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Orbits and origins of the young stars in the central parsec of the galaxy

Lu, J. R. and Ghez, A. M. and Morris, M. and Hornstein, S. D. and Matthews, K. (2008) Orbits and origins of the young stars in the central parsec of the galaxy. Journal of Physics: Conference Series, 131 (1). Art. No. 012012. ISSN 1742-6596. doi:10.1088/1742-6596/131/1/012012.

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We present new proper motions from the 10 m Keck telescopes for a puzzling population of massive, young stars located within a parsec of the supermassive black hole at the Galactic Center. Our proper motion measurements have uncertainties of only 0.07 mas yr^(−1) (3 km s^(−1) ), which is ≳7 times better than previous proper motion measurements for these stars, and enables us to measure accelerations as low as 0.2 mas yr^(−2) (7 km s^(−1) yr^(−1) ). These measurements, along with stellar line-of-sight velocities from the literature, constrain the true orbit of each individual star and allow us to directly test the hypothesis that the massive stars reside in two stellar disks as has been previously proposed. Analysis of the stellar orbits reveals only one disk of young stars using a method that is capable of detecting disks containing at least 7 stars. The detected disk contains 50% (38 of 73) of the young stars, is inclined by ~115° from the plane of the sky, and is oriented at a position angle of ∼100° East of North. The on-disk and off-disk populations have similar K-band luminosity functions and radial distributions that decrease at larger radii as ∝ r^(−2). The disk has an out-of-the-disk velocity dispersion of 28±6 km s^(−1) , which corresponds to a half-opening angle of 7°±2° , and several candidate disk members have eccentricities greater than 0.2. Our findings suggest that the young stars may have formed in situ but in a more complex geometry than a simple thin circular disk.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lu, J. R.0000-0001-9611-0009
Ghez, A. M.0000-0003-3230-5055
Morris, M.0000-0002-6753-2066
Additional Information:© 2008 IOP Publishing Ltd Support for this work was provided by J.R.L.’s NSF Graduate Research Fellowship, NSF grant AST-0406816, and the NSF Science & Technology Center for AO, managed by UCSC (AST- 9876783). The W.M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Experimental/ black holes; Galactic centre; stellar motion/ stellar orbits; young stars; Keck telescope observations; supermassive black hole; Galactic Center; proper motion measurements; stellar line-of-sight velocities; stellar disks; Galaxy/ A9850L The Galaxy; A9850E Galactic structure, content and morphology; A9710W Stellar space motions (proper motions, radial velocities, and orbits); A9580G Infrared astronomical observations/ Galaxy
Issue or Number:1
Record Number:CaltechAUTHORS:LUJjpcs08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13353
Deposited By: Arun Sannuti
Deposited On:11 Feb 2009 00:41
Last Modified:12 Jul 2022 19:52

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