A simple model to describe intrinsic stellar noise for exoplanet detection around red giants

TL;DR

This paper introduces a new noise model for red giant stars that improves exoplanet detection capabilities by accounting for stellar granulation and oscillations, aiding current and future space missions.

Contribution

The paper presents a reformulated noise model for red giants that enhances understanding of stellar noise and detection thresholds for exoplanets around evolved stars.

Findings

Neptune-sized planets are detectable around low luminosity red giants.

The new noise model outperforms previous models for evolved stars.

It can predict stellar noise for K2 and TESS missions.

Abstract

In spite of the huge advances in exoplanet research provided by the NASA Kepler Mission, there remain only a small number of transit detections around evolved stars. Here we present a reformulation of the noise properties of red-giant stars, where the intrinsic stellar granulation, and the stellar oscillations described by asteroseismology play a key role. The new noise model is a significant improvement on the current Kepler results for evolved stars. Our noise model may be used to help understand planet detection thresholds for the ongoing K2 and upcoming TESS missions, and serve as a predictor of stellar noise for these missions. As an application of our noise model, we explore the minimum detectable planet radii for red giant stars, and find that Neptune sized planets should be detectable around low luminosity red giant branch stars.