Kepler's first rocky planet: Kepler-10b

The Astrophysical Journal (Impact Factor: 5.99). 02/2011; 729(1). DOI: 10.1088/0004-637X/729/1/27
Source: arXiv


NASA's Kepler Mission uses transit photometry to determine the frequency of
earth-size planets in or near the habitable zone of Sun-like stars. The mission
reached a milestone toward meeting that goal: the discovery of its first rocky
planet, Kepler-10b. Two distinct sets of transit events were detected: 1) a 152
+/- 4 ppm dimming lasting 1.811 +/- 0.024 hours with ephemeris
T[BJD]=2454964.57375+N*0.837495 days and 2) a 376 +/- 9 ppm dimming lasting
6.86 +/- 0.07 hours with ephemeris T[BJD]=2454971.6761+N*45.29485 days.
Statistical tests on the photometric and pixel flux time series established the
viability of the planet candidates triggering ground-based follow-up
observations. Forty precision Doppler measurements were used to confirm that
the short-period transit event is due to a planetary companion. The parent star
is bright enough for asteroseismic analysis. Photometry was collected at
1-minute cadence for >4 months from which we detected 19 distinct pulsation
frequencies. Modeling the frequencies resulted in precise knowledge of the
fundamental stellar properties. Kepler-10 is a relatively old (11.9 +/- 4.5
Gyr) but otherwise Sun-like Main Sequence star with Teff=5627 +/- 44 K,
Mstar=0.895 +/- 0.060 Msun, and Rstar=1.056 +/- 0.021 Rsun. Physical models
simultaneously fit to the transit light curves and the precision Doppler
measurements yielded tight constraints on the properties of Kepler-10b that
speak to its rocky composition: Mpl=4.56 +/- 1.29 Mearth, Rpl=1.416 +/- 0.036
Rearth, and density=8.8 +/- 2.9 gcc. Kepler-10b is the smallest transiting
exoplanet discovered to date.

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    • "These low densities indicate substantial envelopes of light gases such as H and He or possibly H 2 O and H. Could it be that these " super-Earths " could not lose their initial proto-atmospheres and that they are, in fact, " mini-Neptunes " ? In fact, the only observed " super-Earths " with higher densities which indicate rocky bodies such as the CoRoT-7b (Léger et al. 2009), , Kepler-10b (Batalha et al. 2011), Kepler-18b or Kepler-20b (Borucki et al. 2011) are much closer to their star, at a distance where really strong atmospheric escape is expected. "
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    • "Exoplanet surveys have already discovered the first rocky, strongly irradiated exoplanets: Corot 7b (Léger et al. 2009) and Kepler 10b (Batalha et al. 2011). A whole population of hot planets with minimum masses below 10 Earth masses, consistent with rocky planet models (super-Earths) has already been detected. "
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