Amplitudes and lifetimes of solar-like oscillations observed by CoRoT* Red-giant versus main-sequence stars

TL;DR

This study analyzes and compares the amplitudes and lifetimes of solar-like oscillations in red giants and main-sequence stars observed by CoRoT, revealing different trends and proposing a unified scaling law with potential regimes.

Contribution

It provides a comprehensive analysis of oscillation parameters in red giants and main-sequence stars, introducing a new scaling law for mode amplitudes based on luminosity-to-mass ratio.

Findings

Red giants have high amplitudes and small widths in oscillations.

Widths vary differently with temperature in main-sequence stars versus red giants.

A single scaling law for amplitudes versus luminosity-to-mass ratio is proposed.

Abstract

Context. The advent of space-borne missions such as CoRoT or Kepler providing photometric data has brought new possibilities for asteroseismology across the H-R diagram. Solar-like oscillations are now observed in many stars, including red giants and main- sequence stars. Aims. Based on several hundred identified pulsating red giants, we aim to characterize their oscillation amplitudes and widths. These observables are compared with those of main-sequence stars in order to test trends and scaling laws for these parameters for both main-sequence stars and red giants. Methods. An automated fitting procedure is used to analyze several hundred Fourier spectra. For each star, a modeled spectrum is fitted to the observed oscillation spectrum, and mode parameters are derived. Results. Amplitudes and widths of red-giant solar-like oscillations are estimated for several hundred modes of oscillation. Amplitudes are relatively high (several hundred ppm) and widths relatively small (very few tenths of a {\mu}Hz). Conclusions. Widths measured in main-sequence stars show a different variation with the effective temperature than red giants. A single scaling law is derived for mode amplitudes of both red giants and main-sequence stars versus their luminosity to mass ratio. However, our results suggest that two regimes may also be compatible with the observations.