Probing the Deep End of the Milky Way with New Oscillating Kepler Giants

TL;DR

This paper identifies and characterizes a new, distant population of red giant stars in the Milky Way using Kepler data, expanding the reach of galactic archaeology.

Contribution

It reports the discovery of 850 red giants misclassified as dwarfs, enabling exploration of previously inaccessible regions of our Galaxy.

Findings

Detected oscillations in 850 red giants beyond 10 kpc

Revised stellar parameters for the new red giant sample

Distribution analysis of masses, distances, and evolutionary states

Abstract

The Kepler mission has been a success in both exoplanet search and stellar physics studies. Red giants have actually been quite a highlight in the Kepler scene. The Kepler long and almost continuous four-year observations allowed us to detect oscillations in more than 15,000 red giants targeted by the mission. However by looking at the power spectra of 45,000 stars classified as dwarfs according to the Q1-16 Kepler star properties catalog, we detected red-giant like oscillations in 850 stars. Even though this is a small addition to the known red-giant sample, these misclassified stars represent a goldmine for galactic archeology studies. Indeed they happen to be fainter (down to Kp~16) and more distant (d>10kpc) than the known red giants, opening the possibility to probe unknown regions of our Galaxy. The faintness of these red giants with detected oscillations is very promising for detecting acoustic modes in red giants observed with K2 and TESS. In this talk, I will present this new sample of red giants with their revised stellar parameters derived from asteroseismology. Then I will discuss about the distribution of their masses, distances, and evolutionary states compared to the previously known sample of red giants.