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Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?

Bluhm, P; Luque, R; Espinoza, N; Palle, E; Caballero, JA; Dreizler, S; Livingston, JH; ... Zohrabi, F; + view all (2020) Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap? Astronomy & Astrophysics , 639 , Article A132. 10.1051/0004-6361/202038160. Green open access

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Abstract

We report the confirmation of a transiting planet around the bright weakly active M0.5 V star TOI-1235 (TYC 4384–1735–1, V ≈ 11.5 mag), whose transit signal was detected in the photometric time series of sectors 14, 20, and 21 of the TESS space mission. We confirm the planetary nature of the transit signal, which has a period of 3.44 d, by using precise RV measurements with the CARMENES, HARPS-N, and iSHELL spectrographs, supplemented by high-resolution imaging and ground-based photometry. A comparison of the properties derived for TOI-1235 b with theoretical models reveals that the planet has a rocky composition, with a bulk density slightly higher than that of Earth. In particular, we measure a mass of M_{p} = 5.9 ± 0.6 M_{⊕} and a radius of R_{p} = 1.69 ± 0.08 R_{⊕}, which together result in a density of ρp = 6.7\tfrac{+1.3}{-1.1}g cm^{−3}. When compared with other well-characterized exoplanetary systems, the particular combination of planetary radius and mass places our discovery in the radius gap, which is a transition region between rocky planets and planets with significant atmospheric envelopes. A few examples of planets occupying the radius gap are known to date. While the exact location of the radius gap for M dwarfs is still a matter of debate, our results constrain it to be located at around 1.7 R_{⊕} or larger at the insolation levels received by TOI-1235 b (~60 S_{⊕}). This makes it an extremely interesting object for further studies of planet formation and atmospheric evolution.

Type: Article
Title: Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?
Open access status: An open access version is available from UCL Discovery
DOI: 10.1051/0004-6361/202038160
Publisher version: https://doi.org/10.1051/0004-6361/202038160
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher's terms and conditions.
Keywords: techniques: photometric, techniques: radial velocities, stars: individual: TOI-1235, stars: late-type
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10105282
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