst other things be a way of strengthening an application for time on it?

Offline as58

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I doubt it is that big, for a start Hubble likely doesn't have the sensitivity to make that sort of detection.  This is the last Nasa press release regarding Hubble looking for atmospheres on the Trappist planets;

https://www.nasa.gov/press-release/nasa-s-hubble-telescope-makes-first-atmospheric-study-of-earth-sized-exoplanets

Quote
“With more data, we could perhaps detect methane or see water features in the atmospheres, which would give us estimates of the depth of the atmospheres,” said Hannah Wakeford, the paper’s second author, at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Observations from future telescopes, including NASA’s James Webb Space Telescope, will help determine the full composition of these atmospheres and hunt for potential biosignatures, such as carbon dioxide and ozone, in addition to water vapor and methane. Webb also will analyze a planet’s temperature and surface pressure – key factors in assessing its habitability.

I'm thinking it's transmission spectrum detection of some constituent of atmosphere of some/one of TRAPPIST-1 planet(s). I don't think that has been done with ~Earth-sized planets before.

Offline as58

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Is there still observing time up for grabs on JWST in its initial observing campaigns or has this already been allocated?

Director's Discretionary Early Release Science deadline has not passed yet.

Could this amongst other things be a way of strengthening an application for time on it?

Certainly, spectroscopic characterisation of exoplanets is one of JWST main science themes. Note though that DDERS is a special call which comes with requirements for speedy release of data and such, so it's not given that everyone wants to apply for it.

Offline Alpha_Centauri

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I'm thinking it's transmission spectrum detection of some constituent of atmosphere of some/one of TRAPPIST-1 planet(s). I don't think that has been done with ~Earth-sized planets before.

Indeed, the identification of any constituent would be a first for an Earth-sized planet. Water vapour might be especially interesting if they could put constraints on a surface source.  I say water vapour as the UV observations requested are particularly useful for water vapour detection.
« Last Edit: 02/21/2017 11:29 AM by Alpha_Centauri »

Offline jebbo

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I'm thinking it's transmission spectrum detection of some constituent of atmosphere of some/one of TRAPPIST-1 planet(s). I don't think that has been done with ~Earth-sized planets before.

TRAPPIST-1 was my bet as well ... transmission spectroscopy would be great (and no, I can't think of any previous Earth/super-Earth results, or even any "warm" rather than "hot" results). So, *really* exciting things would be any of:
- water vapour
- measurement of atmosphere scale height
- of "d" for added excitement (close to HZ and all that).

It feels too dim for reflective spectroscopy and cloud maps, etc.

I also wonder if they have early data from K2 campaign 12 (TRAPPIST-1 is a target, but the campaign doesn't end until 4 March).

Edit: RV data would also be useful - pins down mass & density. But I don't see any representation from suitable instruments.

Edit2: if there is K2 transit photometry, TTVs / TDVs might also pin down mass / density, though I'm not sure we could break the degeneracy.

--- Tony
« Last Edit: 02/21/2017 10:26 AM by jebbo »

Offline Alpha_Centauri

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Gillon has been monitoring TRAPPIST-1 with Hawk-I at the VLT, among others.

I assume with the relatively long baseline they have they may be able to get TTVs to derive the masses.
« Last Edit: 02/21/2017 10:28 AM by Alpha_Centauri »

Offline Ben the Space Brit

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Shooting blindly into the dark, maybe they have some indication of near-me planets in Earth-type orbits around K- or G-class stars in the immediate galactic neighbourhood from the detailed radial velocity measurements that they've been taking recently. I know that Epsilon Erandi is considered a good candidate.
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Offline jebbo

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Shooting blindly into the dark, maybe they have some indication of near-me planets in Earth-type orbits around K- or G-class stars in the immediate galactic neighbourhood from the detailed radial velocity measurements that they've been taking recently. I know that Epsilon Eridani is considered a good candidate.

This doesn't sound like an RV related announcement, but there is an additional potentially habitable planet due for announcement on Thursday (under embargo) that is unrelated which may well be from RV.

--- Tony

Offline Alpha_Centauri

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It is about TRAPPIST-1, definitely.

This is from the famous Didier Queloz, who has worked with Gillon;

https://www.twitter.com/DidierQueloz/status/833976887500234754

https://www.twitter.com/DidierQueloz/status/834027647046918145

It will probably be an announcement one of the planets is likely a waterworld.

Edit; Looks like he's hidden the tweets.
« Last Edit: 02/21/2017 04:48 PM by Alpha_Centauri »

Offline jebbo

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It is about TRAPPIST-1, definitely.

This is from the famous Didier Queloz, who has worked with Gillon;

https://www.twitter.com/DidierQueloz/status/833976887500234754

https://www.twitter.com/DidierQueloz/status/834027647046918145

It will probably be an announcement 1c is likely a waterworld.

How was I not following Didier? Doh!

--- Tony

Offline Star One

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Am I right in thinking that the HST is insufficiently sensitive to detect free oxygen in the atmosphere and they will have to wait for JWST to come on line to do this?

Online FutureSpaceTourist

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Quote
#NASA will announce that TRAPPIST-1 has 7 Earth-sized planets - 6 within/close to star's habitable zone #astrobiology #extrasolar #astronomy

https://twitter.com/NASAWatch/status/834084255923838976
« Last Edit: 02/21/2017 04:04 PM by FutureSpaceTourist »

Offline Alpha_Centauri

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That looks to me pure speculation, and I'm not convinced;

http://nasawatch.com/archives/2017/02/spitzer-discove.html

It is not impossible there are other bodies, indeed earlier proposals remarked on other potential transit features not related to the already identified planets.  But if they had found other objects I suspect they would have been mentioned in the most recent proposals, even if obliquely.

I also don't see why representatives of both Spitzer and Hubble would need to be there. They could be identified by the search conducted at the VLT alone.
« Last Edit: 02/21/2017 04:31 PM by Alpha_Centauri »

Offline as58

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That looks to me pure speculation, and I'm not convinced;

http://nasawatch.com/archives/2017/02/spitzer-discove.html

It is not impossible there are other bodies, indeed earlier proposals remarked on other potential transit features not related to the already identified planets.  But if they had found other objects I suspect they would have been mentioned in the most recent proposals, even if obliquely.

I also don't see why representatives of both Spitzer and Hubble would need to be there.

Also "just" finding more planets doesn't feel to me quite exciting enough for the press conference.

Offline Star One

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That looks to me pure speculation, and I'm not convinced;

http://nasawatch.com/archives/2017/02/spitzer-discove.html

It is not impossible there are other bodies, indeed earlier proposals remarked on other potential transit features not related to the already identified planets.  But if they had found other objects I suspect they would have been mentioned in the most recent proposals, even if obliquely.

I also don't see why representatives of both Spitzer and Hubble would need to be there.

Also "just" finding more planets doesn't feel to me quite exciting enough for the press conference.

They wouldn't have so many exoplanet atmosphere experts on the panel either.

Offline Alpha_Centauri

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Though if there are more planets, and there are more simultaneous transits like the double-transit between b and c, there could be opportunities for higher signal-to-noise transmission spectroscopy studies than might otherwise be the case.

Am I right in thinking that the HST is insufficiently sensitive to detect free oxygen in the atmosphere and they will have to wait for JWST to come on line to do this?

That is my understanding, but no doubt i'll be proved wrong.
« Last Edit: 02/21/2017 05:41 PM by Alpha_Centauri »

Offline jebbo

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That looks to me pure speculation, and I'm not convinced;

I'm not at all convinced. From reading his "source" documents I think he has got confused over HST orbit planning ... and as as58 says, it really doesn't account for the panel composition or the excitement (heck, I've found a 7 planet system; well, helped to :-) )

--- Tony

Offline Star One

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That looks to me pure speculation, and I'm not convinced;

I'm not at all convinced. From reading his "source" documents I think he has got confused over HST orbit planning ... and as as58 says, it really doesn't account for the panel composition or the excitement (heck, I've found a 7 planet system; well, helped to :-) )

--- Tony

It's not impossible that they'll also announce more planets in the system as well. If it was 7 I think that would make it the most heavily populated exo planet solar system.

Offline jebbo

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It's not impossible that they'll also announce more planets in the system as well. If it was 7 I think that would make it the most heavily populated exo planet solar system.

True ... however Kepler-90 (KOI-351) has 7 and HD 10180 has at least 7 and possibly nine, so while unusual, I doubt it would warrant the amount of excitement we're seeing.

Edit: also, if there are additional *transiting* planets, I'd expect them to wait for the K2 campaign 12 release ...

--- Tony
« Last Edit: 02/21/2017 06:06 PM by jebbo »

Offline Bynaus

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It's not impossible that they'll also announce more planets in the system as well. If it was 7 I think that would make it the most heavily populated exo planet solar system.

True ... however Kepler-90 (KOI-351) has 7 and HD 10180 has at least 7 and possibly nine, so while unusual, I doubt it would warrant the amount of excitement we're seeing.

--- Tony

I think the excitement - if the rumors are true - would come from the suggestion that 6 of these 7 Earth-sized worlds are in the habitable zone. That would indeed be very interesting, as we could probe how increasing irradiation by the star affects their atmospheres, making that star something of a "Rosetta stone" for Earth-size-exoplanet atmosphere studies.
« Last Edit: 02/21/2017 06:08 PM by Bynaus »

Offline Star One

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It's not impossible that they'll also announce more planets in the system as well. If it was 7 I think that would make it the most heavily populated exo planet solar system.

True ... however Kepler-90 (KOI-351) has 7 and HD 10180 has at least 7 and possibly nine, so while unusual, I doubt it would warrant the amount of excitement we're seeing.

Edit: also, if there are additional *transiting* planets, I'd expect them to wait for the K2 campaign 12 release ...

--- Tony

I meant extra planets and atmosphere announcements?

Offline Alpha_Centauri

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Apparently it is true (I think someone has got their embargo dates wrong);

http://uk.businessinsider.com/earth-size-worlds-seven-trappist-1-2017-2?r=US&IR=T

Offline jebbo

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I think the excitement - if the rumors are true - would come from the suggestion that 6 of these 7 Earth-sized worlds are in the habitable zone. That would indeed be very interesting, as we could probe how increasing irradiation by the star affects their atmospheres, making that star something of a "Rosetta stone" for Earth-size-exoplanet atmosphere studies.

Fair point, and yes, it would definitely be a fantastic test-bed for atmosphere studies!  Personally, I'd still expect them to wait for the campaign 12 data though as it feels unlikely there was enough HST time to well characterise the orbits of 4 presumably longer period candidates.

I guess we'll know in <24 hours.  Exciting stuff!!

Edit: it seems I'm wrong! 

--- Tony
 
« Last Edit: 02/21/2017 06:19 PM by jebbo »

Offline Star One

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Apparently it is true (I think someone has got their embargo dates wrong);

http://uk.businessinsider.com/earth-size-worlds-seven-trappist-1-2017-2?r=US&IR=T

Why all the atmosphere experts then? Feels like there should be more to this announcement.

Offline Bubbinski

Might they be announcing both 7 planets and exciting atmosphere results? I'll be tuned in tomorrow!
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline jebbo

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Why all the atmosphere experts then? Feels like there should be more to this announcement.

There clearly is ... the article gives masses for all but "h", so I think they've seen TTVs.  Also, as Bynaus points out, the system is a great laboratory for atmosphere studies.  Probably, the Spitzer and HST campaigns will have put constraints on possible atmospheres as well ...

Anyway, very very exciting! And I'll bet it guarantees Trappist-1 a very early JWST observing slot :-)

Edit: the planets are also resonant:
- d 5:3 resonance w/ c
- e 3:2 resonance w/ d
- f ~3:2 resonance w/ e; ~6:1 resonance w/ b
- g ~4:3 resonance w/ g

--- Tony
« Last Edit: 02/21/2017 07:04 PM by jebbo »

Offline ugordan

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Apparently it is true (I think someone has got their embargo dates wrong);

http://uk.businessinsider.com/earth-size-worlds-seven-trappist-1-2017-2?r=US&IR=T

I'm looking at the animated light curve in that article and wondering what's up with that photon count spike immediately before one of the transits of "b"?

It can't be an atmospheric refraction effect, can it, because it would have been seen with other transits as well. Maybe it's a flare event on the star itself, but the timing seems suspect...

Offline Alpha_Centauri

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It could be a flare, but from my experience with Kepler data I would say most likely it is an artifact of the lightcurve processing correcting for the spacecraft pointing.
« Last Edit: 02/21/2017 07:04 PM by Alpha_Centauri »

Offline Star One

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A little more detail here.

Quote
It is possible that most of the planets confirmed thus circling far TRAPPIST-1 could be in the star's habitable zone. The inner 6 planets are probably rocky in composition and may be just the right temperature for liquid water to exist (between 0 - 100 degrees C) - if they have any water, that is. The outermost 7th planet still needs some more observations to nail down its orbit and composition.

http://spaceref.com/exoplanets/nearby-star-has-7-earth-sized-worlds---most-in-habitable-zone.html

By the way the Business Insider article now brings up a 404 error so someone must have told them they jumped the gun.
« Last Edit: 02/21/2017 09:18 PM by Star One »

Offline Ben the Space Brit

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I appreciate the excitement in scientific circles but, as I understand it, TRAPPIST-1 only barely classifies above a Brown Dwarf. That makes for very tight orbits to make for a thermal 'goldilocks zone'.

The problem I've always had with these dim red dwarf 'habitable zone' planets is that all the other physical characteristics are likely to make them sterile, most notably being tidally locked, really close to the photosphere (and thus likely to be bathed in lethal X- and UV-radiation levels) and probably without atmosphere due to lack of magnetic field )due to said tidal locking) and close proximity to the primary.

They make for useful studies and doubtless have their own unique charms (Pluto has taught us that there is no such thing as an 'uninteresting planetary body'). I guess I just have difficulty hyping these bodies up in my mind.

In my mind, with current sensing capabilities, the optimum habitable target world we're likely to find would be a hypothetical Galilean Moon-sized object orbiting a detected 'Warm Jupiter' in the habitable zone of a K- to A-class primary.
« Last Edit: 02/22/2017 10:51 AM by Ben the Space Brit »
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Offline Alpha_Centauri

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While I empathise the fact is the vast majority of stars are closer in scale to TRAPPIST-1 than to our own relatively large star. We need to understand just how habitable they may be. The fact is we have no real idea of how the conditions affect habitability. Remember, no one believed we would find much life at the bottom of the oceans , far from sunlight, until we went there and found hydrothermal vents. For all we know there could be exofish swimming happily a few meters beneath the surface on a waterworld here, easily protected from the X-Ray flux.

Anyway, b and f look interesting; they would appear possibly volatile-rich given the densities. b in particular could be steamy.
« Last Edit: 02/22/2017 12:34 PM by Alpha_Centauri »

Offline Star One

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I appreciate the excitement in scientific circles but, as I understand it, TRAPPIST-1 only barely classifies above a Brown Dwarf. That makes for very tight orbits to make for a thermal 'goldilocks zone'.

The problem I've always had with these dim red dwarf 'habitable zone' planets is that all the other physical characteristics are likely to make them sterile, most notably being tidally locked, really close to the photosphere (and thus likely to be bathed in lethal X- and UV-radiation levels) and probably without atmosphere due to lack of magnetic field )due to said tidal locking) and close proximity to the primary.

They make for useful studies and doubtless have their own unique charms (Pluto has taught us that there is no such thing as an 'uninteresting planetary body'). I guess I just have difficulty hyping these bodies up in my mind.

In my mind, with current sensing capabilities, the optimum habitable target world we're likely to find would be a hypothetical Galilean Moon-sized object orbiting a detected 'Warm Jupiter' in the habitable zone of a K- to A-class primary.

Actually TRAPPIST-1 one is a pretty quiet star as red dwarfs go so the issue of the planets being bathed in lethal radiation may be somewhat mitigated.

Anyway being as they are currently the only planets that we will be able to spectroscopical examine with current technology I am not sure such a downbeat response is warranted when nature provides such a fine exo solar system close at hand.
« Last Edit: 02/22/2017 12:58 PM by Star One »

Offline jebbo

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Anyway, b and f look interesting; they would appear possibly volatile-rich given the densities. b in particular could be steamy.

I doubt "b" ... given the resonances, I expect it's Io-like due to tidal heating. On the plus side, this means those nearer the ice line may be warmer than just flux would suggest, though I haven't run any numbers.

On planets around M dwarfs in general, like Ben, I'm sceptical due to both locking and desiccation when the stars are young.

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Offline ugordan

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Given the apparent orbital resonances, is it at all plausible that some of those planets might not be tidally locked to the star, but instead ended up in a kind of resonant rotation similar to Mercury?

Offline Star One

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Anyway, b and f look interesting; they would appear possibly volatile-rich given the densities. b in particular could be steamy.

I doubt "b" ... given the resonances, I expect it's Io-like due to tidal heating. On the plus side, this means those nearer the ice line may be warmer than just flux would suggest, though I haven't run any numbers.

On planets around M dwarfs in general, like Ben, I'm sceptical due to both locking and desiccation when the stars are young.

--- Tony

Is that all we're going to do be downbeat about this, no wonder those in society who devalue science are having so much success these days.

Offline jebbo

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Is that all we're going to do be downbeat about this, no wonder those in society who devalue science are having so much success these days.

Why do you think this is downbeat? I'm sceptical over the habitability of planets around M dwarfs. That doesn't make them uninteresting or even mean there aren't plenty of habitable planets around other types of star.

It also doesn't mean I'm ruling it out, just that there are good reasons to doubt that just because a planet is in the HZ means it is at all close to being Earth-like or habitable.  Much depends on system formation, and most models don't allow enough volatiles for atmosphere / water to survive the initial flare activity.

--- Tony


Offline whitelancer64

I appreciate the excitement in scientific circles but, as I understand it, TRAPPIST-1 only barely classifies above a Brown Dwarf. That makes for very tight orbits to make for a thermal 'goldilocks zone'.

The problem I've always had with these dim red dwarf 'habitable zone' planets is that all the other physical characteristics are likely to make them sterile, most notably being tidally locked, really close to the photosphere (and thus likely to be bathed in lethal X- and UV-radiation levels) and probably without atmosphere due to lack of magnetic field )due to said tidal locking) and close proximity to the primary.

They make for useful studies and doubtless have their own unique charms (Pluto has taught us that there is no such thing as an 'uninteresting planetary body'). I guess I just have difficulty hyping these bodies up in my mind.

In my mind, with current sensing capabilities, the optimum habitable target world we're likely to find would be a hypothetical Galilean Moon-sized object orbiting a detected 'Warm Jupiter' in the habitable zone of a K- to A-class primary.

Just to correct a misconception: Venus has an extensive atmosphere and no magnetic field, so we know that magnetic fields are not a prerequisite for having or maintaining an atmosphere.

Venus and the Earth hold on to their atmospheres primarily by gravity - Nitrogen and Oxygen are too heavy to escape Earth's gravity, though we do lose lighter molecules like Hydrogen and Helium, primarily through solar heating of the exosphere which energizes those molecules to escape velocity, a process called Jeans Escape.

https://en.m.wikipedia.org/wiki/Atmospheric_escape

The exoplanets around TRAPPIST-1 are almost all very nearly the same mass or slightly more massive than the Earth, so we should expect they would be likely to have an atmosphere.
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Offline jebbo

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The exoplanets around TRAPPIST-1 are almost all very nearly the same mass or slightly more massive than the Earth, so we should expect they would be likely to have an atmosphere.

Sadly, that is too optimistic ... there have been a number of studies of both water and atmosphere loss from planets around late M dwarfs, and they give a pretty pessimistic outlook. The three most pertinent are:

On water loss: https://arxiv.org/abs/1605.00616
On atmosphere loss: https://arxiv.org/abs/1702.03386
On both: http://iopscience.iop.org/article/10.3847/2041-8213/836/1/L3

[ The final one is unfortunately behind a paywall ]

A lot depends on the initial conditions, on migration, and on later volatile delivery ... so not ruled out, but also not a given.  On the plus side, Trappist-1 is an almost perfect test bed for this!  All very exciting.

--- Tony


Offline Alpha_Centauri

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Anyway, b and f look interesting; they would appear possibly volatile-rich given the densities. b in particular could be steamy.

I doubt "b" ... given the resonances, I expect it's Io-like due to tidal heating. On the plus side, this means those nearer the ice line may be warmer than just flux would suggest, though I haven't run any numbers.

I don't know, an "Io" approximately the radius of Earth should be considerably more dense.

Anyway hopefully there'll be some constraints mentioned in the announcements.

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Offline Star One

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Is that all we're going to do be downbeat about this, no wonder those in society who devalue science are having so much success these days.

Why do you think this is downbeat? I'm sceptical over the habitability of planets around M dwarfs. That doesn't make them uninteresting or even mean there aren't plenty of habitable planets around other types of star.

It also doesn't mean I'm ruling it out, just that there are good reasons to doubt that just because a planet is in the HZ means it is at all close to being Earth-like or habitable.  Much depends on system formation, and most models don't allow enough volatiles for atmosphere / water to survive the initial flare activity.

--- Tony

Fair enough.

Did I imagine it or did I read that they had spent 1500h observing this system using the HST.

Offline as58

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Did I imagine it or did I read that they had spent 1500h observing this system using the HST.

I missed the article when it was up, but there's no way they could've gotten anywhere close to that number of hours.

edit: I think 1500 hours refers to total time with all telescopes including Spitzer, on which they did get several hundred hours. A quick look at accepted proposals shows about 40 orbits of HST observations.
« Last Edit: 02/22/2017 03:55 PM by as58 »

Offline Star One

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Did I imagine it or did I read that they had spent 1500h observing this system using the HST.

I missed the article when it was up, but there's no way they could've gotten anywhere close to that number of hours.

edit: I think 1500 hours refers to total time with all telescopes including Spitzer, on which they did get several hundred hours. A quick look at accepted proposals shows about 40 orbits of HST observations.

Thanks for that clarification. That's why I asked as it was likely I had misremembered.

Offline jebbo

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edit: I think 1500 hours refers to total time with all telescopes including Spitzer, on which they did get several hundred hours. A quick look at accepted proposals shows about 40 orbits of HST observations.

The HST proposal at http://www.stsci.edu/hst/phase2-public/14873.pdf says:

Quote
Owing to over 1500 hours of monitoring including a recent 20-d long follow-up with the Spitzer Space Telescope, we have now constrained the architecture of TRAPPIST-1's system up to its ice line

My assumption is the 1500 includes the TRAPPIST observations ... and presumably AO / spectroscopic followup.

--- Tony

Offline Star One

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Here's the article from Nature.

Quote
Other researchers are already using the Hubble Space Telescope to hunt for atmospheres on the TRAPPIST-1 planets. Kepler is also observing the system and will gather data that can better pin down the planetary masses, says Courtney Dressing, an astronomer at the California Institute of Technology in Pasadena. And the TRAPPIST team is building four new 1-metre-diameter telescopes in Chile to continue the work.

“For all the worlds that we see in science fiction, these are even more extraordinary,” says Hannah Wakeford, an exoplanet scientist at Goddard.

http://www.nature.com/news/these-seven-alien-worlds-could-help-explain-how-planets-form-1.21512

Quote
The Hubble Space Telescope characterized the atmospheres of TRAPPIST-1B and TRAPPIST-1C, finding that the two worlds probably aren't encircled by hydrogen and helium rich atmospheres, meaning their atmospheres could resemble our own.

Researchers will be able to get an even better look at these worlds in the future.

NASA's James Webb Space Telescope (JWST) — Hubble's telescope successor expected to launch in 2018 — should be able to peer deeply into the atmospheres of alien planets to try to see if they really could be like our own.

http://mashable.com/2017/02/22/seven-exoplanets-orbiting-trappist-1-star/
« Last Edit: 02/22/2017 05:16 PM by Star One »

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Offline Star One

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I've read in a few articles now that the fifth planet is considered the most habitable, why is this?
« Last Edit: 02/22/2017 06:53 PM by Star One »

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I think we've just found where firefly was set.

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I've read in a few articles now that the fifth planet is considered the most habitable, why is this?

From JPL

Quote
The TRAPPIST-1 system contains a total of seven planets, all around the size of Earth. Three of them -- TRAPPIST-1e, f and g -- dwell in their star's so-called "habitable zone."ť The habitable zone, or Goldilocks zone, is a band around every star (shown here in green) where astronomers have calculated that temperatures are just right -- not too hot, not too cold -- for liquid water to pool on the surface of an Earth-like world.

While TRAPPIST-1b, c and d are too close to be in the system's likely habitable zone, and TRAPPIST-1h is too far away, the planets' discoverers say more optimistic scenarios could allow any or all of the planets to harbor liquid water. In particular, the strikingly small orbits of these worlds make it likely that most, if not all of them, perpetually show the same face to their star, the way our moon always shows the same face to the Earth. This would result in an extreme range of temperatures from the day to night sides, allowing for situations not factored into the traditional habitable zone definition. The illustrations shown for the various planets depict a range of possible scenarios of what they could look like.
« Last Edit: 02/22/2017 07:08 PM by nacnud »

Offline as58

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Those brown, green, and blue zones in that TRAPPIST-1 system image seem to be IMO oddly placed. If we're looking just at irradiation and comparing to the Solar System, d should be easily inside the green zone, g well outside in the blue and f just about on the edge of green and blue. Or is there some more detail going into defining those zones (e.g. different stellar spectrum)?.
« Last Edit: 02/22/2017 07:29 PM by as58 »

Offline Star One

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Those brown, green, and blue zones in that TRAPPIST-1 system image seem to be IMO oddly placed. If we're looking just at irradiation and comparing to the Solar System, d should be easily inside the green zone, g well outside in the blue and f just about on the edge of green and blue. Or is there some more detail going into defining those zones (e.g. different stellar spectrum)?.

Everything I've read says that defining the habitable zone around an ultra cool dwarf is a tricky business so maybe it's related to that.

Offline Bynaus

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Yes, I think the runaway greenhouse limit for the smallest red dwarfs is around 0.9 S_Earth. So if scaled properly, the HZ is slightly further out for a smaller star. The paper preprint linked above says that they did climate models on all of them, and b, c, d ran into the runaway greenhouse state, while e, f, g remained temperate (h is likely too cold).

EDIT: if we are looking for a name for the system, I think we should call it ... ;)
« Last Edit: 02/22/2017 07:50 PM by Bynaus »

Offline jebbo

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Tidal heating may also be significant for the inner planets (and I like that they illustrate "b" with something rather Io-like).  Enough so that I know they got radio observing time (don't know the instrument) looking for exo-aurorae but sadly there was a galaxy in the FoV

On atmospheres, probably worth looking at where they lie on the "cosmic shoreline".
[ https://arxiv.org/abs/1702.03386 ]

Edit: the masses of all but "f" are poorly constrained as only from TTVs. So K2 c12 light curve will hopefully constrain them better.  Then we should have a better idea of the bulk properties.

--- Tony
« Last Edit: 02/22/2017 07:50 PM by jebbo »

Offline Star One

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From the NASA press release I love the travel poster for this system.

https://exoplanets.nasa.gov/system/resources/detail_files/2159_posternormalsize.jpg

I see Kepler is currently studying the system looking for more planets plus further defining these discovered planets. Also Spitzer is carrying out another observing campaign. It also sounds like this will be part of JWST's initial target list.
« Last Edit: 02/22/2017 07:51 PM by Star One »

Offline baldusi

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Yes, I think the runaway greenhouse limit for the smallest red dwarfs is around 0.9 S_Earth. So if scaled properly, the HZ is slightly further out for a smaller star. The paper preprint linked above says that they did climate models on all of them, and b, c, d ran into the runaway greenhouse state, while e, f, g remained temperate (h is likely too cold).

EDIT: if we are looking for a name for the system, I think we should call it ... ;)

In the press conference they stated that the spectrum of the star was significantly in the IR range, so the energy/spectrum distribution is quite different. And that's where the atmospheric effects, absorption lines etc would come into play.

Offline Star One

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Quote
Andrew LePage February 22, 2017 at 15:02
> In particular, let’s see what Andrew LePage comes up with in his own Habitable Zone Reality Check.

Well, I’ve got a lot of data to digest before a write a “Habitable Planet Reality Check” (hopefully to come out in the next few days), but at first blush there does indeed seem to be reason to believe that at least one of these worlds is “potentially habitable”… maybe more. And the fact that TRAPPIST-1e has a fairly well determined radius and mass with a resulting density suggestive of a volatile-rich planet means that Earth-size planets orbiting small red dwarfs *CAN* hold onto their water and atmospheres despite flare activity, excessive X-ray/XUV flux, etc.. That’s a hopeful sign about the potential habitability of exoplanets like Proxima Centauri b or even Kepler 186f, among many others.

From here.

http://www.centauri-dreams.org/?p=37199

Offline Lars-J

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Those brown, green, and blue zones in that TRAPPIST-1 system image seem to be IMO oddly placed. If we're looking just at irradiation and comparing to the Solar System, d should be easily inside the green zone, g well outside in the blue and f just about on the edge of green and blue. Or is there some more detail going into defining those zones (e.g. different stellar spectrum)?.

Since these planets are likely tidally locked (same face facing the star), the temperature extremes will be larger. So liquid water could exist on the dark side of a planet that would normally be too close to the start, and likewise liquid water could exist on a planet's star-facing side even if it is further out. That seems to explain the larger than normal "goldilocks zone".
« Last Edit: 02/22/2017 08:13 PM by Lars-J »

Offline jebbo

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On the  comment from Andrew Page, he means Trappist-1f, but his main point stands: at a density of 0.6 +/- 0.17 that of Earth, it does suggest a volatile rich planet .. but that is not guaranteed.

Instead, there could be a rocky core with an extended H/He envelope but the core mass is too low to get a significant envelope (current theory say >1.5-1.6 Me for this to happen), so I'd say this is low probability.

The really great thing is that we will probably be able to find out soon!

--- Tony

Offline sanman

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Lords of Kobol! Could it be the Great Colonies?  :o

Offline Star One

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Lords of Kobol! Could it be the Great Colonies?  :o

Well Kepler is looking for more planets and it only has to find five more.
« Last Edit: 02/22/2017 08:54 PM by Star One »

Offline Star One

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The Earth-like planets of Trappist-1 already appear in sci-fi

Scientists say they've found the best place to search for life beyond our solar system. The first science fiction story about it has already been published, in the journal Nature.

https://www.cnet.com/news/nature-science-fiction-trappist-1-nasa-planets-laurence-suhner/

Offline ThereIWas3

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I was wondering if the gravitational interactions between all these closely spaced planets could create sufficient tidal forces on the ones with liquid water to create tides.  Some theories think that ocean tides from Earth's Moon had a role in the evolution of life, due to the sloshing at the edges.
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NASA's press conference:


Offline Bynaus

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Arxiv preprint on UV / XUV and habitability in the Trappist-1 system. Long story short, if there is an Earth-like moderately dense atmosphere with an ozone layer - all good. That failing, not even UV-resistant bacteria can make it.

https://arxiv.org/abs/1702.06936

Offline sanman

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Arxiv preprint on UV / XUV and habitability in the Trappist-1 system. Long story short, if there is an Earth-like moderately dense atmosphere with an ozone layer - all good. That failing, not even UV-resistant bacteria can make it.

https://arxiv.org/abs/1702.06936

XRays won't penetrate far into the water - as long as you've got water oceans, you can have underwater life. Of course if you have that, then you probably have an atmosphere above it.

Offline CuddlyRocket

EDIT: if we are looking for a name for the system, I think we should call it ... ;)

[In the spirit of the suggestion. :) ]
Presumably you mean a name for the star? (TRAPPIST-1 is a catalog designation.) The system would then be called 'the [name of star] system'!

The IAU Working Group on Star Names might go for Axanar. The only two catalog designations I can find are 2MASS J23062928-0502285 and the later TRAPPIST-1 suggesting the star was discovered in the Two Micron All-Sky Survey of 1997-2001. So, there's unlikely to be any of the traditional or historical names for which the WGSN has a preference. The WGSN might object though if they consider a name from the title of a fan-made Star Trek movie to be a name of a principally commercial nature. Also, the film concerns the 'Battle of Axanar' and the WGSN also prohibit names related to military activities!

Offline Bynaus

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EDIT: if we are looking for a name for the system, I think we should call it ... ;)

[In the spirit of the suggestion. :) ]
Presumably you mean a name for the star? (TRAPPIST-1 is a catalog designation.) The system would then be called 'the [name of star] system'!

The IAU Working Group on Star Names might go for Axanar. The only two catalog designations I can find are 2MASS J23062928-0502285 and the later TRAPPIST-1 suggesting the star was discovered in the Two Micron All-Sky Survey of 1997-2001. So, there's unlikely to be any of the traditional or historical names for which the WGSN has a preference. The WGSN might object though if they consider a name from the title of a fan-made Star Trek movie to be a name of a principally commercial nature. Also, the film concerns the 'Battle of Axanar' and the WGSN also prohibit names related to military activities!

Yes, the name of the star. Although, I was not thinking of "Axanar" as a name (that might be an idea too!), its just that from the first moment "many planets, all habitable" somehow rang a bell - until I remembered where I had heard the phrase before. At the time-index I linked (or tried to link), they talk of the "Inverness" system, five inhabited planets, rich in dilithium and considered holy ground by the Klingons. :) I am sure CBS would argue that Axanar is principally commercial. ;)

XRays won't penetrate far into the water - as long as you've got water oceans, you can have underwater life. Of course if you have that, then you probably have an atmosphere above it.

Good point. There might be a problem retaining the atmosphere, though. But we'll soon (my guess: before SpaceX lands humans on Mars!) learn much more about these atmospheres!

The system is only about 500 Ma old, so biogenic O2-rich atmospheres/ozone layers seem not very likely anyway.

Offline high road

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Arxiv preprint on UV / XUV and habitability in the Trappist-1 system. Long story short, if there is an Earth-like moderately dense atmosphere with an ozone layer - all good. That failing, not even UV-resistant bacteria can make it.

https://arxiv.org/abs/1702.06936

And here I was thinking life predated the ozone layer by 1.5 billion years.

Offline the_roche_lobe

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Quote
The system is only about 500 Ma old, so biogenic O2-rich atmospheres/ozone layers seem not very likely anyway.

That number is only a very rough minimum. The age of extremely long lived M dwarfs is notoriously hard to pin down because they evolve so slowly. The star could be billions of years old, especially because it seems to be a quiet star flare-wise.

P

Offline Ben the Space Brit

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I was thinking about the inverse square law the other night. Would closer orbits necessarily mean far greater proportional exposures to high-frequency photons? So, irrespective of their relative output levels, M-type dwarves thermal habitability zones would be automatically more likely to be far more hazardous in terms of ionising radiation?
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Offline jebbo

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That number is only a very rough minimum. The age of extremely long lived M dwarfs is notoriously hard to pin down because they evolve so slowly. The star could be billions of years old, especially because it seems to be a quiet star flare-wise.

On the other hand, it has a high metallicity ([Fe/H] = +0.04), which suggests it can't be *too* old. Similarly, it has a fast rotation rate. But as you say, 0.5 billion is a minimum. It could easily be a few billion.

--- Tony
 
« Last Edit: 02/23/2017 04:16 PM by jebbo »

Offline CuddlyRocket

That number is only a very rough minimum. The age of extremely long lived M dwarfs is notoriously hard to pin down because they evolve so slowly. The star could be billions of years old, especially because it seems to be a quiet star flare-wise.

On the other hand, it has a high metallicity ([Fe/H] = +0.04), which suggests it can be *too* old. Similarly, it has a fast rotation rate. But as you say, 0.5 billion is a minimum. It could easily be a few billion.

What is needed is radiometric dating of the rocks of the planets and other objects in this stellar system - though this is a touch beyond our current technology! :)

Offline sghill

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I was thinking to myself that this solar system model may be giving us a glimpse of what planetary systems look like in the absence of a gas giant that cleans smaller rocky bodies out of the inner orbital space.


Yes, I think the runaway greenhouse limit for the smallest red dwarfs is around 0.9 S_Earth. So if scaled properly, the HZ is slightly further out for a smaller star. The paper preprint linked above says that they did climate models on all of them, and b, c, d ran into the runaway greenhouse state, while e, f, g remained temperate (h is likely too cold).


"H" is for Hoth. :)

« Last Edit: 02/23/2017 05:38 PM by sghill »
Bring the thunder Elon!

Offline Star One

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By the way there's a special Google Doodle today celebrating this discovery.

IAU really need to give this star a proper name.
« Last Edit: 02/23/2017 01:28 PM by Star One »

Offline Machdiamond

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Great job on the public outreach, it has been a big hit on mainstream media around the world (front page of my newspaper this morning).
It has its own website: http://www.trappist.one/

Offline jebbo

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I was thinking to myself that this solar system model may be giving us a glimpse of what planetary systems look like in the absence of a gas giant that cleans smaller rocky bodies out of the inner orbital space.

The speckle imaging rules out anything from 0.32 AU to about 14 AU, so I was thinking more that this is maximal use of the initial disc ... to me it feels much more a scaled up Jovian system than a scaled down Solar System, and I'm thinking of "b" as an Io analogue.

There is just so much still to learn. Very exciting times!!!

Oh, and typo fixed :-) and on metallicity, I want to see a more detailed breakdown ... in particular, Li.

--- Tony

Offline Star One

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Here's an interesting post from Centauri Dreams.

Quote
Greg Laughlin is always worth reading. Here’s the relevant paragraph from his post today:

“2MASS J20362926-0502285, now much better known as TRAPPIST-1, straddles the boundary between the lowest mass main sequence stars and the highest mass brown dwarfs. Depending on precisely what its mass and metallicity turn out to be, it could either be arriving at self-sustaining core hydrogen fusion, which would make it a main sequence star (about a 60% chance) or it could be currently achieving its peak brown dwarf luminosity and bracing for a near-eternity of cooling into obscurity (about a 40% chance).”

Also quite interesting here is his take on the future of this system, assuming TRAPPIST-1 is indeed a main sequence star:

“An object with solar composition and 0.08 solar masses never turns into a red giant. As time goes on, it maintains a near-constant radius, and slowly burns nearly all of its hydrogen into helium. In roughly 10 trillion years, TRAPPIST-1 will reach a maximum temperature of ~4000K, pushing it briefly toward K-dwarf status for a few tens of billions of years, before eventually running out of fuel and fading out as a degenerate helium dwarf.”

http://www.centauri-dreams.org/?p=37204

Offline JasonAW3

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An interesting thought has occurred to me.

      With M class dwarf stars, it's pretty much assumed that planets in the habitable zone would likely be tidally locked.  (I suspect that this also assumes no large mass satellite companion)  As was mentioned in the press briefing, these planets are close enough in their orbits that they tend to tug on each other as they pass on another.

      I would think, with this interaction, that, if each world has an initial rotation, that the tidal forces acting on each planet, would tend to maintain a certain amount of rotation of each planet, while still providing tides to what ever atmosphere and/or surface liquids, that might exist on those planets.

      My reasoning is based largely upon the current Earth/Luna tidal interaction that has slowed Earth's rotation from 10 hour days initially, to 24 hour days over 4.5 billion years.  In this case, rather than slow down the rotation of each planet, the various planets interacting with each other would help maintain a more or less average rotation rate for each, based upon each orbital position and each planet's interaction with the others.

      This would also imply a certain level of tidal heating of each planet's core, which could, in theory, help to produce magnetic fields for each planet, depending on the metallic content of each planet's core.

      Of course, I could be wrong, but this does make a certain amount of sense to me.
My God!  It's full of universes!

Offline Star One

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What impact could larger planets such as gas and ice giants further out in the system have on the habitability of these rocky worlds?
« Last Edit: 02/23/2017 06:41 PM by Star One »

Offline Hungry4info3

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An interesting thought has occurred to me. ...

That's not quite how it works. The star is, by far, the dominant tidal influence on the planet's rotation states.
Test your idea though: The mass ratio of TRAPPIST-1 to its planets is about the same as that of Jupiter to its moons, Saturn to its moons, and Uranus to its moons, with rather similar levels of compactness (Jupiter being somewhat less of course).

What are the rotation states are the moons of Jupiter, Saturn, and Uranus?

(Also, I suspect the torque on a planet's rotation by a passing planet would probably average to zero, given circular orbits)
« Last Edit: 02/23/2017 09:02 PM by Hungry4info3 »

Offline JasonAW3

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An interesting thought has occurred to me. ...

That's not quite how it works. The star is, by far, the dominant tidal influence on the planet's rotation states.
Test your idea though: The mass ratio of TRAPPIST-1 to its planets is about the same as that of Jupiter to its moons, Saturn to its moons, and Uranus to its moons, with rather similar levels of compactness (Jupiter being somewhat less of course).

What are the rotation states are the moons of Jupiter, Saturn, and Uranus?

(Also, I suspect the torque on a planet's rotation by a passing planet would probably average to zero, given circular orbits)

From what was said at the news conference, it seems that these planets have enough of an influence on each other tospeedupand slow down each other's orbits.  Fortunately, the resonance of the orbits seem to keep the whole system stable.

But I'd still like it if someone could run the numbers.  Most likely you're correct, but this doesn't exclude the possibility that some of those planets might have moons of a similar size ratio as the Earth and moon.  (I think it's exceedingly unlikely, given the push and pull that these planets seem to have with one another, but still, possible I suppose).
My God!  It's full of universes!

Offline Hungry4info3

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So the problem with massive moons around tidally locked planets is that the Hill sphere radius will always be much, much smaller than the synchronous orbit radius. Therefore *all* moons will orbit the planet faster than the planet rotates. The tides will bring the two objects together, pretty quickly if the moon is reasonably massive.

Large moons cannot exist around any of the detected TRAPPIST-1 planets, even before you consider planet-planet interactions.
« Last Edit: 02/24/2017 02:14 AM by Hungry4info3 »

Offline Archibald

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By the way there's a special Google Doodle today celebrating this discovery.

IAU really need to give this star a proper name.

https://en.wikipedia.org/wiki/Trappists

Offline jebbo

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A paper on the Hubble observations of Trappist-1:

Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-α line
https://arxiv.org/abs/1702.07004

Key quote from the conclusions:
Quote
[W]ater vapor in the upper atmosphere could photo-dissociate and sustain an outflow of escaping hydrogen. The stellar Ly-α line is bright enough to perform transit spectroscopy, and we detect marginal flux decreases in localized, high-velocity ranges during the transit of planet b, and shortly after the
transit of planet c. This could hint at the presence of extended hydrogen exospheres around the two inner planets, and suggest that atmospheric escape might play an active role in the evolution of all TRAPPIST-1 planets.

--- Tony
« Last Edit: 02/24/2017 08:30 AM by jebbo »

Offline sghill

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What impact could larger planets such as gas and ice giants further out in the system have on the habitability of these rocky worlds?

They can help clear out devastating comets, asteroids, dwarf, and proto-planets from impacting the inner planets.

Personally, I think the shear volume of inner planets in resonant orbits indicates there are no gas giants in that system (see my previous post) unless they are verrrry far out. It (they) would have swept some of those inner worlds clear.



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Offline as58

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The discovery paper (supplement) discusses the long-term stability of the system and it is mentioned that it's very hard to keep even the known system stable.

Offline gosnold

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The discovery paper (supplement) discusses the long-term stability of the system and it is mentioned that it's very hard to keep even the known system stable.

Isn't that true even for our solar system? I recall reading the accuracy of our orbital predication degrades past a couple hundred million years.

Offline as58

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The discovery paper (supplement) discusses the long-term stability of the system and it is mentioned that it's very hard to keep even the known system stable.

Isn't that true even for our solar system? I recall reading the accuracy of our orbital predication degrades past a couple hundred million years.

Sure, to some extent. But in case of TRAPPIST-1 most simulations apparently lead to disruption of the system on a time scale of a million years or less.

Offline Star One

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The discovery paper (supplement) discusses the long-term stability of the system and it is mentioned that it's very hard to keep even the known system stable.

Isn't that true even for our solar system? I recall reading the accuracy of our orbital predication degrades past a couple hundred million years.

Sure, to some extent. But in case of TRAPPIST-1 most simulations apparently lead to disruption of the system on a time scale of a million years or less.

That's not quite correct as if you use a different statistical method you get a differing more positive result and either way there's a great deal of uncertainty in all methods used.

http://astronomy.stackexchange.com/questions/20160/are-the-trappist-1-planets-in-stable-orbits

As it says here and I've read elsewhere the planets fall into near-integer resonances.
« Last Edit: 02/24/2017 06:58 PM by Star One »

Offline Star One

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Quote
Judy Schmidt‏ @SpaceGeck

I've got an accurate little TRAPPIST-1 system set up in Blender. This is 1 year of looking at the star from planet e.

Animation on link below.

https://mobile.twitter.com/SpaceGeck/status/835552362534219777

Offline Star One

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A Nearby Galactic Empire?

Quote
Meanwhile, we can do at least one experiment: Examine this system for radio signals that would indicate the presence of intelligence.  And indeed, the SETI Institute used its Allen Telescope Array last year to observe the environs of Trappist 1, scanning through ten billion radio channels in search of signals.  No transmissions were detected, although new observations are in the offing. 

How sensitive was this search?  Assuming that the putative inhabitants of this solar system can use a transmitting antenna as large as the 500 meter FAST radio telescope in China to beam their messages our way, then the Allen Array could have found a signal if the aliens use a transmitter with 100 kilowatts of power or more.  This is only about ten times as energetic as the radar down at your local airport.

And whether or not Trappist 1 has inhabitants, its discovery has underlined the growing conviction that the universe is replete with real estate on which biology could both arise and flourish.  If you still think the rest of the universe is sterile, you are surely singular, and probably wrong.

http://www.seti.org/seti-institute/Nearby-Galactic-Empire

The (Potentially) Habitable Worlds of TRAPPIST-1

Quote
When the news about the seven planets of TRAPPIST-1 broke, I immediately wondered what Andrew LePage’s take on habitability would be. A physicist and writer with numerous online essays and a host of articles in magazines like Scientific American and Sky & Telescope, LePage is also a specialist in the processing and analysis of remote sensing data. He has put this background in data analytics to frequent use in his highly regarded ‘habitable planet reality checks,’ which can be found on his Drew ex Machina site. Having run a thorough analysis of the TRAPPIST-1 situation the other day, Drew now gives us the gist of his findings, which move at least several of the TRAPPIST-1 planets into a potentially interesting category indeed.

http://www.centauri-dreams.org/?p=37225
« Last Edit: 02/27/2017 07:14 PM by Star One »

Offline Star One

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Offline Star One

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Public tries to name 7 new planets after Nasa discovery- with chaotic results

http://www.telegraph.co.uk/news/2017/03/02/nasa-asks-public-help-name-7-new-plants-chaotic-results/

Offline CuddlyRocket

Public tries to name 7 new planets after Nasa discovery- with chaotic results

http://www.telegraph.co.uk/news/2017/03/02/nasa-asks-public-help-name-7-new-plants-chaotic-results/

One of the reasons the IAU was founded was to stop this kind of chaos when it comes to the naming of celestial bodies (the arguments over the naming of Neptune were quite vicious). But in order to prevent other people giving exoplanets names, the IAU has to get round to naming them itself! I know Eric Mamajek, who is a member of the Executive Committee Working Group on the Public Naming of Planets and Planetary Satellites, is keen that the IAU runs another round of its successful NameExoWorlds process, though apparently there's opposition (professional astronomers can get a bit snobby at times IMO).

Offline Star One

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Public tries to name 7 new planets after Nasa discovery- with chaotic results

http://www.telegraph.co.uk/news/2017/03/02/nasa-asks-public-help-name-7-new-plants-chaotic-results/

One of the reasons the IAU was founded was to stop this kind of chaos when it comes to the naming of celestial bodies (the arguments over the naming of Neptune were quite vicious). But in order to prevent other people giving exoplanets names, the IAU has to get round to naming them itself! I know Eric Mamajek, who is a member of the Executive Committee Working Group on the Public Naming of Planets and Planetary Satellites, is keen that the IAU runs another round of its successful NameExoWorlds process, though apparently there's opposition (professional astronomers can get a bit snobby at times IMO).

NASA I suppose could have pointed out it was actually up to the IAU to name them, but then that would have taken all the fun out of it.

Offline jebbo

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The raw K2 light curve will be available for download from MAST at 9am PST on Tuesday.

Edit: details here http://archive.stsci.edu/k2/trappist1/index.html

-- Tony
« Last Edit: 03/04/2017 07:58 PM by jebbo »

Offline jebbo

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The K2 light curve is available and, as expect, it seems the period of "h" has been pinned down. The linked tweet shows the folded long cadence data:

https://twitter.com/AgolEric/status/839549713313476608

They are being coy over the period though ...

Also, Trappist-1 flares frequently:

https://github.com/jradavenport/trappist/blob/master/explore.ipynb
https://twitter.com/johngizis/status/839721186133180417

I expect the next few days will see better analysis and things like TTV O-C plots.

--- Tony
« Last Edit: 03/09/2017 10:25 AM by jebbo »

Offline Star One

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NASA gives out data about star with 7 Earth-sized planets for free

http://mashable.com/2017/03/08/trappist-1-data-nasa-kepler-space-telescope/

Think it's a bit sad when it sounds a bit surprising to people that scientific data should actually be distributed freely.

This is worth a look on as well.

https://www.reddit.com/r/space/comments/5yanmj/oc_nasa_just_released_keplers_data_on_trappist1/
« Last Edit: 03/09/2017 09:52 AM by Star One »

Offline as58

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A period of ~23 days for TRAPPIST-1h has been mentioned, which puts is close to the middle of the error bars announced earlier.

The star does seem to flare a lot.

Offline jebbo

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Yes, my tools suggest about ~23.4 but I'm hesitant as I lost my old KepCurve source code and the current re-write is very primitive still (to say the least!).

FWIW, my data was backed up perfectly; turns out my source only had 1 backup and the backup copy managed to copy a totally corrupt archive.  Needless to say, this time, I'm paying more attention :-) [ and will put the source on github when more useable ]

Edit: thinking about it, 23.4 is not favoured but I have 3 periods to check :-)

--- Tony
« Last Edit: 03/09/2017 02:25 PM by jebbo »

Offline jebbo

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A new Trappist-1 paper will be on arxiv.org tomorrow, with details of "h" and I suspect updated periods for the other planets.

It may also include a corrected stellar rotation period (a paper last year in Nature has this as ~1.4 days; however it is clear from the raw light curve that is it ~3.27d).

https://twitter.com/ethan_kruse/status/841092095448305665

--- Tony

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #116 on: 03/13/2017 03:17 PM »
Seems it's proving a little tricky trying to figure out how old TRAPPIST-1 is.

http://www.sciencealert.com/astronomers-question-if-trappist-1-s-planets-are-habitable-afterall

Offline Ben the Space Brit

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #117 on: 03/13/2017 03:39 PM »
That's class-M dwarves for you: Once they hit main sequence, there's really no way to easily tell the difference between 100 million or 10 billion years old!
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Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #118 on: 03/13/2017 03:53 PM »
That's class-M dwarves for you: Once they hit main sequence, there's really no way to easily tell the difference between 100 million or 10 billion years old!

From my limited understanding of that article it's the radiation output that's proving contradictory ageing wise.

Offline jebbo

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #119 on: 03/13/2017 04:27 PM »
That's class-M dwarves for you: Once they hit main sequence, there's really no way to easily tell the difference between 100 million or 10 billion years old!

From my limited understanding of that article it's the radiation output that's proving contradictory ageing wise.

It's worse than that. I think that article references the 1.4 day stellar rotation period from Nature. But the actual rotation period is more like 3.3 days.

So that is contradictory as well, indicating a much older star (>= ~1bn). However,  gyrochronology is poorly constrained for M dwarfs.

--- Tony

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #120 on: 03/13/2017 04:28 PM »
That's class-M dwarves for you: Once they hit main sequence, there's really no way to easily tell the difference between 100 million or 10 billion years old!

From my limited understanding of that article it's the radiation output that's proving contradictory ageing wise.

It's worse than that. I think that article references the 1.4 day stellar rotation period from Nature. But the actual rotation period is more like 3.3 days.

So that is contradictory as well, indicating a much older star (>= ~1bn). However,  gyrochronology is poorly constrained for M dwarfs.

--- Tony

Don't stars slow down as that get older or does that only apply to ones like our Sun?

Offline Ben the Space Brit

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #121 on: 03/13/2017 04:39 PM »
If I understand correctly, the problem is that the different indicators are giving different age ranges for TRAPPIST-1. This would indicate either the existing theoretical models are wrong or (and this is probably more likely) TRAPPIST-1 is an anomalous body and we can't take anything about it for granted based on analysis of other M8s.
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Offline jebbo

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #122 on: 03/13/2017 04:41 PM »
Don't stars slow down as that get older or does that only apply to ones like our Sun?

Yes, but the rotation/age relationship is not that well understood for M dwarfs. However, ~2km/s v sin i is very low even for old M dwarfs.

--- Tony

Offline Star One

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NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #123 on: 03/13/2017 04:46 PM »
If I understand correctly, the problem is that the different indicators are giving different age ranges for TRAPPIST-1. This would indicate either the existing theoretical models are wrong or (and this is probably more likely) TRAPPIST-1 is an anomalous body and we can't take anything about it for granted based on analysis of other M8s.

Could it be because it's just on the line to being a brown dwarf. Perhaps and I don't know if this is a possibility that it started off as a brown dwarf but somehow crossed the boundary into being a red dwarf at a later point?
« Last Edit: 03/13/2017 04:49 PM by Star One »

Offline as58

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #124 on: 03/13/2017 04:48 PM »
In general slow rotation indicates old age, but there's quite a bit of spread. Determining the age of main-sequence stars is very difficult.

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #125 on: 03/13/2017 08:11 PM »
Discovery of seven-exoplanet system energizes world science news

TRAPPIST-1 boosts excitement among those who wonder: Is there life out there somewhere?

http://physicstoday.scitation.org/do/10.1063/PT.5.8208/full/

Offline CuddlyRocket

Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #126 on: 03/13/2017 08:47 PM »
If I understand correctly, the problem is that the different indicators are giving different age ranges for TRAPPIST-1. This would indicate either the existing theoretical models are wrong or (and this is probably more likely) TRAPPIST-1 is an anomalous body and we can't take anything about it for granted based on analysis of other M8s.

Could it be because it's just on the line to being a brown dwarf.

My understanding is that although astronomers think it is a very low-mass star rather than a brown dwarf, this is by no means certain and it could actually be a brown dwarf. It's very difficult to distinguish between a very low-mass star and a young brown dwarf.

Quote
Perhaps and I don't know if this is a possibility that it started off as a brown dwarf but somehow crossed the boundary into being a red dwarf at a later point?

It would've had to have absorbed sufficient additional mass at some point after formation - preferably hydrogen, but most kinds of mass would do (how much mass would depend on how close the brown dwarf was to being a red dwarf!). One possibility is that a hot Jupiter spiraled in too close and crashed into the brown dwarf, the current exoplanets forming after this event.

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #127 on: 03/13/2017 08:54 PM »
If I understand correctly, the problem is that the different indicators are giving different age ranges for TRAPPIST-1. This would indicate either the existing theoretical models are wrong or (and this is probably more likely) TRAPPIST-1 is an anomalous body and we can't take anything about it for granted based on analysis of other M8s.

Could it be because it's just on the line to being a brown dwarf.

My understanding is that although astronomers think it is a very low-mass star rather than a brown dwarf, this is by no means certain and it could actually be a brown dwarf. It's very difficult to distinguish between a very low-mass star and a young brown dwarf.

Quote
Perhaps and I don't know if this is a possibility that it started off as a brown dwarf but somehow crossed the boundary into being a red dwarf at a later point?

It would've had to have absorbed sufficient additional mass at some point after formation - preferably hydrogen, but most kinds of mass would do (how much mass would depend on how close the brown dwarf was to being a red dwarf!). One possibility is that a hot Jupiter spiraled in too close and crashed into the brown dwarf, the current exoplanets forming after this event.

It does seem to be an odd star even by the standards of M dwarfs. It's smaller than Proxima Centauri I believe, which seems more like a 'typical' M dwarf if there's such a thing.

Offline Star One

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NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #128 on: 03/14/2017 08:36 AM »
New paper refining the orbit of h that actually sits at the snow line of TRAPPIST-1. Also refining the rotational period of the star and age. Also according to the relevant tweets the system of planets appears to be stable.

Quote
The TRAPPIST-1 system is the first transiting planet system found orbiting an ultra-cool dwarf star. At least seven planets similar to Earth in radius and in mass were previously found to transit this host star. Subsequently, TRAPPIST-1 was observed as part of the K2 mission and, with these new data, we report the measurement of an 18.764 d orbital period for the outermost planet, TRAPPIST-1h, which was unconstrained until now. This value matches our theoretical expectations based on Laplace relations and places TRAPPIST-1h as the seventh member of a complex chain, with three-body resonances linking every member. We find that TRAPPIST-1h has a radius of 0.715 Earth radii and an equilibrium temperature of 169 K, placing it at the snow line. We have also measured the rotational period of the star at 3.3 d and detected a number of flares consistent with an active, middle-aged, late M dwarf.

https://arxiv.org/abs/1703.04166
« Last Edit: 03/14/2017 08:40 AM by Star One »

Offline clongton

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #129 on: 03/14/2017 04:01 PM »
We have also measured the rotational period of the star at 3.3 d and detected a number of flares consistent with an active, middle-aged, late M dwarf.

So how old is an active, middle-aged, late M dwarf?
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I started my career on the Saturn-V F-1A engine

Offline as58

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #130 on: 03/14/2017 05:01 PM »
We have also measured the rotational period of the star at 3.3 d and detected a number of flares consistent with an active, middle-aged, late M dwarf.

So how old is an active, middle-aged, late M dwarf?

Quote
While the long spin-down times of ultra-cool dwarfs prevent derivation of a robust gyrochronology relation, the rotational
period of TRAPPIST-1 is roughly in the middle of the period distribution of nearby late M dwarfs, suggesting an age in the range
3−8 Gyr based on a star formation history that declines slightly with time.

Offline clongton

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #131 on: 03/14/2017 08:31 PM »
... suggesting an age in the range 3−8 Gyr based on a star formation history that declines slightly with time.

Assuming Gyr means Gigayear, or 1 billion years, then the Trappist star is 3-8 billion years old, which is the same "range" as Sol, which is 4.55 billion years old. Do I have that right?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #132 on: 03/14/2017 08:50 PM »
... suggesting an age in the range 3−8 Gyr based on a star formation history that declines slightly with time.

Assuming Gyr means Gigayear, or 1 billion years, then the Trappist star is 3-8 billion years old, which is the same "range" as Sol, which is 4.55 billion years old. Do I have that right?

Yes.

I sometimes wonder how many of the stars in the locality came out of the same stellar nursery as our sun.

Offline Star One

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NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #133 on: 03/26/2017 02:15 PM »
7 Alien 'Earths' May Be Swapping Life via Meteorites

Quote
Now, Lingam and Loeb have calculated that exact probability. Comparing the TRAPPIST-1 planets to Earth and Mars, they found that the travel time between one planet and the next is shorter by a factor of a hundred. This boosts the chance that life can survive such a harrowing journey. They also found that the likelihood of one planet’s debris landing on another is larger by a factor of 20 or so.

Altogether, the possibility that life can play hopscotch from one planet to the next is a few thousand times higher among the TRAPPIST-1 worlds than the possibility that it did the same from Mars to Earth.

http://news.nationalgeographic.com/2017/03/earth-planets-aliens-life-panspermia-space-science/
« Last Edit: 03/26/2017 02:20 PM by Star One »

Offline jebbo

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #134 on: 03/27/2017 03:26 PM »
I sometimes wonder how many of the stars in the locality came out of the same stellar nursery as our sun.

It's a good question: there are several searches looking for "solar twins" ... from memory,  we've found a few candidates but not many.

But Trappist-1 is not one of them ... its relative velocity is too high for it to be a close neighbour for long. Again from memory, its velocity puts it on the YD/OD boundary.

--- Tony

Offline clongton

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #135 on: 03/27/2017 10:33 PM »
I sometimes wonder how many of the stars in the locality came out of the same stellar nursery as our sun.

It's a good question: there are several searches looking for "solar twins" ... from memory,  we've found a few candidates but not many.

But Trappist-1 is not one of them ... its relative velocity is too high for it to be a close neighbour for long. Again from memory, its velocity puts it on the YD/OD boundary.

--- Tony


Forgive my ignorance Tony but what is the YD/OD boundary?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #136 on: 03/27/2017 10:51 PM »
I sometimes wonder how many of the stars in the locality came out of the same stellar nursery as our sun.

It's a good question: there are several searches looking for "solar twins" ... from memory,  we've found a few candidates but not many.

But Trappist-1 is not one of them ... its relative velocity is too high for it to be a close neighbour for long. Again from memory, its velocity puts it on the YD/OD boundary.

--- Tony


Forgive my ignorance Tony but what is the YD/OD boundary?

I was wondering that as well TBH.

Offline as58

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #137 on: 03/28/2017 08:01 AM »
I sometimes wonder how many of the stars in the locality came out of the same stellar nursery as our sun.

It's a good question: there are several searches looking for "solar twins" ... from memory,  we've found a few candidates but not many.

But Trappist-1 is not one of them ... its relative velocity is too high for it to be a close neighbour for long. Again from memory, its velocity puts it on the YD/OD boundary.

--- Tony


Forgive my ignorance Tony but what is the YD/OD boundary?

I was wondering that as well TBH.

young disk/old disk? Though they're more commonly called thin and thick disks.

Offline jebbo

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #138 on: 03/28/2017 08:04 AM »
young disk/old disk? Though they're more commonly called thin and thick disks.

Yes, young disk/old disk ... I was following the terminology from recent HARPS papers (who seem to favour young / old over thin / thick)

E.g. https://arxiv.org/abs/1703.05386

--- Tony

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #139 on: 03/30/2017 06:46 PM »
Frequent flaring in the TRAPPIST-1 system - unsuited for life?

Quote
We analyze short cadence K2 light curve of the TRAPPIST-1 system. Fourier analysis of the data suggests Prot=3.295±0.003 days. The light curve shows several flares, of which we analyzed 42 events, these have integrated flare energies of  1.26×1030−1.24×1033  ergs. Approximately 12% of the flares were complex, multi-peaked eruptions. The flaring and the possible rotational modulation shows no obvious correlation. The flaring activity of TRAPPIST-1 probably continuously alters the atmospheres of the orbiting exoplanets, making these less favorable for hosting life.

https://arxiv.org/abs/1703.10130

Offline Mongo62

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #140 on: 04/03/2017 01:37 AM »
A revolution is brewing: observations of TRAPPIST-1 exoplanetary system fosters a new biomarker

Quote
The recent discovery of seven potentially habitable Earth-size planets around the ultra-cool star TRAPPIST-1 has further fueled the hunt for extraterrestrial life. Current methods focus on closely monitoring the host star to look for biomarkers in the transmission signature of exoplanet's atmosphere. However, the outcome of these methods remain uncertain and difficult to disentangle with abiotic alternatives. Recent exoplanet direct imaging observations by THIRSTY, an ultra-high contrast coronagraph located in La Trappe (France), lead us to propose a universal and unambiguous habitability criterion which we directly demonstrate for the TRAPPIST-1 system. Within this new framework, we find that TRAPPIST-1g possesses the first unambiguously habitable environment in our galaxy, with a liquid water percentage that could be as large as ∼ 90 %. Our calculations hinge on a new set of biomarkers, CO2 and CxH2(x+1)O (liquid and gaseous), that could cover up to ∼ 10 % of the planetary surface and atmosphere. THIRSTY and TRAPPIST recent observations accompanied by our new, unbiased habitability criterion may quench our thirst for the search for extraterrestrial life. However, the search for intelligence must continue within and beyond our Solar System.

I was going to edit my original post to point out that it was an April Fool's joke by the author, but accidentally hit "delete" instead, so I am reposting.
« Last Edit: 04/03/2017 01:38 AM by Mongo62 »

Offline CuddlyRocket

Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #141 on: 04/17/2017 07:58 AM »
Updated Masses for the TRAPPIST-1 Planets (arXiv)

Quote
The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date. The short baseline of the available discovery observations, however, means that the planetary masses (obtained through measurement of transit timing variations of the planets of the system) are not yet well constrained. The masses reported in the discovery paper were derived using a combination of photometric timing measurements obtained from the ground and from the Spitzer spacecraft, and have uncertainties ranging from 30\% to nearly 100\%, with the mass of the outermost, P=18.8d, planet h remaining unmeasured. Here, we present an analysis that supplements the timing measurements of the discovery paper with 73.6 days of photometry obtained by the K2 Mission. Our analysis refines the orbital parameters for all of the planets in the system. We substantially improve the upper bounds on eccentricity for inner six planets (finding e<0.02 for inner six known members of the system), and we derive masses of 0.79±0.27M⊕, 1.63±0.63M⊕, 0.33±0.15M⊕, 0.24+0.56−0.24M⊕, 0.36±0.12M⊕, 0.566±0.038M⊕, and 0.086±0.084M⊕ for planets b, c, d, e, f, g, and h, respectively.

Quote
Figure 4 indicates that – to within the errors of our determinations – the four most distant planets are consistent with pure water compositions, and in any event, are substantially less dense either Mars or Venus.

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #142 on: 04/25/2017 05:55 PM »
Further Work on TRAPPIST-1

http://www.centauri-dreams.org/?p=37557

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #143 on: 05/11/2017 09:24 AM »
Exoplanet Puzzle Cracked by Jazz Musicians

Quote
There’s more than one way to appreciate the results. While Tamayo was working on his simulations, he was approached by Matt Russo, a fellow postdoc and jazz guitarist who thought the TRAPPIST-1 resonances looked familiar from music theory. Now, coordinated with the release of Tamayo’s paper, Russo, Tamayo and the musician Andrew Santaguida have teamed up to translate the system’s intricate arrangement of passing worlds into a musical composition.

The seventh planet, h, orbits about once every three weeks. Sped up some 200 million times and expressed in sound waves, that frequency is a C note. From there, the known ratios between planets determine every other planet’s signature note. Together the notes form a major ninth chord. “It’s really remarkable that it worked out like that,” Russo said. “Even with a different pattern of resonances, you wouldn’t get a chord that sounds as good.”

On top of that, the team added drumbeats for whenever an inner planet overtakes an outer neighbor — moments that correspond to close gravitational interactions among the planets. Compared to human percussion, Russo said, “It’s a super-creative drummer. It’s doing something that nobody else would think of.”

https://www.quantamagazine.org/exoplanet-puzzle-cracked-by-jazz-musicians/

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #144 on: 05/17/2017 09:31 AM »
Worlds without Moons: Exomoon Constraints for Compact Planetary Systems

Quote
One of the primary surprises of exoplanet detections has been the discovery of compact planetary systems, whereby numerous planets reside within ~0.5 au of the host star. Many of these kinds of systems have been discovered in recent years, indicating that they are a fairly common orbital architecture. Of particular interest are those systems for which the host star is low mass, thus potentially enabling one or more of the planets to lie within the habitable zone of the host star. One of the contributors to the habitability of the Earth is the presence of a substantial moon whose tidal effects can stabilize axial tilt variations and increase the rate of tidal pool formation. Here, we explore the constraints on the presence of moons for planets in compact systems based on Hill radii and Roche limit considerations. We apply these constraints to the TRAPPIST-1 system and demonstrate that most of the planets are very likely to be worlds without moons.

http://iopscience.iop.org/article/10.3847/2041-8213/aa6bf2/meta;jsessionid=A3DBDC5F5F51BE049C8E8088EB9EAE2D.c1.iopscience.cld.iop.org

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #145 on: 05/18/2017 07:32 PM »
Atmosphere discovery makes Trappist-1 exoplanet priority in hunt for alien life

Quote
With Nasa’s James Webb Space Telescope not due to launch until late 2018, the scientists turned to computer models to find out whether the Trappist-1 planets could have long-lived atmospheres. From details of the Trappist-1 system, which lies 39 light years distant, they worked out the intensity of the stellar wind – the rush of high energy particles streaming out of the star – and the effect it would have on the seven orbiting planets.

Quote
The intensity of the solar wind destroyed the atmospheres of the inner Trappist-1 planets within millions of years. But planets further out fared better, their atmospheres surviving for billions of years, the models found. According to the scientists, while the seventh planet around the star is considered too cold for liquid water to exist on the surface, the sixth planet, Trappist-1g, appears to be the most likely home for life in the Trappist-1 system.

https://www.theguardian.com/science/2017/may/18/atmosphere-discovery-makes-trappist-1-exoplanet-priority-in-hunt-for-alien-life

Here's the paper the article is based on.

https://arxiv.org/abs/1705.05535v1

Offline clongton

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #146 on: 05/19/2017 12:47 AM »
Exoplanet Puzzle Cracked by Jazz Musicians

Quote
There’s more than one way to appreciate the results. While Tamayo was working on his simulations, he was approached by Matt Russo, a fellow postdoc and jazz guitarist who thought the TRAPPIST-1 resonances looked familiar from music theory. Now, coordinated with the release of Tamayo’s paper, Russo, Tamayo and the musician Andrew Santaguida have teamed up to translate the system’s intricate arrangement of passing worlds into a musical composition.

The seventh planet, h, orbits about once every three weeks. Sped up some 200 million times and expressed in sound waves, that frequency is a C note. From there, the known ratios between planets determine every other planet’s signature note. Together the notes form a major ninth chord. “It’s really remarkable that it worked out like that,” Russo said. “Even with a different pattern of resonances, you wouldn’t get a chord that sounds as good.”

On top of that, the team added drumbeats for whenever an inner planet overtakes an outer neighbor — moments that correspond to close gravitational interactions among the planets. Compared to human percussion, Russo said, “It’s a super-creative drummer. It’s doing something that nobody else would think of.”

https://www.quantamagazine.org/exoplanet-puzzle-cracked-by-jazz-musicians/

Brings new meaning to the phrase "Music of the Spheres". Perhaps the ancients were right after all?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #147 on: 05/22/2017 08:58 PM »
Kepler telescope spies details of TRAPPIST-1 system's outermost planet

https://www.eurekalert.org/pub_releases/2017-05/uow-kt052217.php

Offline Alpha_Centauri

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #148 on: 05/24/2017 06:35 PM »
Why are you posting stuff by a nutjob with a penchant for caps as if it means anything?
« Last Edit: 05/24/2017 06:38 PM by Alpha_Centauri »

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #149 on: 05/24/2017 07:02 PM »
Why are you posting stuff by a nutjob with a penchant for caps as if it means anything?

Well his idea was getting consideration over there & I regard that as a decent site for your information.

By the way would you kindly show some consideration to those with mental health issues in general rather than throwing around comments like 'nutjob' as it makes you sound like a ten year old.

Online FutureSpaceTourist

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #150 on: 08/12/2017 11:13 PM »
Quote
Aug. 11, 2017
TRAPPIST-1 is Older Than Our Solar System

If we want to know more about whether life could survive on a planet outside our solar system, it’s important to know the age of its star. Young stars have frequent releases of high-energy radiation called flares that can zap their planets' surfaces. If the planets are newly formed, their orbits may also be unstable. On the other hand, planets orbiting older stars have survived the spate of youthful flares, but have also been exposed to the ravages of stellar radiation for a longer period of time.

Scientists now have a good estimate for the age of one of the most intriguing planetary systems discovered to date -- TRAPPIST-1, a system of seven Earth-size worlds orbiting an ultra-cool dwarf star about 40 light-years away. Researchers say in a new study that the TRAPPIST-1 star is quite old: between 5.4 and 9.8 billion years. This is up to twice as old as our own solar system, which formed some 4.5 billion years ago.

The seven wonders of TRAPPIST-1 were revealed earlier this year in a NASA news conference, using a combination of results from the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, NASA's Spitzer Space Telescope, and other ground-based telescopes.  Three of the TRAPPIST-1 planets reside in the star’s "habitable zone," the orbital distance where a rocky planet with an atmosphere could have liquid water on its surface. All seven planets are likely tidally locked to their star, each with a perpetual dayside and nightside.

At the time of its discovery, scientists believed the TRAPPIST-1 system had to be at least 500 million years old, since it takes stars of TRAPPIST-1’s low mass (roughly 8 percent that of the Sun) roughly that long to contract to its minimum size, just a bit larger than the planet Jupiter. However, even this lower age limit was uncertain; in theory, the star could be almost as old as the universe itself. Are the orbits of this compact system of planets stable? Might life have enough time to evolve on any of these worlds?

"Our results really help constrain the evolution of the TRAPPIST-1 system, because the system has to have persisted for billions of years. This means the planets had to evolve together, otherwise the system would have fallen apart long ago," said Adam Burgasser, an astronomer at the University of California, San Diego, and the paper's first author. Burgasser teamed up with Eric Mamajek, deputy program scientist for NASA's Exoplanet Exploration Program based at NASA's Jet Propulsion Laboratory, Pasadena, California, to calculate TRAPPIST-1's age. Their results will be published in The Astrophysical Journal.

It is unclear what this older age means for the planets' habitability. On the one hand, older stars flare less than younger stars, and Burgasser and Mamajek confirmed that TRAPPIST-1 is relatively quiet compared to other ultra-cool dwarf stars. On the other hand, since the planets are so close to the star, they have soaked up billions of years of high-energy radiation, which could have boiled off atmospheres and large amounts of water. In fact, the equivalent of an Earth ocean may have evaporated from each TRAPPIST-1 planet except for the two most distant from the host star: planets g and h. In our own solar system, Mars is an example of a planet that likely had liquid water on its surface in the past, but lost most of its water and atmosphere to the Sun’s high-energy radiation over billions of years.

However, old age does not necessarily mean that a planet's atmosphere has been eroded. Given that the TRAPPIST-1 planets have lower densities than Earth, it is possible that large reservoirs of volatile molecules such as water could produce thick atmospheres that would shield the planetary surfaces from harmful radiation. A thick atmosphere could also help redistribute heat to the dark sides of these tidally locked planets, increasing habitable real estate. But this could also backfire in a "runaway greenhouse" process, in which the atmosphere becomes so thick the planet surface overheats – as on Venus.

"If there is life on these planets, I would speculate that it has to be hardy life, because it has to be able to survive some potentially dire scenarios for billions of years," Burgasser said.

Fortunately, low-mass stars like TRAPPIST-1 have temperatures and brightnesses that remain relatively constant over trillions of years, punctuated by occasional magnetic flaring events. The lifetimes of tiny stars like TRAPPIST-1 are predicted to be much, much longer than the 13.7 billion-year age of the universe (the Sun, by comparison, has an expected lifetime of about 10 billion years).

"Stars much more massive than the Sun consume their fuel quickly, brightening over millions of years and exploding as supernovae," Mamajek said. "But TRAPPIST-1 is like a slow-burning candle that will shine for about 900 times longer than the current age of the universe."

Some of the clues Burgasser and Mamajek used to measure the age of TRAPPIST-1 included how fast the star is moving in its orbit around the Milky Way (speedier stars tend to be older), its atmosphere’s chemical composition, and how many flares TRAPPIST-1 had during observational periods. These variables all pointed to a star that is substantially older than our Sun.

Future observations with NASA's Hubble Space Telescope and upcoming James Webb Space Telescope may reveal whether these planets have atmospheres, and whether such atmospheres are like Earth's.

"These new results provide useful context for future observations of the TRAPPIST-1 planets, which could give us great insight into how planetary atmospheres form and evolve, and persist or not," said Tiffany Kataria, exoplanet scientist at JPL, who was not involved in the study.

Future observations with Spitzer could help scientists sharpen their estimates of the TRAPPIST-1 planets’ densities, which would inform their understanding of their compositions.

For more information about TRAPPIST-1, visit:

https://exoplanets.nasa.gov/trappist1

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.

https://www.nasa.gov/feature/jpl/trappist-1-is-older-than-our-solar-system

1st image caption:

Quote
This illustration shows what the TRAPPIST-1 system might look like from a vantage point near planet TRAPPIST-1f (at right).
Credits: NASA/JPL-Caltech

2nd image caption:

Quote
TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its seven planets orbit very close to it.
Credits: NASA/JPL-Caltech

Offline bolun

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #151 on: 09/01/2017 10:41 AM »
HUBBLE DELIVERS FIRST HINTS OF POSSIBLE WATER CONTENT OF TRAPPIST-1 PLANETS [HEIC1713]

31 August 2017

An international team of astronomers used the NASA/ESA Hubble Space Telescope to estimate whether there might be water on the seven earth-sized planets orbiting the nearby dwarf star TRAPPIST-1. The results suggest that the outer planets of the system might still harbour substantial amounts of water. This includes the three planets within the habitable zone of the star, lending further weight to the possibility that they may indeed be habitable.

http://sci.esa.int/hubble/59451-hubble-delivers-first-hints-of-possible-water-content-of-trappist-1-planets-heic1713/

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #152 on: 09/01/2017 10:52 AM »
How on Earth have they managed that when a number of papers have said they will stripped of their atmospheres by their parent star.

Offline Ben the Space Brit

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #153 on: 09/01/2017 11:04 AM »
How on Earth have they managed that when a number of papers have said they will stripped of their atmospheres by their parent star.

The history of astronomy and astrophysics is a history of seemingly-unequivocal paper calculations having to be thrown out of the window because the universe stubbornly refuses to adhere to them. In fairness, any theoretical modelling must necessarily be prone to huge uncertainties due to the difficulty in acquiring sufficient and reliable data to slot into your equations at a distance of nearly 40 l.y.

The lesson? Never fall into the trap of announcing 'definitive' conclusions. Always add the contingency "given the best data currently to hand".
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Offline Star One

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NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #154 on: 09/01/2017 11:48 AM »
How on Earth have they managed that when a number of papers have said they will stripped of their atmospheres by their parent star.

The history of astronomy and astrophysics is a history of seemingly-unequivocal paper calculations having to be thrown out of the window because the universe stubbornly refuses to adhere to them. In fairness, any theoretical modelling must necessarily be prone to huge uncertainties due to the difficulty in acquiring sufficient and reliable data to slot into your equations at a distance of nearly 40 l.y.

The lesson? Never fall into the trap of announcing 'definitive' conclusions. Always add the contingency "given the best data currently to hand".

Very true. Even in our own solar system.

Shame a similar analysis is impossible with Proxima b.

Here's the paper for this announcement.

Temporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets

Quote
The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could harbor liquid water on their surfaces. Ultraviolet observations are essential to measuring their high-energy irradiation and searching for photodissociated water escaping from their putative atmospheres. Our new observations of the TRAPPIST-1 Lyα line during the transit of TRAPPIST-1c show an evolution of the star emission over three months, preventing us from assessing the presence of an extended hydrogen exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape. However, TRAPPIST-1e to h might have lost less than three Earth oceans if hydrodynamic escape stopped once they entered the habitable zone (HZ). We caution that these estimates remain limited by the large uncertainty on the planet masses. They likely represent upper limits on the actual water loss because our assumptions maximize the X-rays to ultraviolet-driven escape, while photodissociation in the upper atmospheres should be the limiting process. Late-stage outgassing could also have contributed significant amounts of water for the outer, more massive planets after they entered the HZ. While our results suggest that the outer planets are the best candidates to search for water with the JWST, they also highlight the need for theoretical studies and complementary observations in all wavelength domains to determine the nature of the TRAPPIST-1 planets and their potential habitability.

http://iopscience.iop.org/article/10.3847/1538-3881/aa859c/meta;jsessionid=D56945E2F9449DE4BE0C8665DA9F46A1.ip-10-40-1-105
« Last Edit: 09/01/2017 11:50 AM by Star One »

Offline Star One

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Re: NASA's Trappist-1 Announcement - Feb 22, 2017
« Reply #155 on: 09/06/2017 06:38 PM »
Could the system have even more planets in this case Gas Giants.

Quote
Boss and colleagues studied the star with astrometric methods, which measure the position of a star in the sky with accuracy great enough to see the slight changes in motion caused by its planets. Astrometry is hard to do, but its rewards are potentially great, as it can provide accurate estimates of a planet’s mass, a value that challenges other planet detection methods. Unlike radial velocity techniques, astrometry works best at planets on long orbital periods, which makes it ideal for trying to locate gas giants like Jupiter in outer system orbits.

The researchers used Carnegie’s CAPSCam astrometric camera, attached to the 2.5-meter du Pont telescope at Las Campanas Observatory (Chile) to determine the upper limits for gas giants at TRAPPIST-1. The result: There are no planets larger than 4.6 times Jupiter’s mass orbiting the star with a period of one year, and no planets larger than 1.6 times Jupiter’s mass orbiting the star with 5 year periods. Given how tightly packed the TRAPPIST-1 planets are, these are wide orbits, and as Boss says, “There is a lot of space for further investigation between the longer-period orbits we studied here and the very short orbits of the seven known TRAPPIST-1 planets.”

https://www.centauri-dreams.org/?p=38424

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