Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

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Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Sirius_Alpha on 18th April 2013, 2:13 pm

Waiting on the paper or something.
http://www.cnn.com/2013/04/18/us/planet-discovery/

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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Edasich on 18th April 2013, 3:11 pm

In the meantime Kepler website's confirmed planet count is updated to 122 planets, including Kepler-62 and 69's systems.

http://kepler.nasa.gov/Mission/discoveries/

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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Daniel on 18th April 2013, 3:47 pm

Kepler-69c is KOI 172.02
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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Lazarus on 18th April 2013, 5:24 pm

From Kepler website discovery table:

Star: R = 0.93 R, Teff = 5638 K
Planet c: a = 0.64 AU

Insolation = 0.93^2 * (5638 / 5778)^4 / 0.64^2 = 1.91 times Earth.

In comparison, our solar system's well-known habitable planet Venus, semimajor axis 0.723 AU, receives an insolation of

1 / 0.723^2 = 1.91 times Earth.

Exact match*! BINGO!!!

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* (to 3 significant figures anyway)
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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Led_Zep on 18th April 2013, 10:16 pm

Paper from arXiv :

http://arxiv.org/abs/1304.4941

A super-Earth-sized planet orbiting in or near the habitable zone around Sun-like star

We present the discovery of a super-earth-sized planet in or near the habitable zone of a sun-like star. The host is Kepler-69, a 13.7 mag G4V-type star. We detect two periodic sets of transit signals in the three-year flux time series of Kepler-69, obtained with the Kepler spacecraft. Using the very high precision Kepler photometry, and follow-up observations, our confidence that these signals represent planetary transits is >99.1%. The inner planet, Kepler-69b, has a radius of 2.24+/-0.4 Rearth and orbits the host star every 13.7 days. The outer planet, Kepler-69c, is a super-Earth-size object with a radius of 1.7+/-0.3 Rearth and an orbital period of 242.5 days. Assuming an Earth-like Bond albedo, Kepler-69c has an equilibrium temperature of 299 +/- 19 K, which places the planet close to the habitable zone around the host star. This is the smallest planet found by Kepler to be orbiting in or near habitable zone of a Sun-like star and represents an important step on the path to finding the first true Earth analog.
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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by tommi59 on 19th April 2013, 1:50 am

Yes lazarus we know that but condition on venus are special and other planets are totally different but insolation slightly high for me though
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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Lazarus on 19th April 2013, 12:45 pm

Conditions are indeed special on Venus: the surprisingly cold surface temperatures are the result of it being highly reflective thanks to the global clouds and also because it has (almost) no water in its atmosphere. If it was less reflective or had more water (a very good greenhouse gas) in its atmosphere the conditions would probably be quite a bit hotter.
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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Led_Zep on 14th May 2013, 10:59 pm

http://arxiv.org/abs/1305.2933

A Potential Super-Venus in the Kepler-69 System

Transiting planets have greatly expanded and diversified the exoplanet field. These planets provide greater access to characterization of exoplanet atmospheres and structure. The Kepler mission has been particularly successful in expanding the exoplanet inventory, even to planets smaller than the Earth. The orbital period sensitivity of the Kepler data is now extending into the Habitable Zones of their host stars, and several planets larger than the Earth have been found to lie therein. Here we examine one such proposed planet, Kepler-69c. We provide new orbital parameters for this planet and an in-depth analysis of the Habitable Zone. We find that, even under optimistic conditions, this 1.7 R earth planet is unlikely to be within the Habitable Zone of Kepler-69. Furthermore, the planet receives an incident flux of 1.91 times the solar constant, which is similar to that received by Venus. We thus suggest that this planet is likely a super-Venus rather than a super-Earth in terms of atmospheric properties and habitability, and we propose follow-up observations to disentangle the ambiguity
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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

Post by Lazarus on 15th May 2013, 2:03 pm

What did I say? Razz
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Re: Kepler-69: Two-planet system with a super-Earth on inner edge of of the HZ

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