11 Jun 2025: Heather Johnston

Speaker: Heather Johnston (Exeter)

Date: Wednesday 11 June 2025

Time: 15:00

Location: Physics 3.21

The rise and fall of the giant planet occurrence rate

Intermediate-mass stars are (i) most likely to host a giant planet; (ii) host gas-rich debris discs; and (iii) evolve differently from their low-mass counterparts. I will explore planet formation around these intermediate-mass stars and the role of pre-main sequence stellar evolution. I present the results of our planet population synthesis in which we model the rise and fall of the RV giant planet occurrence rate as a function of stellar mass and metallicity. Our results show that the accretion rate is a key mechanism that governs the occurrence rate distribution. We find that giant planets around more massive stars tend to be (i) more massive, (ii) form at a faster rate, and (iii) undergo runaway gas accretion at different locations than around low-mass stars. Hence, we can infer that giant planet composition may vary with stellar mass.