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Massive young stellar objects in the Galactic center. I. Spectroscopic identification from Spitzer infrared spectrograph observations

Title
Massive young stellar objects in the Galactic center. I. Spectroscopic identification from Spitzer infrared spectrograph observations
Authors
An D.Ramirez S.V.Sellgren K.Arendt R.G.Boogert A.C.A.Robitaille T.P.Schultheis M.Cotera A.S.Smith H.A.Stolovy S.R.
Ewha Authors
안덕근
SCOPUS Author ID
안덕근scopus
Issue Date
2011
Journal Title
Astrophysical Journal
ISSN
0004-637XJCR Link
Citation
vol. 736, no. 2
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in the Galactic center (GC). Our sample of 107 YSO candidates was selected based on Infrared Array Camera (IRAC) colors from the high spatial resolution, high sensitivity Spitzer/IRAC images in the Central Molecular Zone, which spans the central ∼300pc region of the Milky Way. We obtained IRS spectra over 5-35 μm using both high- and low-resolution IRS modules. We spectroscopically identify massive YSOs by the presence of a 15.4 μm shoulder on the absorption profile of 15 μm CO 2 ice, suggestive of CO 2 ice mixed with CH 3OH ice on grains. This 15.4 μm shoulder is clearly observed in 16 sources and possibly observed in an additional 19 sources. We show that nine massive YSOs also reveal molecular gas-phase absorption from CO 2, C 2H 2, and/or HCN, which traces warm and dense gas in YSOs. Our results provide the first spectroscopic census of the massive YSO population in the GC. We fit YSO models to the observed spectral energy distributions and find YSO masses of 8-23 M ⊙, which generally agree with the masses derived from observed radio continuum emission. We find that about 50% of photometrically identified YSOs are confirmed with our spectroscopic study. This implies a preliminary star formation rate of ∼0.07 M ⊙ yr -1 at the GC. © 2011. The American Astronomical Society. All rights reserved.
DOI
10.1088/0004-637X/736/2/133
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사범대학 > 과학교육과 > Journal papers
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