Author Topic: Pale Red Dot  (Read 40869 times)

Online Alpha_Centauri

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Re: Pale Red Dot
« Reply #40 on: 08/14/2016 07:05 AM »
From what I heard, it wasn't the Pale Red Dot team who reported the finding.

Interestingly astronomer David Kipping said this, https://twitter.com/david_kipping/status/764581374099685376

Offline Ben the Space Brit

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Re: Pale Red Dot
« Reply #41 on: 08/14/2016 07:31 AM »
I'm wondering if anyone's keeping statistics here?

It seems to me that red dwarves are more likely to have planets than not. I'm wondering if it's going to turn out that the power of the primary (thus the intensity of the T-Tauri wind at fusion ignition) will have a big influence on whether the system has any native planets (as opposed to captured interstellar wanderers).
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Offline Star One

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Re: Pale Red Dot
« Reply #42 on: 08/14/2016 09:42 AM »
I would imagine the previous thread was deleted due to embargo-breaking, so this probably will be too. Seems a bit toothpaste-back-in-tube now, but that's the site-owners choice.

Especially as it's now been widely reported on both specialist and general news sites. Rather reminds me of the first LIGO announcement.

Offline Chris Bergin

Re: Pale Red Dot
« Reply #43 on: 08/14/2016 01:54 PM »
The other thread is gone for some reason (I don't know what).


We had five threads on this and including "I think this site is an alien wacko site but I'm linking it anyway" posts (come on ;))

We can have one thread....and there's about three merged into this one.

Offline redliox

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Re: Pale Red Dot
« Reply #44 on: 08/14/2016 07:31 PM »
The other thread is gone for some reason (I don't know what).


We had five threads on this and including "I think this site is an alien wacko site but I'm linking it anyway" posts (come on ;))

We can have one thread....and there's about three merged into this one.

The joys of forum managing, eh Chris?  ;)

Getting back to topic, the Pale Red Dot team isn't connected to the announcement, and on top of that we had the (likely) false alarm of a 'hot Earth' around Alpha Centauri B in the recent past.  The team whose announcing this Proxima discovery better have some good evidence.  Proxima has been thoroughly investigated; as an example PRD spent several months straight observing, which given a hypothetical Earth would be in a barely week-long orbit, should be ample to observe transits so long as you can meet the detection threshold and account for flare activity.  All that is pretty certain about Proxima regarding planets is that anything Neptune-size and larger has been discounted, especially in close orbits.  Given how, thanks largely to Kepler, we now know planets are indeed a common commodity for stars, it would be surprising NOT to find a planet around Proxima; we just need to verify if it can be Earthlike or not.
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Offline Star One

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Pale Red Dot
« Reply #45 on: 08/14/2016 08:25 PM »
The other thread is gone for some reason (I don't know what).


We had five threads on this and including "I think this site is an alien wacko site but I'm linking it anyway" posts (come on ;))

We can have one thread....and there's about three merged into this one.

The joys of forum managing, eh Chris?  ;)

Getting back to topic, the Pale Red Dot team isn't connected to the announcement, and on top of that we had the (likely) false alarm of a 'hot Earth' around Alpha Centauri B in the recent past.  The team whose announcing this Proxima discovery better have some good evidence.  Proxima has been thoroughly investigated; as an example PRD spent several months straight observing, which given a hypothetical Earth would be in a barely week-long orbit, should be ample to observe transits so long as you can meet the detection threshold and account for flare activity.  All that is pretty certain about Proxima regarding planets is that anything Neptune-size and larger has been discounted, especially in close orbits.  Given how, thanks largely to Kepler, we now know planets are indeed a common commodity for stars, it would be surprising NOT to find a planet around Proxima; we just need to verify if it can be Earthlike or not.

Looking online this leak appears to have already fired up interest in interstellar flight amongst the social media crowd, which is a positive.

As an aside I see Paul Gilster appears to have taken a vow of silence on this news.
« Last Edit: 08/14/2016 08:31 PM by Star One »

Offline Star One

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Pale Red Dot
« Reply #46 on: 08/15/2016 06:29 AM »
Just as a side point doesn't it appear that the term 'earth like' is getting especially horrible misused online & with the media in this case, and leads to people imaging a planet just like Earth but with red skies. When there's likely to be no evidence of anything like that at all. Maybe a better phrase could be found to be used by those making these discoveries?
« Last Edit: 08/15/2016 06:35 AM by Star One »

Offline redliox

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Re: Pale Red Dot
« Reply #47 on: 08/15/2016 06:33 AM »
Just as a side point doesn't it appear that the term 'earth like' is getting especially horrible misused online in this case and leads to people imaging a planet just like Earth just with red skies. When there's no likely to be no evidence of anything like that at all.

Agreed.  The bare minimum for an Earthlike planet should be a rocky planet with liquid water on the surface.  We certainly don't call Venus Earthlike as an example, nor Europa where the liquid water is under the surface.
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Offline Star One

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Pale Red Dot
« Reply #48 on: 08/15/2016 06:37 AM »
Just as a side point doesn't it appear that the term 'earth like' is getting especially horrible misused online in this case and leads to people imaging a planet just like Earth just with red skies. When there's no likely to be no evidence of anything like that at all.

Agreed.  The bare minimum for an Earthlike planet should be a rocky planet with liquid water on the surface.  We certainly don't call Venus Earthlike as an example, nor Europa where the liquid water is under the surface.

I suppose the problem is how do you condense for the modern reader the ideas that it's likely to be tidally locked to an active flare star and everything that's theorised around such conditions. I mean there's competing theories about something as basic as the habitability of red dwarf planetary systems in general, let alone individual planets around a particular star.
« Last Edit: 08/15/2016 06:40 AM by Star One »

Online jebbo

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Re: Pale Red Dot
« Reply #49 on: 08/15/2016 08:32 AM »
Agreed.  The bare minimum for an Earthlike planet should be a rocky planet with liquid water on the surface.  We certainly don't call Venus Earthlike as an example, nor Europa where the liquid water is under the surface.

I think there are serious problems for habitability around late-M dwarfs - they are very active in their early life and the models say they'll essentially lose their atmosphere and volatiles due to this.  Add in the effect of flares and I'd be surprised if this really is habitable ... but still VERY exciting as it is a great prospect for testing a lot of the competing theories.

On the leak, I suspect it could be about the Pale Red Dot campaign as they were into first round review stuff in early July, so end of August is feasible for paper acceptance.  [ And if they had a null result, I rather suspect they wouldn't be quite so careful over embargo etc. ]

--- Tony
« Last Edit: 08/15/2016 08:38 AM by jebbo »

Offline Star One

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Pale Red Dot
« Reply #50 on: 08/15/2016 09:45 AM »
Agreed.  The bare minimum for an Earthlike planet should be a rocky planet with liquid water on the surface.  We certainly don't call Venus Earthlike as an example, nor Europa where the liquid water is under the surface.

I think there are serious problems for habitability around late-M dwarfs - they are very active in their early life and the models say they'll essentially lose their atmosphere and volatiles due to this.  Add in the effect of flares and I'd be surprised if this really is habitable ... but still VERY exciting as it is a great prospect for testing a lot of the competing theories.

On the leak, I suspect it could be about the Pale Red Dot campaign as they were into first round review stuff in early July, so end of August is feasible for paper acceptance.  [ And if they had a null result, I rather suspect they wouldn't be quite so careful over embargo etc. ]

--- Tony

Isn't one theory that a planet could possibly stay habitable around a red dwarf if it started out with an incredible thick atmosphere. But then it would probably also need an active magnetic field which I think tidal locking would preclude.
« Last Edit: 08/15/2016 09:47 AM by Star One »

Online jebbo

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Re: Pale Red Dot
« Reply #51 on: 08/15/2016 09:55 AM »
Isn't one theory that a planet could possibly stay habitable around a red dwarf if it started out with an incredible thick atmosphere. But then it would probably also need an active magnetic field which I think tidal locking would preclude.

Yes, but (from memory) that relies on having a larger radius (>1.5Re) so there's a large initial H/He envelope ... there are also other models which rely on later inward migration into the HZ.

But we're speculating on very poor data that could easily be wrong - the initial Der Spiegel article is hardly detailed ;-)

--- Tony

Online Alpha_Centauri

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Re: Pale Red Dot
« Reply #52 on: 08/15/2016 09:59 AM »
On the leak, I suspect it could be about the Pale Red Dot campaign as they were into first round review stuff in early July, so end of August is feasible for paper acceptance.  [ And if they had a null result, I rather suspect they wouldn't be quite so careful over embargo etc. ]

--- Tony


Interestingly the palereddot team apparently said to discovermag that the leak wasn't from them. Doesn't mean it's not about them though I suppose. Also Interesting that the MOST satellite transit data is embargoed until around the same time...
« Last Edit: 08/15/2016 04:52 PM by Alpha_Centauri »

Offline redliox

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Re: Pale Red Dot
« Reply #53 on: 08/15/2016 10:02 AM »
Isn't one theory that a planet could possibly stay habitable around a red dwarf if it started out with an incredible thick atmosphere. But then it would probably also need an active magnetic field which I think tidal locking would preclude.

Yes, but (from memory) that relies on having a larger radius (>1.5Re) so there's a large initial H/He envelope ... there are also other models which rely on later inward migration into the HZ.

But we're speculating on very poor data that could easily be wrong - the initial Der Spiegel article is hardly detailed ;-)

--- Tony

Presuming Proxima DOES have a rocky planet in the habitable zone, we would be able to put these quandaries and theories to the test on whether or not M-dwarfs can be viable parents to Earthlike planets. 

Interestingly the palereddot team apparently said to discovermag that the leak wasn't from them. Doesn't mean it's not about them though I suppose. Also Interesting that MOST data is embargoed until around the same time...

The claim isn't from them is certain so far.  Whether Proxima has a planet remains uncertain.
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Online jebbo

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Re: Pale Red Dot
« Reply #54 on: 08/15/2016 10:14 AM »
Presuming Proxima DOES have a rocky planet in the habitable zone, we would be able to put these quandaries and theories to the test on whether or not M-dwarfs can be viable parents to Earthlike planets. 

Indeed! Very exciting if it proves to be true ...

Quote
Interestingly the palereddot team apparently said to discovermag that the leak wasn't from them. Doesn't mean it's not about them though I suppose. Also Interesting that MOST data is embargoed until around the same time...

The claim isn't from them is certain so far.  Whether Proxima has a planet remains uncertain.

I'm suspicious it's *about* them, regardless of the source as the original Der Spiegel article claims the discovery was made at La Silla, which correlates with the Pale Red Dot HARPS campaign and I'd be amazed if there were two uncoordinated HARPS runs for the same target so close together ...

--- Tony

Offline Star One

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« Reply #55 on: 08/15/2016 11:50 AM »
Has there been any second look study of Barnard's star for planets as that's another very close red dwarf? I can't find anything more recent than about 2012 online.
« Last Edit: 08/15/2016 11:56 AM by Star One »

Online Bynaus

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Re: Pale Red Dot
« Reply #56 on: 08/15/2016 07:29 PM »
Isn't one theory that a planet could possibly stay habitable around a red dwarf if it started out with an incredible thick atmosphere. But then it would probably also need an active magnetic field which I think tidal locking would preclude.

Yes, but (from memory) that relies on having a larger radius (>1.5Re) so there's a large initial H/He envelope ... there are also other models which rely on later inward migration into the HZ.

Well, as always - it depends.

There is work that shows that, at least for some stellar masses and initial eccentricities of the planet, a magnetic field is the natural outcome for an M dwarf planet, because tidal heating cools the core which, in turn, generates a magnetic field. See here: http://arxiv.org/abs/1509.07452

Then, a thick atmosphere could inhibit tidal locking, forcing (or "allowing", whichever you prefer) the planet to rotate "unbound" as is the case for Venus. See here: http://physicsworld.com/cws/article/news/2015/jan/15/exoplanets-could-avoid-tidal-locking-if-they-have-atmospheres (link to publication in article)

Finally, the atmosphere doesn't have to be "incredibly" thick (or made of H/He) to keep up habitable conditions on a planet around a red dwarf. It depends again on the exact conditions, but already a ca. 1 bar CO2 atmosphere on an Earth-sized planet should be enough to inhibit atmospheric collapse due to freeze-out on the night side (from a 1997! paper): http://crack.seismo.unr.edu/ftp/ftp/pub/gillett/joshi.pdf

So, in summary: it depends. I am sure that, once the Proxima paper is published, we will see detailed models exploring the possibility of the planet's habitability. If we are very lucky and there is a transit, we might even be able to refine these models to the point where they become believable and constraining. That would be something...
« Last Edit: 08/15/2016 07:30 PM by Bynaus »

Online jebbo

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Re: Pale Red Dot
« Reply #57 on: 08/15/2016 08:19 PM »
There is work that shows that, at least for some stellar masses and initial eccentricities of the planet, a magnetic field is the natural outcome for an M dwarf planet, because tidal heating cools the core which, in turn, generates a magnetic field. See here: http://arxiv.org/abs/1509.07452

Thanks, I hadn't read that one ... I was more focused on the desiccation problem (http://arxiv.org/abs/1605.00616).

Quote
So, in summary: it depends. I am sure that, once the Proxima paper is published, we will see detailed models exploring the possibility of the planet's habitability. If we are very lucky and there is a transit, we might even be able to refine these models to the point where they become believable and constraining. That would be something...

Yes, we are rather speculating in the dark ... and a transit would be fabulous (density and spectroscopy should constrain atmosphere models); without one, assuming the leak turns out to be accurate, I guess we'll have to wait for a star-shade.

--- Tony

Offline Star One

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Re: Pale Red Dot
« Reply #58 on: 08/15/2016 08:53 PM »
There is work that shows that, at least for some stellar masses and initial eccentricities of the planet, a magnetic field is the natural outcome for an M dwarf planet, because tidal heating cools the core which, in turn, generates a magnetic field. See here: http://arxiv.org/abs/1509.07452

Thanks, I hadn't read that one ... I was more focused on the desiccation problem (http://arxiv.org/abs/1605.00616).

Quote
So, in summary: it depends. I am sure that, once the Proxima paper is published, we will see detailed models exploring the possibility of the planet's habitability. If we are very lucky and there is a transit, we might even be able to refine these models to the point where they become believable and constraining. That would be something...

Yes, we are rather speculating in the dark ... and a transit would be fabulous (density and spectroscopy should constrain atmosphere models); without one, assuming the leak turns out to be accurate, I guess we'll have to wait for a star-shade.

--- Tony
Was this a microlensing observing campaign?

Offline CuddlyRocket

Re: Pale Red Dot
« Reply #59 on: 08/16/2016 02:45 AM »
The team whose announcing this Proxima discovery better have some good evidence.  Proxima has been thoroughly investigated; as an example PRD spent several months straight observing, which given a hypothetical Earth would be in a barely week-long orbit, should be ample to observe transits so long as you can meet the detection threshold and account for flare activity.

If the plane of the orbit is such that we're seeing it more or less edge on from our vantage point on Earth. Plenty of exoplanets discovered using the radial velocity or other methods don't transit at all.

Quote
All that is pretty certain about Proxima regarding planets is that anything Neptune-size and larger has been discounted, especially in close orbits.

Which - as I'm sure you appreciate but didn't explicitly state - doesn't rule out anything smaller than Neptune; or indeed anything larger with an orbital period longer than the period of observation.

Quote
Given how, thanks largely to Kepler, we now know planets are indeed a common commodity for stars, it would be surprising NOT to find a planet around Proxima; we just need to verify if it can be Earthlike or not.

Being pernickety (allowed in matters scientific!), it would be surprising for there not to be a planet around Proxima, but there are plenty of orbital configurations that would not be discoverable with our present techniques.

... and leads to people imaging a planet just like Earth but with red skies.

Red skies because it's orbiting a red dwarf? Another bit of public (if not your) confusion caused by astronomical terminology - which often seems as if it's designed to confuse! - not helped by all those artistic impressions etc showing red dwarfs as red etc. But if you're close enough to a red dwarf to see it as a disc, it'll appear white - as you'd expect for any object with a temperature in the thousands of degrees. If you were standing on an Earthlike planet orbiting Proxima, the skies and 'sun' would probably look pretty much the same as they do on Earth.

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