Spitzer/IRAC Characterization of Galactic AGB Stars

TL;DR

This paper presents initial results from a Spitzer IRAC survey aimed at characterizing the infrared colors of AGB stars to improve their identification in galactic and extragalactic surveys.

Contribution

It provides the first characterization of IRAC colors of AGB stars, offering template magnitudes and colors to aid future infrared surveys.

Findings

IRAC colors of AGB stars are influenced by molecular absorption features.

The study offers a set of template magnitudes and colors for AGB stars.

Results facilitate better identification of AGB stars in infrared surveys.

Abstract

The Spitzer Space Telescope and in particular its InfraRed Array Camera (IRAC) is an ideal facility to study the distribution of AGB stars in our own and other galaxies because of its efficiency in surveying vast areas of the sky and its ability to detect sources with infrared excess. The IRAC colors of AGB stars, however, are not well known because cool stars have numerous molecular absorption features in the spectral region covered by the IRAC photometric system. The presence and strength of these features depends on the chemistry of the stellar atmosphere and the mass loss rate and can change with time due to the star's variability. To characterize the IRAC colors of AGB stars, we are carrying out a Spitzer Guaranteed Time Observation program to observe a sample of AGB stars with IRAC. The results will be made available to the community in the form of template magnitudes and colors for each target with the goal of aiding the identification of AGB stars in already available and future IRAC surveys. We present here the first results of this project.