Testing Scaling Relations for Solar-Like Oscillations from the Main Sequence to Red Giants using Kepler Data

TL;DR

This study tests and refines asteroseismic scaling relations across a wide range of stellar types using Kepler data, revealing the need for revised models to accurately predict oscillation amplitudes and exploring stellar activity effects.

Contribution

It introduces a revised amplitude scaling relation with separate luminosity-mass dependence and investigates the impact of stellar activity on oscillation amplitudes.

Findings

Revised amplitude scaling relation achieves ~25% precision across stellar types.

Difference in Delta_nu-nu_max relation explained by temperature and mass distributions.

Evidence of amplitude suppression linked to stellar activity, especially in subgiants.

Abstract

We have analyzed solar-like oscillations in ~1700 stars observed by the Kepler Mission, spanning from the main-sequence to the red clump. Using evolutionary models, we test asteroseismic scaling relations for the frequency of maximum power (nu_max), the large frequency separation (Delta_nu) and oscillation amplitudes. We show that the difference of the Delta_nu-nu_max relation for unevolved and evolved stars can be explained by different distributions in effective temperature and stellar mass, in agreement with what is expected from scaling relations. For oscillation amplitudes, we show that neither (L/M)^s scaling nor the revised scaling relation by Kjeldsen & Bedding (2011) are accurate for red-giant stars, and demonstrate that a revised scaling relation with a separate luminosity-mass dependence can be used to calculate amplitudes from the main-sequence to red-giants to a precision of ~25%. The residuals show an offset particularly for unevolved stars, suggesting that an additional physical dependency is necessary to fully reproduce the observed amplitudes. We investigate correlations between amplitudes and stellar activity, and find evidence that the effect of amplitude suppression is most pronounced for subgiant stars. Finally, we test the location of the cool edge of the instability strip in the Hertzsprung-Russell diagram using solar-like oscillations and find the detections in the hottest stars compatible with a domain of hybrid stochastically excited and opacity driven pulsation.