Giant planets population around B stars from the first part of the BEAST survey

• Main Authors: Delorme, P, Chomez, A, Squicciarini, V, Janson, M, Flasseur, O, Schib, O, Gratton, R, Lagrange, A-M, Langlois, M, Mayer, L, Helled, R, Reïffert, S, Kiefer, F, Biller, B, Chauvin, G, Fontanive, C, Henning, Th, Kenworthy, M, Marleau, G-D, Mesa, D, Meyer, M. R, Mordasini, C, Ringqvist, S. C, Samland, M, Vigan, A, Viswanath, G
• Format: Journal Article
• Language: English
• Published: 27-09-2024
• Subjects: Physics - Earth and Planetary Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.2409.18793

Exoplanets form from circumstellar protoplanetary discs whose fundamental
properties (notably their extent, composition, mass, temperature and lifetime)
depend on the host star properties, such as their mass and luminosity. B-stars
are among the most massive stars and their protoplanetary discs test extreme
conditions for exoplanet formation. This paper investigates the frequency of
giant planet companions around young B-stars (median age of 16 Myr) in the
Scorpius-Centaurus association, the closest association containing a large
population of B-stars. We systematically search for massive exoplanets with the
high-contrast direct imaging instrument SPHERE using the data from the BEAST
survey, that targets an homogeneous sample of young B-stars from the wide
Sco-Cen association. We derive accurate detection limits in case of
non-detections. We found evidence in previous papers for two substellar
companions around 42 stars. The masses of these companions are straddling the
~13 Jupiter mass deuterium burning limit but their mass ratio with respect to
their host star is close to that of Jupiter. We derive a frequency of such
massive planetary mass companions around B stars of 11-5+7%, accounting for the
survey sensitivity. The discoveries of substellar companions bcen b and mu2sco
B happened after only few stars in the survey had been observed, raising the
possibility that massive Jovian planets might be common around B-stars. However
our statistical analysis show that the occurrence rate of such planets is
similar around B-stars and around solar-type stars of similar age, while B-star
companions exhibit low mass ratios and larger semi-major axis.