The SAGE-Spec Spitzer Legacy program: The life-cycle of dust and gas in the Large Magellanic Cloud

TL;DR

The SAGE-Spec program provides detailed infrared spectroscopic data of the Large Magellanic Cloud, revealing new insights into dust and gas life cycles, stellar evolution, and extragalactic features, enhancing classification and understanding of cosmic phenomena.

Contribution

It offers the first detection of an extragalactic '21 um' feature and clarifies the nature of disks around RV Tauri stars in the LMC, along with comprehensive data products for community use.

Findings

Detection of an extragalactic '21 um' feature.

Observation of ice features in young star spectra.

Serendipitous discovery of a background quasar.

Abstract

The SAGE-Spec Spitzer Legacy program is a spectroscopic follow-up to the SAGE-LMC photometric survey of the Large Magellanic Cloud carried out with the Spitzer Space Telescope. We present an overview of SAGE-Spec and some of its first results. The SAGE-Spec program aims to study the life cycle of gas and dust in the Large Magellanic Cloud, and to provide information essential to the classification of the point sources observed in the earlier SAGE-LMC photometric survey. We acquired 224.6 hours of observations using the InfraRed Spectrograph and the SED mode of the Multiband Imaging Photometer for Spitzer. The SAGE-Spec data, along with archival Spitzer spectroscopy of objects in the Large Magellanic Cloud, are reduced and delivered to the community. We discuss the observing strategy, the specific data reduction pipelines applied and the dissemination of data products to the scientific community. Initial science results include the first detection of an extragalactic "21 um" feature towards an evolved star and elucidation of the nature of disks around RV Tauri stars in the Large Magellanic Cloud. Towards some young stars, ice features are observed in absorption. We also serendipitously observed a background quasar, at a redshift of z~0.14, which appears to be host-less.