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+0.16 R⊕ ). 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.
Original language | English |
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Article number | 167 |
Number of pages | 17 |
Journal | Astronomical Journal |
Volume | 165 |
Issue number | 4 |
Early online date | 20 Mar 2023 |
DOIs | |
Publication status | Published - 1 Apr 2023 |
Bibliographical note
Funding Information:R.C. is supported by the Banting Postdoctoral Fellowship Program administered by the Government of Canada.
This material is based upon work supported by the National Aeronautics and Space Administration under grants 80NSSC22K0166 and 80NSSC22K0296 in support of the TESS Guest Investigator Program.
This work has made use of data from the European Space Agency (ESA) mission Gaia ( https://www.cosmos.esa.int/gaia ), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium ). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA’s Science Mission Directorate.
This work makes use of observations from the LCOGT network. Part of the LCOGT telescope time was granted by NOIRLab through the Mid-Scale Innovations Program (MSIP). MSIP is funded by the NSF.
Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science