The Pan-Pacific Planet Search: A southern hemisphere search for planets orbiting evolved massive stars

TL;DR

The Pan-Pacific Planet Search investigates planets around evolved massive stars, aiming to fill observational gaps and improve understanding of planet formation around higher-mass stars.

Contribution

This survey provides new high-precision Doppler velocity data for 170 subgiant stars, addressing observational biases and expanding knowledge of planetary systems around massive stars.

Findings

Monitoring nearly all bright subgiants in the sample

Complementing northern hemisphere surveys for comprehensive data

Aims to determine planet occurrence rates around higher-mass stars

Abstract

The vast majority of known extrasolar planets orbit stars with a narrow range of masses (0.7-1.3 M_sun). Recent years have seen rapid growth in our knowledge about the properties of planetary systems with host stars significantly more massive than the Sun. Planet formation models predict that giant planets are more common around higher-mass stars (M>1.5M_sun). However, these types of stars pose severe observational challenges while on the main sequence, resulting in a strong bias against them in current planet searches. Fortunately, it is possible to obtain high-precision Doppler velocities for these massive stars as they evolve off the main sequence and cool as subgiants. We describe the Pan-Pacific Planet Search, a survey of 170 subgiant stars using the 3.9m Australian Astronomical Telescope. In collaboration with J. Johnson's Keck survey of Northern retired A stars, we are monitoring nearly every subgiant brighter than V=8. This survey will provide critical statistics on the frequency and characteristics of planetary systems formed around higher-mass stars.