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Title: On the origin of the B-stars in the galactic center

We present a new directly observable statistic that uses sky position (x, y) and proper motion (v{sub x} , v{sub y} ) of stars near the massive black hole in the Galactic center to identify populations with high orbital eccentricities. It is most useful for stars with large orbital periods for which dynamical accelerations are difficult to determine. We apply this statistic to a data set of B-stars with a projected radii 0.''1 < p < 25'' (∼0.004-1 pc) from the massive black hole in the Galactic center. We compare the results with those from N-body simulations to distinguish between scenarios for their formation. We find that the scenarios favored by the data correlate strongly with particular K-magnitude intervals, corresponding to different zero-age, main-sequence (MS) masses and lifetimes. Stars with 14 ≲ m{sub K} ≲ 15 (15-20 M {sub ☉}, t {sub MS} = 8-13 Myr) match a disk formation origin well, whereas those with m{sub K} ≥ 15 (<15 M {sub ☉}, t {sub MS} > 13 Myr), if isotropically distributed, form a population that is more eccentric than thermal, which suggests a Hills binary-disruption origin.
Authors:
 [1] ; ; ;  [2] ;  [3] ;  [4]
  1. Astronomy Department and Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States)
  2. Max-Planck Institut für Extraterrestrische Physik, D-85748 Garching (Germany)
  3. Leiden Observatory, Leiden University, P.O. Box 9513, NL-2300 RA Leiden (Netherlands)
  4. Physics Department, Technion - Israel Institute of Technology, Haifa, Israel 32000 (Israel)
Publication Date:
OSTI Identifier:
22351526
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 784; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; BINARY STARS; BLACK HOLES; COMPARATIVE EVALUATIONS; GALAXIES; GALAXY NUCLEI; LIFETIME; MASS; PROPER MOTION; SIMULATION; SKY; STARS