Velocity dispersion and the stellar population in the central 1. 2 parsecs of the Galaxy

New observations of the 2.3 micron absorption band head of CO in integrated stellar light in the central 1.2 pc of the Galaxy are presented. These data confirm that the velocity dispersion of the stars increases toward the Galactic center and totally dominates their systematic rotation at small radi...

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Veröffentlicht in:The Astrophysical journal 1990-08, Vol.359
Hauptverfasser: Sellgren, K., Mcginn, M.T., Becklin, E.E., Hall, D.N.
Format: Artikel
Sprache:eng
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Zusammenfassung:New observations of the 2.3 micron absorption band head of CO in integrated stellar light in the central 1.2 pc of the Galaxy are presented. These data confirm that the velocity dispersion of the stars increases toward the Galactic center and totally dominates their systematic rotation at small radii. The velocity dispersion is constant an average value of 125 km/s within about 30 arcsec projected diameter central region. The strength of the CO features decreases in the integrated faint light within the same region. These observations are all consistent with the hypothesis that both the diffuse 2 micron light and the bright 2 micron point sources in the central region are dominated by sources that have little or no CO absorption feature. The observed CO feature at projected distances less than 0.6 pc thus actually arises in stars that are at true radii greater than 0.6 pc. The mass distribution at radius between 3.7 and 0.6 pc from IRS 16 is strong evidence for an increasing mass/2 micron radiation ratio toward the Galactic center. 24 refs.
ISSN:0004-637X
1538-4357
DOI:10.1086/169039