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 hr with ephemeris T [BJD] =2454964.57375+0.00060–0.00082 + N*0.837495+0.000004–0.000005 days and (2) a 376 ± 9 ppm dimming lasting 6.86 ± 0.07 hr with ephemeris T [BJD] =2454971.6761+0.0020–0.0023 + N*45.29485+0.00065–0.00076 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 T
eff = 5627 ± 44 K, M
= 0.895 ± 0.060 M
☉, and R
= 1.056 ± 0.021 R
☉. 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: M
P = 4.56+1.17–1.29M
⊕, R
P = 1.416+0.033–0.036R
⊕, and ρP = 8.8+2.1–2.9 g cm–3. 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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