Kepler-186 : 5 planet system with Earth-sized planet in the HZ

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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by Mongo on 18th April 2014, 9:01 pm

All of the planets on that chart transit their primaries, that is how we have their diameters. In addition, RV was used to determine their masses, which is how they were verified as planets, and not brown dwarfs. And since they are known to transit their primaries, we know that the masses determined by RV are the actual masses. So I still don't see your point. I think you misunderstand the data.
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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by Sirius_Alpha on 18th April 2014, 9:57 pm

You can compare planets with minimum masses to planets with just radii by simply extrapolating what you know about mass-radius relations. All of the planets with minimum masses > 3 ME where we have measured radii have low densities (save for planets close enough to the star to have lost a considerable envelope). So it's not unreasonable to look at HD 40307 g, GJ 667Cc, and HD 85512 b and evaluate their habitability as being less than that of, for example, Kepler-186f.

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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by Led_Zep on 19th April 2014, 5:52 pm

http://www.nasa.gov/sites/default/files/files/kepler186_main_final.pdf

Title: An Earth-sized Planet in the Habitable Zone of a Cool Star

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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by ThinkerX on 19th April 2014, 8:51 pm

Nice chart, Led Zep.

More like it for other possible habitable planets...especially ones not likely to be mini-Neptune's?

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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by Sirius_Alpha on 23rd April 2014, 8:30 pm

Now on arXiv.

An Earth-sized Planet in the Habitable Zone of a Cool Star
http://arxiv.org/abs/1404.5667

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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by Sirius_Alpha on 28th October 2014, 9:18 pm

Tidal evolution in multiple planet systems: application to Kepler-62 and Kepler-186
http://arxiv.org/abs/1410.7428

They find that if an undetected sixth planet exists between Kepler-186 e and f, the planet requires a mass less than that of Earth to have avoided producing detectable changes in the inclination of the f planet.

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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by tommi59 on 29th October 2014, 4:25 am

Does not matter what period I mean AU will have such sub earth planet ? Closer to e or f ?
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Re: Kepler-186 : 5 planet system with Earth-sized planet in the HZ

Post by Lazarus on 29th October 2014, 3:25 pm

According to the paper linked in Led_Zep's post earlier in this thread, the predicted location for the additional planet would be close to the geometric mean of the orbits of e and f, around 0.2 AU. Not sure what they used for the stability simulations, but as it seems to be the same group of people who wrote that earlier paper I would guess they tested planets near that location.
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