Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates

Details Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates

2011-12-19

arxiv.org/abs/1112.4514v2

Astronomy and Astrophysics

Astrophysics

Earth and Planetary Astrophysics

accepted by ApJ, 58 pages, 12 figures revised Jan 2012 to correct table 2 and clarify planet parameter extraction

Scientific paper

We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASSJ19104752+4220194. We find a stellar effective temperature Teff=5455+-100K, a metallicity of [Fe/H]=0.01+-0.04, and a surface gravity of log(g)=4.4+-0.1. Combined with an estimate of the stellar density from the transit light curves we deduce a stellar mass of Mstar=0.912+-0.034 Msun and a stellar radius of Rstar=0.944^{+0.060}_{-0.095} Rsun. For three of the transit signals, our results strongly disfavor the possibility that these result from astrophysical false positives. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2e5 (Kepler-20b), 1e5 (Kepler-20c), and 1.1e3 (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavored by the achromaticity of the transit: From Spitzer data gathered at 4.5um, we infer a ratio of the planetary to stellar radii of 0.075+-0.015 (Kepler-20c) and 0.065+-0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70d and 1.91^{+0.12}_{-0.21} Rearth for Kepler-20b, 10.85 d and 3.07^{+0.20}_{-0.31} Rearth for Kepelr-20c, and 77.61 d and 2.75^{+0.17}_{-0.30} Rearth for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7\+-2.2 Mearth and 16.1+-3.5 Mearth, respectively, and we place an upper limit on the mass of Kepler-20d of 20.1 Mearth (2 sigma).

Affiliated with

Also associated with

No associations

Rating

Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Kepler-20: A Sun-like Star with Three Sub-Neptune Exoplanets and Two Earth-size Candidates will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-53960