A super-Earth and sub-Neptune transiting the late-type M dwarf LP 791-18
Abstract
Planets occur most frequently around cool dwarfs, but only a handful of specific examples are known to orbit the latest-type M stars. Using TESS photometry, we report the discovery of two planets transiting the low-mass star called LP 791-18 (identified by TESS as TOI 736). This star has spectral type M6V, effective temperature 2960 K, and radius 0.17 R_Sun, making it the third-coolest star known to host planets. The two planets straddle the radius gap seen for smaller exoplanets; they include a 1.1 R_Earth planet on a 0.95 day orbit and a 2.3 R_Earth planet on a 5 day orbit. Because the host star is small the loss of light during these planets' transits is fairly large (0.4% and 1.7%). This has allowed us to detect both planets' transits from ground-based photometry, refining their radii and orbital ephemerides. In the future, radial velocity observations and transmission spectroscopy can both probe these planets' bulk interior and atmospheric compositions, and additional photometric monitoring would be sensitive to even smaller transiting planets.
Keywords
Cite
@article{arxiv.1906.09267,
title = {A super-Earth and sub-Neptune transiting the late-type M dwarf LP 791-18},
author = {Ian J. M. Crossfield and William Waalkes and Elisabeth R. Newton and Norio Narita and Philip Muirhead and Kristo Ment and Elisabeth Matthews and Adam Kraus and Veselin Kostov and Molly R. Kosiarek and Stephen R. Kane and Howard Isaacson and Sam Halverson and Erica Gonzales and Mark Everett and Diana Dragomir and Karen A. Collins and Ashley Chontos and David Berardo and Jennifer G. Winters and Joshua N. Winn and Nicholas J. Scott and Barbara Rojas-Ayala and Aaron C. Rizzuto and Erik A. Petigura and Merrin Peterson and Teo Mocnik and Thomas Mikal-Evans and Nicholas Mehrle and Rachel Matson and Masayuki Kuzuhara and Jonathan Irwin and Daniel Huber and Chelsea Huang and Steve Howell and Andrew W. Howard and Teruyuki Hirano and Benjamin J. Fulton and Trent Dupuy and Courtney D. Dressing and Paul A. Dalba and David Charbonneau and Jennifer Burt and Zachory Berta-Thompson and Björn Benneke and Noriharu Watanabe and Joseph D. Twicken and Motohide Tamura and Joshua Schlieder and S. Seager and Mark E. Rose and George Ricker and Elisa Quintana and Sébastien Lépine and David W. Latham and Takayuki Kotani and Jon M. Jenkins and Yasunori Hori and Knicole Colon and Douglas A. Caldwell},
journal= {arXiv preprint arXiv:1906.09267},
year = {2019}
}
Comments
20 pages, 7 figures, 2 tables, 2 planets, 1 cool star. Submitted to AAS Journals