Amplitudes of solar-like oscillations: a new scaling relation

TL;DR

This paper introduces a new scaling relation for solar-like oscillation amplitudes based on granulation power, improving predictions especially for F-type stars, and extends applicability to red giants.

Contribution

A novel scaling relation for oscillation amplitudes that incorporates damping effects and is grounded in granulation power scaling, enhancing predictive accuracy.

Findings

The new relation better matches observed amplitudes in F-type stars.

It includes a dependence on mode lifetime for improved accuracy.

Scaling relations are proposed for granulation background properties.

Abstract

Solar-like oscillations are excited by near-surface convection and are being observed in growing numbers of stars using ground and space-based telescopes. We have previously suggested an empirical scaling relation to predict their amplitudes (Kjeldsen and Bedding 1995). This relation has found widespread use but it predicts amplitudes in F-type stars that are higher than observed. Here we present a new scaling relation that is based on the postulate that the power in velocity fluctuations due to p-mode oscillations scales with stellar parameters in the same way as the power in velocity fluctuations due to granulation. The new relation includes a dependence on the damping rate via the mode lifetime and should be testable using observations from the CoRoT and Kepler missions. We also suggest scaling relations for the properties of the background power due to granulation and argue that both these and the amplitude relations should be applicable to red giant stars.