TOI-1695 b : a water world orbiting an early-M dwarf in the planet radius valley
Abstract
Characterizing the bulk compositions of transiting exoplanets within the M dwarf radius valley offers a unique means to establish whether the radius valley emerges from an atmospheric mass-loss process or is imprinted by planet formation itself. We present the confirmation of such a planet orbiting an early-M dwarf (Tmag = 11.0294 ± 0.0074, Ms = 0.513 ± 0.012 M ⊙, Rs = 0.515 ± 0.015 R ⊙, and Teff = 3690 ± 50 K): TOI-1695 b (P = 3.13 days and Rp=1.90−0.14+0.16R⊕ ). TOI-1695 b’s radius and orbital period situate the planet between model predictions from thermally driven mass loss versus gas depleted formation, offering an important test case for radius valley emergence models around early-M dwarfs. We confirm the planetary nature of TOI-1695 b based on five sectors of TESS data and a suite of follow-up observations including 49 precise radial velocity measurements taken with the HARPS-N spectrograph. We measure a planetary mass of 6.36 ± 1.00 M ⊕, which reveals that TOI-1695 b is inconsistent with a purely terrestrial composition of iron and magnesium silicate, and instead is likely a water-rich planet. Our finding that TOI-1695 b is not terrestrial is inconsistent with the planetary system being sculpted by thermally driven mass loss. We present a statistical analysis of seven well-characterized planets within the M dwarf radius valley demonstrating that a thermally driven mass-loss scenario is unlikely to explain this population.
Citation
Cherubim , C , Cloutier , R , Charbonneau , D , Stockdale , C , Stassun , K G , Schwarz , R P , Safonov , B , Mortier , A , Lewin , P , Latham , D W , Horne , K , Haywood , R D , Gonzales , E , Goliguzova , M V , Collins , K A , Ciardi , D R , Bieryla , A , Belinski , A A , Wohler , B , Watson , C A , Vanderspek , R , Udry , S , Sozzetti , A , Ségransan , D , Sasselov , D , Ricker , G R , Rice , K , Poretti , E , Piotto , G , Pepe , F , Molinari , E , Micela , G , Mayor , M , Lovis , C , López-Morales , M , Jenkins , J M , Essack , Z , Dumusque , X , Doty , J P , Colón , K D , Cameron , A C & Buchhave , L A 2023 , ' TOI-1695 b : a water world orbiting an early-M dwarf in the planet radius valley ' , Astronomical Journal , vol. 165 , no. 4 , 167 . https://doi.org/10.3847/1538-3881/acbdfd
Publication
Astronomical Journal
Status
Peer reviewed
ISSN
0004-6256Type
Journal article
Rights
Copyright © 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Description
Funding: B.S.S. acknowledges the support of Ministry of Science and Higher Education of the Russian Federation under the grant 075-15-2020-780 (N13.1902.21.0039).Collections
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