Volume 632, December 2019
|Number of page(s)||9|
|Section||Letters to the Editor|
|Published online||10 December 2019|
Letter to the Editor
Determining the mass of the planetary candidate HD 114762 b using Gaia
Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
Accepted: 13 November 2019
The first planetary candidate discovered by Latham et al. (1989, Nature, 339, 38) with radial velocities around a solar-like star other than the Sun, HD 114762 b, was detected with a minimum mass of 11 MJ. The small v sin i ∼ 0 km s−1 that is otherwise measured by spectral analysis indicated that this companion of a late-F subgiant star better corresponds to a massive brown dwarf (BD) or even a low-mass M-dwarf seen nearly face-on. To our knowledge, the nature of HD 114762 b is still undetermined. The astrometric noise measured for this system in the first data release, DR1, of the Gaia mission allows us to derive new constraints on the astrometric motion of HD 114762 and on the mass of its companion. We use the method GASTON, introduced in a preceding paper, which can simulate Gaia data and determine the distribution of inclinations that are compatible with the astrometric excess noise. With an inclination of 6.26.2+1.9−1.3 degree, the mass of the companion is constrained to Mb = 108+31−26 MJ. HD 114762 b thus indeed belongs to the M-dwarf domain, down to brown dwarfs, with Mb > 13.5 MJ at the 3σ level, and is not a planet.
Key words: stars: individual: HD 114762 / planetary systems / stars: low-mass / astrometry
© F. Kiefer 2019
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