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slaver0110
2012-Jan-12, 06:32 PM
Came across this link today in the Orbiter Forum, and thought I'd share it.
http://www.futurity.org/top-stories/odd-eclipse-reveals-saturn-on-steroids/

Just out of curiosity, is this the first time astronomers have found evidence of ringed extrasolar planets, or has there been evidence of others?

Not sure if it's permitted to link to another forum with a pertinent thread, (so Mods if this is against the rules, please forgive), but here is the link to the discussion in the Orbiter Furum:

http://orbiter-forum.com/showthread.php?t=25919

Cheers!

IsaacKuo
2012-Jan-12, 09:28 PM
Aliens! No, not really. The system is too young for that, unless the aliens came from another star system.

But I'll be honest--every time something like this is discovered, my first thought it to ponder whether it matches a potential alien artifcat. In this case, I was pondering the possibility of an extensive SBSP system or collection of orbital space colonies. But no...the characteristics of this seem entirely natural.

SagittariusAStar
2012-Jan-12, 09:29 PM
Astronomers have never found a ringed extrasolar planet.

And they still haven't.

This story is based on an incredibly misleading press release. The actual scientific paper, which first appeared on Arxiv in August (!), is much more circumspect:
http://arxiv.org/abs/1108.4070 .

No one knows the mass of this "planet." The star this "planet" goes around is only 16 million years old. In all likelihood, this "planet" is really a young star with a disk

slaver0110
2012-Jan-12, 11:10 PM
Astronomers have never found a ringed extrasolar planet.

And they still haven't.

This story is based on an incredibly misleading press release. The actual scientific paper, which first appeared on Arxiv in August (!), is much more circumspect:
http://arxiv.org/abs/1108.4070 .

No one knows the mass of this "planet." The star this "planet" goes around is only 16 million years old. In all likelihood, this "planet" is really a young star with a disk

Thanks for the clarification Sag; I wasn't aware of the press release associated with the paper.
With that being said, is it fair to say that it is not (currently) possible to determine whether a planet at such a distance has rings?

SagittariusAStar
2012-Jan-14, 08:45 PM
Kepler should be able to detect a planet with large rings if the planet passes in front of its star: see this paper by Jason Barnes and Jonathan Fortney: http://adsabs.harvard.edu/abs/2004ApJ...616.1193B .

However, Kepler tends to find planets close to their stars, and all ringed planets in our solar system are far from the star. If you moved Saturn close to the Sun, its rings--which are made of ice--would vaporize.

Doodler
2012-Jan-16, 02:20 PM
Kepler should be able to detect a planet with large rings if the planet passes in front of its star: see this paper by Jason Barnes and Jonathan Fortney: http://adsabs.harvard.edu/abs/2004ApJ...616.1193B .

However, Kepler tends to find planets close to their stars, and all ringed planets in our solar system are far from the star. If you moved Saturn close to the Sun, its rings--which are made of ice--would vaporize.

What about dust/rock rings? Earth spent a little time as a ringed planet following the impact that created the Moon, so its not impossible for a close in ringed planet to occur.

whimsyfree
2012-Jan-17, 03:59 AM
What about dust/rock rings? Earth spent a little time as a ringed planet following the impact that created the Moon, so its not impossible for a close in ringed planet to occur.

True but such rings aren't likely to be long lived. A massive ring will coalesce into a moon (or two) while a thin one is likely to get ground down by collisions then blown away by the stellar wind.

IsaacKuo
2012-Jan-18, 08:51 AM
True but such rings aren't likely to be long lived. A massive ring will coalesce into a moon (or two) while a thin one is likely to get ground down by collisions then blown away by the stellar wind.
Huh? Just why do you think Saturn's rings don't coalesce into a moon?

Whether a ring coalesces into a moon has to do with the Roche limit and not whether it's made of ice.

Doodler
2012-Jan-18, 12:48 PM
True but such rings aren't likely to be long lived. A massive ring will coalesce into a moon (or two) while a thin one is likely to get ground down by collisions then blown away by the stellar wind.
Define long lived?

Also, it's a young system, those planets are probably still coalescing, to some degree. Alternatively, we could just have happened to discover it at just the right time to observe a short lived ring system.

whimsyfree
2012-Jan-20, 05:52 AM
Huh? Just why do you think Saturn's rings don't coalesce into a moon?


Their mass is small and they are mostly within the Roche limit.


Whether a ring coalesces into a moon has to do with the Roche limit and not whether it's made of ice.

I didn't address that question but the composition of particles does affect whether they coalesce. Read the literature on planet formation.

IsaacKuo
2012-Jan-20, 06:07 AM
Their mass is small and they are mostly within the Roche limit.
It is because they are mostly within the Roche limit that their mass is small. This prevents formation into a moon because that hypothetical moon would rip itself apart into small bits.

This applies whether the ring is composed of ice or composed of dust/rock.

I didn't address that question but the composition of particles does affect whether they coalesce. Read the literature on planet formation.
You made a claim that massive dust/rock ring would coalesce into a moon. But it simply would not do so, if it were within the Roche limit.

whimsyfree
2012-Jan-23, 06:37 AM
It is because they are mostly within the Roche limit that their mass is small.


You misinterpreted. By "their mass" I meant their collective total mass.



You made a claim that massive dust/rock ring would coalesce into a moon. But it simply would not do so, if it were within the Roche limit.

No and it wouldn't if it were close to the limits of the Hill zone either, or within the atmosphere etc. I omit obvious qualifications. In the case you refer to the loss process would involve both solar tides and collisional grinding until the particles were small enough for photon pressure, electrostatic and magnetic forces to be significant. You will notice that Earth has no disk. Nor do any of the other terrestrial planets despite a history of large impacts some of which must surely have sent ejecta into orbit.

IsaacKuo
2012-Jan-24, 03:28 PM
You misinterpreted. By "their mass" I meant their collective total mass.
Either way, it doesn't matter. Whether "their mass" means the individual masses of the pieces or the total mass of all of them, they simply will not coalesce into a single moon. This directly contradicts your claim that they would.

No and it wouldn't if it were close to the limits of the Hill zone either, or within the atmosphere etc. I omit obvious qualifications.
Since this was about a hypothetical ringed planet similar to Saturn, the Roche limit is directly relevant. Your claim was that a massive ring would coalesce into one (or two) moons, but it would not. The amount of mass in the rings would be utterly irrelevant.

In the case you refer to the loss process would involve both solar tides and collisional grinding until the particles were small enough for photon pressure, electrostatic and magnetic forces to be significant. You will notice that Earth has no disk. Nor do any of the other terrestrial planets despite a history of large impacts some of which must surely have sent ejecta into orbit.
So what? This is a "just so" story. All of the gas giants have at least a minimal ring. Only one of them has an extensive ring system.

According to your "just so" thinking, is this merely because gas giants are far away from the Sun? What about Pluto? It has no ring either. Instead, it seems to have a collision formed moon, like Earth. Why doesn't it have a ring? It obviously has suffered a history of impacts, as evidenced by the existence of Charon.

whimsyfree
2012-Jan-24, 09:10 PM
Either way, it doesn't matter. Whether "their mass" means the individual masses of the pieces or the total mass of all of them, they simply will not coalesce into a single moon. This directly contradicts your claim that they would.

Since this was about a hypothetical ringed planet similar to Saturn, the Roche limit is directly relevant.


Really? I thought we were talking about terrestrial planets. How can they be similar to Saturn?


Your claim was that a massive ring would coalesce into one (or two) moons, but it would not. The amount of mass in the rings would be utterly irrelevant.

So your claim is that a massive ring outside the Roche limit would not coalesce? What is the standard explanation for the formation of Earth's moon?



So what? This is a "just so" story.

What does that mean?



All of the gas giants have at least a minimal ring. Only one of them has an extensive ring system.

According to your "just so" thinking, is this merely because gas giants are far away from the Sun? What about Pluto? It has no ring either. Instead, it seems to have a collision formed moon, like Earth. Why doesn't it have a ring? It obviously has suffered a history of impacts, as evidenced by the existence of Charon.

I thought you were the one claiming rings wouldn't coalesce or dissipate so it's up to you to provide the explanation.

IsaacKuo
2012-Jan-24, 11:12 PM
Really? I thought we were talking about terrestrial planets. How can they be similar to Saturn?
Quoted in the post your originally replied to: "However, Kepler tends to find planets close to their stars, and all ringed planets in our solar system are far from the star. If you moved Saturn close to the Sun, its rings--which are made of ice--would vaporize."

(Emphasis added)

Doodler then suggested the possibility of dust/rock rings rather than ice rings.


So your claim is that a massive ring outside the Roche limit would not coalesce?

No. Don't be silly. I am refuting your claim that a massive ring would coalesce. In fact, it would not coalesce if it were within the Roche limit. You were replying to a post about a hypothetical close in Saturn with a rock ring, rather than an ice ring, so the Roche limit was directly relevant.

whimsyfree
2012-Jan-25, 03:27 AM
Quoted in the post your originally replied to: "However, Kepler tends to find planets close to their stars, and all ringed planets in our solar system are far from the star. If you moved Saturn close to the Sun, its rings--which are made of ice--would vaporize."


So what? Replies are to what was written, not what was quoted. Anyone can see the post in question (http://www.bautforum.com/showthread.php/126913-Extrasolar-ringed-planet-discovery?p=1980099#post1980099) and that it doesn't respond to what you claim it does. Why do you do this? No-one is going to be fooled by it.

IsaacKuo
2012-Jan-25, 07:07 AM
So what? Replies are to what was written, not what was quoted. Anyone can see the post in question (http://www.bautforum.com/showthread.php/126913-Extrasolar-ringed-planet-discovery?p=1980099#post1980099) and that it doesn't respond to what you claim it does. Why do you do this? No-one is going to be fooled by it.
Huh? I quoted exactly from what it (http://www.bautforum.com/showthread.php/126913-Extrasolar-ringed-planet-discovery?p=1979867#post1979867) responded to.

The bottom line is that the discussion is about whether a close in ringed planet is possible. You are either claiming it is impossible for a close in ringed planet to last very long, or you are claiming that it's impossible except for the obvious exceptions when it's possible but you didn't feel any need to mention that. Either you are wrong or unhelpful.

A long lived close in ringed planet is possible. As already suggested, a Saturn-like planet with a dust/rock ring rather than an ice ring would have a long lived ring. This ring would not coalesce into a large moon, as you claimed, because of the Roche limit.

I really don't know what point you think you're making.