2 micron spectroscopy within 0".13 of Sagittarius A

被引:33
作者
Figer, DF
Becklin, EE
McLean, IS
Gilbert, AM
Graham, JR
Larkin, JE
Levenson, NA
Teplitz, HI
Wilcox, MK
Morris, M
机构
[1] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[2] Univ Calif Los Angeles, Dept Phys & Astron, Div Astron & Astrophys, Los Angeles, CA 90095 USA
[3] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[4] Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA
[5] NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA
基金
美国国家科学基金会;
关键词
galaxy : center; infrared : stars; ISM : individual (Sagittarius A*); stars : formation; techniques : spectroscopic;
D O I
10.1086/312596
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present moderate- (R approximate to 2700) and high-resolution (R approximate to 22,400) 2.0-2.4 mu m spectroscopy of the central 0.1 arcsec(2) of the Galaxy obtained with the facility near-infrared spectrometer (NIRSPEC) for the Keek II telescope. The composite spectra do not have any features attributable to the brightest stars in the central cluster; i.e., after background subtraction, W12CO(2-0) < 2 Angstrom. This Stringent limit leads us to conclude that the majority, if not all, of the stars are hotter than typical red giants. Coupled with previously reported photometry, we conclude that the sources are likely OB main-sequence stars. In addition, the continuum slope in the composite spectrum is bluer than that of a red giant and is similar to that of the nearby hot star IRS 16NW. It is unlikely that they are late-type giants stripped of their outer envelopes because such sources would be much fainter than those observed. Given their inferred youth (tau(age) < 20 Myr), we suggest the possibility that the stars have formed within 0.1 pc of the supermassive black hole. We find a newly identified broad-line component (V-FWHM approximate to 1000 km s(-1)) toward the 2.2178 mu m [Fe III] line located within a few arcseconds of Sagittarius AX. A similar component is not seen in the Br gamma emission.
引用
收藏
页码:L49 / L52
页数:4
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