The Impact of Stellar Oscillations on Doppler Velocity Planet Searches

TL;DR

Stellar oscillations introduce noise in Doppler velocity measurements, especially for giant stars and short observations, affecting planet detection accuracy and requiring consideration in observational strategies.

Contribution

This study quantifies the impact of stellar oscillations on Doppler planet searches and establishes a power law relationship with stellar properties and observation times.

Findings

Oscillation noise scales with luminosity-to-mass ratio and integration time.

Impact is smaller than stellar activity but significant for giants and short exposures.

Oscillation jitter should be included to improve Keplerian fit accuracy.

Abstract

We present a quantitative investigation of the effect of stellar oscillations on Doppler velocity planet searches. Using data from four asteroseismological observation campaigns, we find a power law relationship between the noise impact of these oscillations on Doppler velocities and both the luminosity-to-mass of the target stars, and observed integration times. Including the impact of oscillation jitter should improve the quality of Keplerian fits to Doppler velocity data. The scale of the effect these oscillations have on Doppler velocity measurements is smaller than that produced by stellar activity, but is most significant for giant and subgiant stars, and at short integration times (i.e. less than a few minutes). Such short observation times tend to be used only for very bright stars. However, since it is these very same stars that tend to be targeted for the highest precision observations, as planet searches probe to lower and lower planet masses, oscillation noise for these stars can be significant and needs to be accounted for in observing strategies.