First Spectroscopic Identification of Massive Young Stellar Objects, in the Galactic Center

Deokkeun An(1), Solange V. Ramírez(1), Kris Sellgren(2), Richard G. Arendt(3,4), A. C. Adwin Boogert(1), Mathias Schultheis(5,6), Susan R. Stolovy(7), Angela S. Cotera(8), Thomas P. Robitaille(9,10), and Howard A. Smith(9)

(1) Infrared Processing and Analysis Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125
(2) Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210
(3) CRESST/UMBC/GSFC, Code 665, NASA/Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771
(4) Science Systems and Applications, Inc.
(5) Observatoire de Besan\ccon, 41bis, avenue de l'Observatoire, F-25000 Besan\ccon, France
(6) Institut d'Astrophysique de Paris, CNRS, 98bis Bd Arago, F-75014 Paris, France
(7) Spitzer Science Center, California Institute of Technology, Mail Code 220-6, 1200 East California Boulevard, Pasadena, CA 91125
(8) SETI Institute, 515 North Whisman Road, Mountain View, CA 94043
(9) Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138
(10) Spitzer Postdoctoral Fellow

Paper: ApJL, 2009, in press

EPrint Server: 0907.4752

Abstract:

We report the detection of several molecular gas-phase and ice absorption features in three photometrically-selected young stellar object (YSO) candidates in the central 280 pc of the Milky Way. Our spectra, obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, reveal gas-phase absorption from CO₂ (15.0 micron ), C₂H₂ (13.7 micron ) and HCN (14.0 micron ). We attribute this absorption to warm, dense gas in massive YSOs. We also detect strong and broad 15 micron CO₂ ice absorption features, with a remarkable double-peaked structure. The prominent long-wavelength peak is due to CH₃OH-rich ice grains, and is similar to those found in other known massive YSOs. Our IRS observations demonstrate the youth of these objects, and provide the first spectroscopic identification of massive YSOs in the Galactic Center.

Preprints available from the authors at deokkeun@ipac.caltech.edu , or the raw TeX (no figures) if you click here.

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