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Kepler 11 6 planets system (Read 13629 times)
frankuitaalst
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Kepler 11 6 planets system
02/03/11 at 09:37:58
 
Inputing the basic data from  
http://exoplanet.eu/star.php?st=Kepler-11 gives the following .gsim file  
I've set the not known parameters at random in this simulation .  
The system looks weird , to be honest . It seems I can't get the right "view" .  
Somebody knows whats happening here ?  
BTW : I have no idea how the inclination ,close to 90 for every planet , is defined for this system .  
 
Edit : I have renewed the sim with the Longitude of ascending node set to 0 . Here's the sim . Looks better now
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« Last Edit: 02/03/11 at 12:18:09 by frankuitaalst »  
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Re: Kepler 11 6 planets system
Reply #1 - 02/03/11 at 10:09:54
 
the inclination is in respect to our ecliptic I believe and not the systems. If I am remembering all I've read about extra-solar planet data.
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Re: Kepler 11 6 planets system
Reply #2 - 02/03/11 at 12:18:32
 
Inclination is measured from vertical. (0 degrees would be looking at the system directly from above). An inclination of 90 degrees means we're looking at the system edge on. See http://astro.unl.edu/naap/ebs/animations/ebs.html for an interactive example (of eclipsing binary systems).
 
If the orbit is at 90 degrees, that means the planet's crossing the entire radius of the star, from centre of one limb to the centre of the other. If it's say 88 degrees, then the orbit is tilted a bit, and the planet's path across the star is a chord. I think that also means that the planet orbit is inclined by 2 degrees (=90-88) to our point of view?
 
You could just assume that they're all in the same plane anyway, I guess?
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frankuitaalst
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Re: Kepler 11 6 planets system
Reply #3 - 02/03/11 at 12:23:27
 
I think you're right doctor .  
Makes sense . The statement about the transits makes also sense if you look at the sim abpve , zoom in on the sun and watch how  the tiny little dots transit the solar disc .  
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Re: Kepler 11 6 planets system
Reply #4 - 02/03/11 at 13:52:28
 
Yikes, I didn't realise B and C were so close to eachother!
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Re: Kepler 11 6 planets system
Reply #5 - 02/05/11 at 01:27:33
 
Personally I think this star is in good support of the fission theory of planetary creation. Some stars collapse down from a gas and dust cloud of about a parsec in diameter. At some point they lose angular momentum, and half their mass by the ejection of an equatorial disk. they continue to collapse until they reach a critical density, then they can throw off a series of proto planets, of about Jupiter mass. The rocky metallic cores will be about Earth/Venus mass. The inner proto planets will then lose their atmospheres, as indeed seems to be happening here.
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Re: Kepler 11 6 planets system
Reply #6 - 02/05/11 at 01:48:14
 
I doubt that anything here can't be explained by Migration and orbital interactions.  
 
Kepler 11b at least is interesting - it's 12,334 km in radius (about twice that of Earth), and 4.27 earth masses - that gives it a bulk density of 3250 kg/m. Either it's a rocky planet with a thick hydrogen/helium atmosphere, or it's a panthalassic world (a rocky planet surrounded by a layer of water hundreds of km thick and most likely a dense atmosphere of water vapour and possibly other gases).
 
11f is even weirder - 16,345 km radius, only 2.3 earth masses, which means its density is 750 kg/m?! That's only slightly denser than Saturn, it really must be just a ball of hydrogen and helium! 11d is similar too (more massive though, but density is 825 kg/m)
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Re: Kepler 11 6 planets system
Reply #7 - 02/05/11 at 03:32:55
 
I don't think we can get ourselves a mallet and smash all discovered planetary systems into some sort of modified, or otherwise, "Bode's law". Actually I cannot load that sim, it just stalled the simulator. It might be fun to stick a few resonant planets in there and see what happens to them.
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Re: Kepler 11 6 planets system
Reply #8 - 02/05/11 at 04:16:04
 
Quote from EDG on 02/05/11 at 01:48:14:
I doubt that anything here can't be explained by Migration and orbital interactions.

Kepler 11b at least is interesting - it's 12,334 km in radius (about twice that of Earth), and 4.27 earth masses - that gives it a bulk density of 3250 kg/m. Either it's a rocky planet with a thick hydrogen/helium atmosphere, or it's a panthalassic world (a rocky planet surrounded by a layer of water hundreds of km thick and most likely a dense atmosphere of water vapour and possibly other gases).

11f is even weirder - 16,345 km radius, only 2.3 earth masses, which means its density is 750 kg/m?! That's only slightly denser than Saturn, it really must be just a ball of hydrogen and helium! 11d is similar too (more massive though, but density is 825 kg/m)

 
Interesting stuff indeed . The question that arises to me is how they can estimate a planets mass by transit observation . In the basic article I read, I think , they "calcualted" the individual masses from the perturbations of the individual orbits . Mmn hard job , even with the supercomputers used to analyse the stability of the system . On the other hand , this reference seems to indicate that a power law between Mass and Diameter may be proposed of even used .  
http://arxiv.org/PS_cache/arxiv/pdf/1102/1102.0543v1.pdf.  
This idea doesn't correspond with the data mentionned in the post for this system .
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« Last Edit: 02/05/11 at 10:28:52 by frankuitaalst »  
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Re: Kepler 11 6 planets system
Reply #9 - 02/05/11 at 05:58:01
 
This will probably sound like a really thick question to you guys but I'll ask it anyway.  embarrassed It's age?
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Re: Kepler 11 6 planets system
Reply #10 - 02/05/11 at 07:02:39
 
Now I'm totally confused  undecided For those planets to have migrated in, there must be a third massive body. Then those planets will be in almost perfectly circular orbits but inclined at close to ninety degrees to the sun's equatorial plane. Is there a cut off point, where this stops oscillating?
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Re: Kepler 11 6 planets system
Reply #11 - 02/05/11 at 12:11:50
 
They would probably have migrated in either by gas drag (interacting with gas in the protoplanetary disk) or accretion drag (transfer of angular momentum due to collisions with protoplanets). You don't need a "third massive body".
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Re: Kepler 11 6 planets system
Reply #12 - 02/07/11 at 02:17:32
 
A few of the sources of my confusion here. I'd been confused by the inclination angle but it makes sense to give that angle in terms of the Kepler telescope. So that one's sorted.  
 
Like everyone else, I'd read the science articles and I'd come away with the idea that we were talking about another dwarf star, with close in planets. I assume that the science writers were given a briefing which talked about these stars first then went on to talk about Kepler 11. Result, they nodded off and came away with the idea that it was yet another dwarf.
 
It's not a dwarf, it should stay on the main sequence just a little longer than we will. It's age has got me confused. I'd thought that the spectrum of the star should give us a date for when it joined the main sequence, a bit more precise than plus or minus two billion years.
 
So we're talking about a middle to old age star, which has planets which look like protoplanets. They should have lost their atmospheres. They shouldn't have almost perfect circular orbits.  
 
If the Kozai effect has brought them in very fast, then another hidden body would have had to be at almost ninety degrees to the system. I think that would be highly unlikely but not impossible for one case. However there seems to be loads of giant planets very close in. it doesn't make sense to me at all  embarrassed
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Re: Kepler 11 6 planets system
Reply #13 - 02/07/11 at 11:04:24
 
Quote from Bob on 02/07/11 at 02:17:32:
Like everyone else, I'd read the science articles and I'd come away with the idea that we were talking about another dwarf star, with close in planets. I assume that the science writers were given a briefing which talked about these stars first then went on to talk about Kepler 11. Result, they nodded off and came away with the idea that it was yet another dwarf.

It's not a dwarf, it should stay on the main sequence just a little longer than we will. It's age has got me confused. I'd thought that the spectrum of the star should give us a date for when it joined the main sequence, a bit more precise than plus or minus two billion years.

So we're talking about a middle to old age star, which has planets which look like protoplanets. They should have lost their atmospheres. They shouldn't have almost perfect circular orbits.

 
I'm not sure where you're getting confused here - it IS a "dwarf". Kepler-11 is a yellow G V main sequence star like the sun. Its effective temperature is 5680K, metallicity is solar, radius is 1.1 Sols, mass is 0.95 Sols, and the star is between 6 and 10 billion years old. Our own sun will stay on the main sequence for about 10 billion years, this star is less massive and formed a few billion years before our sun did.  
 
Why do you think it's not a main sequence star?
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Re: Kepler 11 6 planets system
Reply #14 - 02/07/11 at 12:34:25
 
Oops, my mistake,  embarrassed I've been labouring under the impression that dwarf stars were quite a bit less massive than Sol. Finding out hat Sol itself is a dwarf star I take as a a blow to my self esteem. Though I never said this thing is not a main sequence star.  I expressly said that it will reside on the main sequence a little longer than the sun.
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