Planets Around Massive Subgiants

TL;DR

This study investigates the occurrence and properties of planets around massive subgiant stars, revealing a scarcity of close-in planets around stars over 1.5 solar masses and a trend of increasing giant planet frequency with stellar mass.

Contribution

It demonstrates that subgiants are effective proxies for studying planets around massive stars and presents early results indicating a correlation between stellar mass and planet occurrence.

Findings

Fewer planets within 1 AU around stars >1.5 Msun

Evidence of increased giant planet occurrence with stellar mass

Subgiants serve as useful proxies for massive star planet searches

Abstract

Compared to planets around Sun-like stars, relatively little is known about the occurrence rate and orbital properties of planets around stars more massive than 1.3 Msun. The apparent deficit of planets around massive stars is due to a strong selection bias against early-type dwarfs in Doppler-based planet searches. One method to circumvent the difficulties inherent to massive main-sequence stars is to instead observe them after they have evolved onto the subgiant branch. We show how the cooler atmospheres and slower rotation velocities of subgiants make them ideal proxies for F- and A-type stars. We present the early results from our planet search that reveal a paucity of planets orbiting within 1 AU of stars more massive than 1.5 Msun, and evidence of a rising trend in giant planet occurrence with stellar mass.