A bimodal companion mass distribution for B-type hosts: hints from the SHINE and BEAST surveys
ABSTRACT
Radial velocity and direct imaging studies have shown that the occurrence of giant planets increases with stellar mass, at least up to 1.7 M_sun. In order to understand whether the trend continues for more massive hosts, the direct imaging B-star Exoplanet Abundance Study (BEAST) was initiated to look for giant planets around B-type (2.4 ≲ M/M_sun ≲ 15) members of the young Scorpius-Centaurus association (5-30 Myr). While the survey is ongoing, two ~15 M_J companions to massive (6-10 M_sun) stars have been detected; it is still not clear whether they constitute the high-mass tail of a planetary population, or the low-mass end of a stellar population. In this talk, I will compare the mass and separation distributions of stellar+substellar companions detected in the ongoing BEAST and SHINE surveys, spanning a large range of stellar masses (0.7 ≲ M/M_sun ≲ 15). The two companions are most likely associated to a planet-like population; in addition to this, I will illustrate how the overall companion mass distribution is significantly different from the IMF, showing a bimodality with a hiatus corresponding to the brown dwarf desert already observed in radial velocity studies at lower separations. Completion of the two surveys will clarify the significance of these preliminary results, paving the way to the understanding of planet formation processes around high-mass stars.
The seminar will be in Aula Jappelli and on line:
with google meet: iue-vhhd-hur
INAF/OAPD
