We present the confirmation of a small, moderately-irradiated (F = 155 +/- 7 Fearth) Neptune with a substantial gas envelope in a P=11.8728787+/-0.0000085-day orbit about a quiet, Sun-like G0V star Kepler-1655. Based on our analysis of the Kepler light curve, we determined Kepler-1655b's radius to be 2.213+/-0.082 Rearth. We acquired 95 high-resolution spectra with TNG/HARPS-N, enabling us to characterize the host star and determine an accurate mass for Kepler-1655b of 5.0+3.1/-2.8 Mearth via Gaussian-process regression. Our mass determination excludes an Earth-like composition with 98\% confidence. Kepler-1655b falls on the upper edge of the evaporation valley, in the relatively sparsely occupied transition region between rocky and gas-rich planets. It is therefore part of a population of planets that we should actively seek to characterize further.
@article{arxiv.1803.08820,
title = {An accurate mass determination for Kepler-1655b, a moderately-irradiated world with a significant volatile envelope},
author = {R. D. Haywood and A. Vanderburg and A. Mortier and H. A. C. Giles and M. López-Morales and E. D. Lopez and L. Malavolta and D. Charbonneau and A. Collier Cameron and J. L. Coughlin and C. D. Dressing and C. Nava and D. W. Latham and X. Dumusque and C. Lovis and E. Molinari and F. Pepe and A. Sozzetti and S. Udry and F. Bouchy and J. A. Johnson and M. Mayor and G. Micela and D. Phillips and G. Piotto and K. Rice and D. Sasselov and D. Ségransan and C. Watson and L. Affer and A. S. Bonomo and L. A. Buchhave and D. R. Ciardi and A. F. Fiorenzano and A. Harutyunyan},
journal= {arXiv preprint arXiv:1803.08820},
year = {2018}
}
Comments
21 pages, 14 figures, 4 tables; accepted for publication in the Astronomical Journal