Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets

Status Report From:
Posted: Wednesday, January 22, 2014


We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars.

Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities for all of the transiting planets (41 of 42 have a false-positive probability under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than 3X the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition.

We identify 6 planets with densities above 5 g/cc, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ~2 R_earth. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).

Geoffrey W. Marcy, Howard Isaacson, Andrew W. Howard, Jason F. Rowe, Jon M. Jenkins, Stephen T. Bryson, David W. Latham, Steve B. Howell, Thomas N. Gautier III, Natalie M. Batalha, Leslie A. Rogers, David Ciardi, Debra A. Fischer, Ronald L. Gilliland, Hans Kjeldsen, Jorgen Christensen-Dalsgaard, Daniel Huber, William J. Chaplin, Sarbani Basu, Lars A. Buchhave, Samuel N. Quinn, William J. Borucki, David G. Koch, Roger Hunter, Douglas A. Caldwell, Jeffrey Van Cleve, Rea Kolbl, Lauren M. Weiss, Erik Petigura, Sara Seager, Timothy Morton, John Asher Johnson, Sarah Ballard, Chris Burke, William D. Cochran, Michael Endl, Phillip MacQueen, Mark E. Everett, Jack J. Lissauer, Eric B. Ford, Guillermo Torres, Francois Fressin, Timothy M. Brown, Jason H. Steffen, David Charbonneau, Gibor S. Basri, et al. (57 additional authors not shown) You must enabled JavaScript to view entire author list. (Submitted on 16 Jan 2014)

Comments: 94 pages, 55 figures, 25 tables. Accepted by ApJS

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Journal reference: Geoffrey W. Marcy et al. 2014 ApJS 210 20 DOI: 10.1088/0067-0049/210/2/20

Cite as: arXiv:1401.4195 [astro-ph.EP]

(or arXiv:1401.4195v1 [astro-ph.EP] for this version)

Submission history From: Howard Isaacson [view email] [v1] Thu, 16 Jan 2014 22:54:55 GMT (2876kb)


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