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A. L. Young (CTIO/NOAO, Middlebury College), M. Messineo (Sterrewacht Leiden), R. D. Blum, N. S. van der Bliek (CTIO/NOAO)
We present medium resolution (cross-dispersed) near infrared spectra of 4 SiO masing AGB stars in the Inner Galaxy obtained with OSIRIS at the 4-m Blanco Telescope at Cerro Tololo Inter-American Observatory in July 2001. This project served as a pilot project for a program to obtain NIR spectra of a large sample of SiO masing AGB stars in the Inner Galaxy (Messineo et al. in preparation). In this paper we present the NIR spectra of a small subset of SiO masing AGB stars. The spectra show strong CO absorption, enabling a preliminary determination of the stellar temperature. Using NIR photometry, and correcting for extinction, we are able to infer absolute magnitudes and place our objects along stellar isochrones, permitting estimates of their ages and metallicities.
Messineo et al. (2002) carried out a survey of AGB stars in the Inner Galaxy at 86 GHz (the SiO maser emission line), with sources selected from the ISOGAL/DENIS and MSX catalogues. This study revealed two kinematically distinct populations in the Inner Galaxy: a nuclear ring with a high velocity dispersion over a narrow spread in Galactic longitude, and a more diffuse bulge population.
To gain more insight in the physical properties of these SiO masing AGB stars, we are studying the stellar atmospheres of a significant subset of this survey by means of medium resolution NIR spectra. The combination of kinematic and spectroscopic data of the large population of AGB stars in the Galactic center will reveal important characteristics and clues to the evolution of the Inner Galaxy.
The author(s) of this abstract have provided an email address for comments about the abstract: alyoung@middlebury.edu
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.