Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler
Abstract
We report the distribution of planets as a function of planet radius (R_p), orbital period (P), and stellar effective temperature (Teff) for P < 50 day orbits around GK stars. These results are based on the 1,235 planets (formally "planet candidates") from the Kepler mission that include a nearly complete set of detected planets as small as 2 Earth radii (Re). For each of the 156,000 target stars we assess the detectability of planets as a function of R_p and P. We also correct for the geometric probability of transit, R*/a. We consider first stars within the "solar subset" having Teff = 4100-6100 K, logg = 4.0-4.9, and Kepler magnitude Kp < 15 mag. We include only those stars having noise low enough to permit detection of planets down to 2 Re. We count planets in small domains of R_p and P and divide by the included target stars to calculate planet occurrence in each domain. Occurrence of planets varies by more than three orders of magnitude and increases substantially down to the smallest radius (2 Re) and out to the longest orbital period (50 days, ~0.25 AU) in our study. For P < 50 days, the radius distribution is given by a power law, df/dlogR= k R^\alpha. This rapid increase in planet occurrence with decreasing planet size agrees with core-accretion, but disagrees with population synthesis models. We fit occurrence as a function of P to a power law model with an exponential cutoff below a critical period P_0. For smaller planets, P_0 has larger values, suggesting that the "parking distance" for migrating planets moves outward with decreasing planet size. We also measured planet occurrence over Teff = 3600-7100 K, spanning M0 to F2 dwarfs. The occurrence of 2-4 Re planets in the Kepler field increases with decreasing Teff, making these small planets seven times more abundant around cool stars than the hottest stars in our sample. [abridged]
Keywords
Cite
@article{arxiv.1103.2541,
title = {Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler},
author = {Andrew W. Howard and Geoffrey W. Marcy and Stephen T. Bryson and Jon M. Jenkins and Jason F. Rowe and Natalie M. Batalha and William J. Borucki and David G. Koch and Edward W. Dunham and Thomas N. Gautier and Jeffrey Van Cleve and William D. Cochran and David W. Latham and Jack J. Lissauer and Guillermo Torres and Timothy M. Brown and Ronald L. Gilliland and Lars A. Buchhave and Douglas A. Caldwell and Jorgen Christensen-Dalsgaard and David Ciardi and Francois Fressin and Michael R. Haas and Steve B. Howell and Hans Kjeldsen and Sara Seager and Leslie Rogers and Dimitar D. Sasselov and Jason H. Steffen and Gibor S. Basri and David Charbonneau and Jessie Christiansen and Bruce Clarke and Andrea Dupree and Daniel C. Fabrycky and Debra A. Fischer and Eric B. Ford and Jonathan J. Fortney and Jill Tarter and Forrest R. Girouard and Matthew J. Holman and John Asher Johnson and Todd C. Klaus and Pavel Machalek and Althea V. Moorhead and Robert C. Morehead and Darin Ragozzine and Peter Tenenbaum and Joseph D. Twicken and Samuel N. Quinn and Howard Isaacson and Avi Shporer and Philip W. Lucas and Lucianne M. Walkowicz and William F. Welsh and Alan Boss and Edna Devore and Alan Gould and Jeffrey C. Smith and Robert L. Morris and Andrej Prsa and Timothy D. Morton},
journal= {arXiv preprint arXiv:1103.2541},
year = {2015}
}
Comments
Submitted to ApJ, 22 pages, 10 figures