The GAPS programme at TNG. XLIII. A massive brown dwarf orbiting the active M dwarf TOI-5375

Maldonado, J.; Petralia, A.; Mantovan, G.; Rainer, M.; Lanza, A. F.; Di Maio, C.; Colombo, S.; Nardiello, D.; Benatti, S.; Borsato, L.; Carleo, I.; Desidera, S.; Micela, G.; Nascimbeni, V.; Malavolta, L.; Damasso, M.; Sozzetti, A.; Affer, L.; Biazzo, K.; Bignamini, A.; Bonomo, A. S.; Borsa, F.; Lund, M. B.; Mancini, L.; Molinari, E.; Molinaro, M.
Referencia bibliográfica

Astronomy and Astrophysics

Fecha de publicación:
6
2023
Número de autores
26
Número de autores del IAC
1
Número de citas
1
Número de citas referidas
1
Descripción
Context. Massive substellar companions orbiting active low-mass stars are rare. They, however, offer an excellent opportunity to study the main mechanisms involved in the formation and evolution of substellar objects.
Aims: We aim to unravel the physical nature of the transit signal observed by the TESS space mission on the active M dwarf TOI-5375.
Methods: We analysed the available TESS photometric data as well as high-resolution (R ~ 115 000) HARPS-N spectra. We combined these data to characterise the star TOI-5375 and to disentangle signals related to stellar activity from the companion transit signal in the light-curve data. We ran a Markov chain Monte Carlo analysis to derive the orbital solution and applied state-of-the-art Gaussian process regression to deal with the stellar activity signal.
Results: We reveal the presence of a companion in the boundary between the brown dwarfs and the very-low-mass stars orbiting around the star TOI-5375. The best-fit model corresponds to a companion with an orbital period of 1.721564 ± 10−6 d, a mass of 77 ± 8 MJ, and a radius of 0.99 ± 0.16 RJ.
Conclusions: We derive a rotation period for the host star of 1.9692 ± 0.0004 d, and we conclude that the star is very close to synchronising its rotation with the orbital period of the companion.

Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain).