Author Topic: Pale Red Dot  (Read 44221 times)

Offline redliox

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Pale Red Dot
« on: 02/07/2016 09:52 PM »
Between January and April there's an attempt to get spectroscopic readings of the red dwarf Proxima Centauri in an effort to find if it has any planets, Earthlike or otherwise.  Thus far they've established there's no Jovian planets around Proxima, now they seek to verify if there are any Neptunes or Earths around our neighbor.

https://palereddot.org/
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Offline Borklund

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Re: Pale Red Dot
« Reply #1 on: 02/09/2016 01:45 PM »
Very cool. Potentially habitable exoplanets are exciting, and one (or more) at our nearest star would be even more exciting. As far as I could gather from a cursory Google search, the habitable zone around Proxima Centauri is between 0.022 to about 0.054 AU, corresponding to orbital periods from 3.6 to 13.8 days. That works out to between 3.3 million to 8.1 million kilometers, a 4.8 million kilometer band. That's tiny in astronomical terms, as we know them. What would that even look like?

Offline Alpha_Centauri

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Re: Pale Red Dot
« Reply #2 on: 02/09/2016 03:18 PM »
There had been rumours about this for a few weeks and finally as stated in their latest post, https://palereddot.org/the-signal/, the reason this campaign started was because a previous investigation found a (I should stress doubtful) possible planetary signal.  It might be an Earth-mass world and might be around the habitable zone, if it is real at all. 

Offline Bubbinski

Re: Pale Red Dot
« Reply #3 on: 02/09/2016 06:52 PM »
Isn't there a micro lensing event this month that can help find any planets around Proxima? As I recall there was also something similar in October 2014 and HST was taking observations. Wonder what was found.

Edit: found this, there is indeed an opportunity this month:

http://hubblesite.org/pubinfo/pdf/2013/22/pdf.pdf

If HST found something in 2014 maybe they're waiting till this month's observations to verify it?
« Last Edit: 02/09/2016 06:55 PM by Bubbinski »
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline Borklund

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Re: Pale Red Dot
« Reply #4 on: 02/09/2016 09:52 PM »
From the .pdf above:
Quote
With astrometric accuracies of 0.03 mas (achievable with HST spatial scanning), centroid shifts caused by Jovian planets are detectable at separations of up to 2′′.0 (corresponding to 2.6 AU at the distance of Proxima), and centroid shifts by Earth-mass planets are detectable within a small band of 8 mas (corresponnding to 0.01 AU) around the source trajectories. Jovian planets within a band of about 28 mas (corresponding to 0.036 AU) around the source trajectories would produce a brightening of the source by > 0.01 mag and could hence be detectable.
If I understand this correctly, microlensing would only be able to detect Jovian mass planets inside Proxima Centauri's habitable zone (?)

Offline kevin-rf

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Re: Pale Red Dot
« Reply #5 on: 02/10/2016 01:14 PM »
Reminds me of a chinese scifi book that is currently all the rage, Liu Cixin's "The Three-Body Problem"... A story about a planet in the Centauri system.

Anyway, I'll let the electrons return the thread to the proper rest state.
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Offline Bynaus

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Re: Pale Red Dot
« Reply #6 on: 02/10/2016 01:25 PM »
From the .pdf above:
Quote
With astrometric accuracies of 0.03 mas (achievable with HST spatial scanning), centroid shifts caused by Jovian planets are detectable at separations of up to 2′′.0 (corresponding to 2.6 AU at the distance of Proxima), and centroid shifts by Earth-mass planets are detectable within a small band of 8 mas (corresponnding to 0.01 AU) around the source trajectories. Jovian planets within a band of about 28 mas (corresponding to 0.036 AU) around the source trajectories would produce a brightening of the source by > 0.01 mag and could hence be detectable.
If I understand this correctly, microlensing would only be able to detect Jovian mass planets inside Proxima Centauri's habitable zone (?)

There are two effects of microlensing: centroid shifts and brightening. Centroid shifts caused by Jovian planets can be found up until separations of 2.6 AU, while for terrestrial planets, its out to 0.01 AU. Brightening is only detectable if there is a Jovian within 0.036 AU (but we already know there likely isn't one, unless it's orbiting Proxima perpendicular to the line of sight).

Offline Borklund

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Re: Pale Red Dot
« Reply #7 on: 02/10/2016 10:15 PM »
OK, so brightening microlensing could not detect a potentially habitable Earth or super-Earth inside Proxima's HZ in this case. If I understand the methods used by the Pale Red Dot team correctly, they have ruled out anything smaller than 3 times Earth's mass inside Proxima's H too, which is a bit of a bummer. Don't get me wrong, I'll take any and all confirmed exoplanets, but the potentially habitable ones are just that much more exciting.

Offline Alpha_Centauri

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Re: Pale Red Dot
« Reply #8 on: 02/10/2016 11:00 PM »
If I understand the methods used by the Pale Red Dot team correctly, they have ruled out anything smaller than 3 times Earth's mass inside Proxima's H too, which is a bit of a bummer.

Anything larger than ~2-3 times Earth-mass, smaller is still possible. But this is a limit on the minimum mass, msini.  Planets with a bit more true mass are still possible if the orbit is significantly inclined.
« Last Edit: 02/10/2016 11:09 PM by Alpha_Centauri »

Offline notsorandom

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Re: Pale Red Dot
« Reply #9 on: 02/11/2016 01:27 PM »
OK, so brightening microlensing could not detect a potentially habitable Earth or super-Earth inside Proxima's HZ in this case. If I understand the methods used by the Pale Red Dot team correctly, they have ruled out anything smaller than 3 times Earth's mass inside Proxima's H too, which is a bit of a bummer. Don't get me wrong, I'll take any and all confirmed exoplanets, but the potentially habitable ones are just that much more exciting.
It is amusing to me that since our techniques are better at finding bigger planets non-detection of planets increase the chance there are habitable planets. A gas giant stomping around the star systems would rule out any habitable planets so it is good that we haven't seen any. Likewise planets several times Earth's mass are questionable in terms of habitability so its good that we haven't seen any. There is still the possibility of an Earth sized planet in the habitable zone.

Offline Borklund

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Re: Pale Red Dot
« Reply #10 on: 02/11/2016 10:14 PM »
That sounds terrific. I will follow this intently!

Offline Star One

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Re: Pale Red Dot
« Reply #11 on: 02/15/2016 04:51 PM »
Another update.

INTERVIEW WITH SUZANNE AIGRAIN : ON THE SEARCH FOR NEARBY EARTH-LIKE EXOPLANETS

https://palereddot.org/interview-to-suzanne-aigrain-on-the-search-for-nearby-earth-like-exoplanets/

Offline redliox

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Re: Pale Red Dot
« Reply #12 on: 03/28/2016 09:48 PM »
Pale Red Dot is entering into it's final week now.  After that it will be a matter of processing data to see if Proxima Centauri has anything small circling beside it.
"Let the trails lead where they may, I will follow."
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Offline Ashley.Baldwin

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Re: Pale Red Dot
« Reply #13 on: 04/03/2016 12:36 PM »
I'm lucky enough to know the Lead behind Pale Red Dot , Guillem Anglada-Escude , and was able to play a small part in the initiative through the "Centauri Dreams"  website . In return we are a chosen regular updates site , straight from the team in return for this assistance. As far as I am aware , the best Doppler signal to date has a lower mass , msini and all , of just 1.2 Mearth with an 18 day period , so well within the Hab zone.

Offline redliox

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Re: Pale Red Dot
« Reply #14 on: 04/03/2016 07:14 PM »
As far as I am aware , the best Doppler signal to date has a lower mass , msini and all , of just 1.2 Mearth with an 18 day period , so well within the Hab zone.

How certain are they of this?  I'll be impressed if it's correct but I'd assume the odds for a planet beyond the hab zone are just as likely.  Either way, we all want to know what Proxima has circling itself.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline CuddlyRocket

Re: Pale Red Dot
« Reply #15 on: 04/03/2016 09:46 PM »
As far as I am aware , the best Doppler signal to date has a lower mass , msini and all , of just 1.2 Mearth with an 18 day period , so well within the Hab zone.

How certain are they of this?  I'll be impressed if it's correct but I'd assume the odds for a planet beyond the hab zone are just as likely.  Either way, we all want to know what Proxima has circling itself.

An Earth-sized planet within the HZ of the nearest (non-Sun) star to Earth would certainly cause a stir - science popularisers should get their soundbites ready for the inevitable media interest! How long is it likely to be before we find out?

Offline Star One

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Re: Pale Red Dot
« Reply #16 on: 04/18/2016 08:58 PM »
Pale Red Dot   ‏@Pale_red_dot

Campaign highlights 1 Proxima flares & rotates! Imagine the Sun bursting 10% brighter in minutes?by ASH2 #palereddot
Embedded image
2:02 a.m. - 16 Apr 2016
22 RETWEETS18 LIKES.

https://mobile.twitter.com/Pale_red_dot/status/721262539296927744

Offline Bubbinski

Re: Pale Red Dot
« Reply #17 on: 08/13/2016 01:19 AM »
Take it for what it's worth:

http://phys.org/news/2016-08-scientists-unveil-earth-like-planet.html

If this is really real......
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline the_other_Doug

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Re: Pale Red Dot
« Reply #18 on: 08/13/2016 02:03 AM »
Yep, but Proxima Centauri is a red dwarf, and so it's Goldilocks zone is small and close to the star.  Any Earth-sized planet in the zone will be tidally locked, which makes the sun-side a lot warmer than average, and the dark side a lot colder.  Any atmosphere would constantly rush around and the volatiles would get stuck in cold traps on the far side.  The twilight band might be livable, assuming any of the volatiles stay in a zone where it's not too warm, and not too cold, for liquid water.

As nice as it would be to find Earthlike worlds anywhere, the ones orbiting red dwarf stars are likely to have difficult conditions for life, or large amount of liquid water, due to the tidal locking issue.  It will be far more interesting to find an Earthlike world orbiting in the habitable zone of a sun-like star...
-Doug  (With my shield, not yet upon it)

Offline meekGee

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Re: Pale Red Dot
« Reply #19 on: 08/13/2016 03:25 AM »
All true, but there are certain advantages to twilight zones that might make inhabitants thereof wonder if life can really be possible in a planet whose rotation axis does not coincide with its radius vector...

I mean, on such a planet you'd have huge differences in temperature and lighting conditions every few hours!!!  Creatures on such planets might have to develop extreme mechanisms like a suspension of body activities during the cold, dark hours..... (shudder)

And if that axis of rotation is tilted with respect to the ecliptic, my god, you'd have yearly cycles super-imposed over the daily cycles, and sometimes you'd have more darkness than light, and sometimes the other way around....

How could life ever evolve to function in such conditions?

Maybe, these creatures would suppose, maybe life could find refuge in one of the poles, where conditions must be more hospitable...
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