Oscillation mode linewidths of main-sequence and subgiant stars observed by Kepler

TL;DR

This study analyzes Kepler data to understand how the linewidths of solar-like oscillation modes vary with effective temperature in main-sequence and subgiant stars, revealing a specific scaling relation.

Contribution

It presents the first detailed scaling relation between mode linewidths and effective temperature for cool main-sequence and subgiant stars using Bayesian and maximum likelihood methods.

Findings

Mode linewidths follow a power-law relation with effective temperature.

The power-law index is approximately 13 for linewidths at maximum mode height.

The relation is valid only within the temperature range of the studied stars.

Abstract

Solar-like oscillations have been observed by {{\it Kepler}} and CoRoT in several solar-type stars. We study the variations of stellar p-mode linewidth as a function of effective temperature. Time series of 9 months of Kepler data have been used. The power spectra of 42 cool main-sequence stars and subgiants have been analysed using both Maximum Likelihood Estimators and Bayesian estimators, providing individual mode characteristics such as frequencies, linewidths and mode heights. Here we report on the mode linewidth at maximum power and at maximum mode height for these 42 stars as a function of effective temperature. We show that the mode linewidth at either maximum mode height or maximum amplitude follows a scaling relation with effective temperature, which is a combination of a power law plus a lower bound. The typical power law index is about 13 for the linewidth derived from the maximum mode height, and about 16 for the linewidth derived from the maximum amplitude while the lower bound is about 0.3 microHz and 0.7 microHz, respectively. We stress that this scaling relation is only valid for the cool main-sequence stars and subgiants, and does not have predictive power outside the temperature range of these stars.