Galactic bulge giants: probing stellar and galactic evolution^*

I. Catalogue of Spitzer IRAC and MIPS sources

¹ Instituut voor Sterrenkunde, K. U. Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium e-mail: stefan@ster.kuleuven.be
² Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
³ IASA and Section of Astrophysics, Astronomy and Mechanics, Department of Physics, University of Athens, Panepistimiopolis, 157 84 Zografos, Athens, Greece
⁴ Dipartimento di Fisica Generale “A. Avogadro”, Universita degli Studi di Torino, via Pietro Giuria 1, 10125 Torino, Italy
⁵ Observatoire de Besançon, 41bis avenue de l'Observatoire, 25000 Besançon, France
⁶ Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Rd., Hanscom AFB, MA 01731, USA
⁷ Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium

Received: 30 March 2009
Accepted: 15 January 2010

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 × 15 arcmin² 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.