Asteroseismic classification of stellar populations among 13000 red giants observed by Kepler

TL;DR

This study uses asteroseismology to classify over 13,000 red giants observed by Kepler, revealing their evolutionary states, mass distributions, and rotational properties, thereby enhancing understanding of stellar populations and evolution.

Contribution

It introduces an automated method to extract frequencies and classify red giants into different populations based on their asteroseismic properties, expanding the scope of stellar population studies.

Findings

Classification of stars into red giant branch, red clump, and secondary clump.

Detection of rotationally induced frequency splittings in many stars.

Large sample provides insights into stellar evolution and Galactic structure.

Abstract

Of the more than 150000 targets followed by the Kepler Mission, about 10% were selected as red giants. Due to their high scientific value, in particular for Galaxy population studies and stellar structure and evolution, their Kepler light curves were made public in late 2011. More than 13000 (over 85%) of these stars show intrinsic flux variability caused by solar-like oscillations making them ideal for large scale asteroseismic investigations. We automatically extracted individual frequencies and measured the period spacings of the dipole modes in nearly every red giant. These measurements naturally classify the stars into various populations, such as the red giant branch, the low-mass (M/Msol < 1.8) helium-core-burning red clump, and the higher-mass (M/Msol > 1.8) secondary clump. The period spacings also reveal that a large fraction of the stars show rotationally induced frequency splittings. This sample of stars will undoubtedly provide an extremely valuable source for studying the stellar population in the direction of the Kepler field, in particular when combined with complementary spectroscopic surveys.