Impact of rotation on the amplitude of acoustic modes in solar-like stars: Insights from hydrodynamical simulations

TL;DR

This study uses hydrodynamical simulations to show that increasing stellar rotation decreases acoustic mode amplitudes and increases damping, explaining the lower detectability of oscillations in rapidly rotating solar-like stars.

Contribution

First systematic simulation-based investigation demonstrating how stellar rotation suppresses acoustic mode amplitudes and enhances damping in solar-like stars.

Findings

Acoustic mode amplitudes decline with increasing rotation rate.

Mode damping rates increase as rotation rate rises.

Results explain the reduced asteroseismic detectability in fast rotators.

Abstract

In solar-like stars, acoustic modes provide the main way of probing their internal structure and dynamics. Although these modes are expected to be ubiquitous in stars with convective envelopes, Kepler observations reveal that a significant fraction of solar-like stars show no detectable acoustic modes, particularly among rapidly rotating and magnetically active stars. Recent theoretical work has proposed that rotation tends to inhibit convective motions, thereby reducing the power available for stochastic excitation of low degree acoustic modes. Here, we test this prediction using fully compressible hydrodynamical simulations of a solar-like star. We perform a series of 2.5D simulations, which consider longitudinal symmetry, using the MUSIC code spanning rotation rates from 0 to 8 $\Omega_{\odot}$. We find a clear and systematic decline of acoustic mode amplitudes with increasing rotation rate. In the most rapidly rotating models, mode damping rates are also enhanced. The combined reduction in excitation and increase in damping with increasing rotation rate provide a physical explanation for the observed decrease in mode detectability in rapidly rotating solar-like stars. Our results demonstrate that rotation can significantly modify oscillation properties and must be accounted for when interpreting asteroseismic observations.