Galactic bulge giants: probing stellar and galactic evolution I. Catalogue of Spitzer IRAC and MIPS sources

TL;DR

This study uses sensitive Spitzer infrared observations to catalog Galactic bulge stars, aiming to understand stellar mass-loss processes and evolution by analyzing their luminosities and infrared properties.

Contribution

It provides a comprehensive, high-quality infrared catalog of bulge stars, enabling detailed analysis of stellar evolution and mass-loss onset in the Galactic bulge.

Findings

Good agreement with previous surveys and models

High sensitivity reveals detailed stellar properties

Supports theories of late stellar evolution

Abstract

Aims: We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous infrared surveys of the bulge has been rather limited, thus fundamental questions for late stellar evolution, such as the stage at which substantial mass-loss begins on the red giant branch and its dependence on fundamental stellar properties, remain unanswered. We aim at providing evidence and answers to these questions. Methods: To this end, we observed seven 15 times 15 arcmin^2 fields in the nuclear bulge and its vicinity with unprecedented sensitivity using the IRAC and MIPS imaging instruments on-board the Spitzer Space Telescope. In each of the fields, tens of thousands of point sources were detected. Results: In the first paper based on this data set, we present the observations, data reduction, the final catalogue of sources, and a detailed comparison to previous mid-IR surveys of the Galactic bulge, as well as to theoretical isochrones. We find in general good agreement with other surveys and the isochrones, supporting the high quality of our catalogue.