Red giant seismology: observations

TL;DR

The paper discusses how CoRoT and Kepler data have revolutionized red giant seismology by revealing detailed oscillation patterns that enable precise interior structure analysis, including core probing and rotation measurement.

Contribution

It presents new insights into red giant interior structures through detailed seismic pattern analysis enabled by space-based observations.

Findings

Precise estimates of stellar mass and radius from seismic data

Clear differentiation between clump and RGB stars

Direct probing of stellar cores via mixed-mode analysis

Abstract

The CoRoT and Kepler missions provide us with thousands of red-giant light curves that allow a very precise asteroseismic study of these objects. Before CoRoT and Kepler, the red-giant oscillation patterns remained obscure. Now, these spectra are much more clear and unveil many crucial interior structure properties. For thousands of red giants, we can derive from the seismic data precise estimates of the stellar mass and radius, the evolutionary status of the giants (with a clear difference between clump and RGB stars), the internal differential rotation, the mass loss, the distance of the stars... Analysing this mass of information is made easy by the identification of the largely homologous red-giant oscillation patterns. For the first time, both pressure and mixed mode oscillation patterns can be precisely depicted. The mixed-mode analysis allows us, for instance, to probe directly the stellar core. Fine details completing the red-giant oscillation pattern then provide further information for a more detailed view on the interior structure, including differential rotation.