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Title: DETECTION OF GALACTIC CENTER SOURCE G2 AT 3.8 μm DURING PERIAPSE PASSAGE

We report new observations of the Galactic Center source G2 from the W. M. Keck Observatory. G2 is a dusty red object associated with gas that shows tidal interactions as it nears its closest approach with the Galaxy's central black hole. Our observations, conducted as G2 passed through periapse, were designed to test the proposal that G2 is a 3 Earth mass gas cloud. Such a cloud should be tidally disrupted during periapse passage. The data were obtained using the Keck II laser guide star adaptive optics system (LGSAO) and the facility near-infrared camera (NIRC2) through the K' [2.1 μm] and L' [3.8 μm] broadband filters. Several results emerge from these observations: (1) G2 has survived its closest approach to the black hole as a compact, unresolved source at L', (2) G2's L' brightness measurements are consistent with those over the last decade, (3) G2's motion continues to be consistent with a Keplerian model. These results rule out G2 as a pure gas cloud and imply that G2 has a central star. This star has a luminosity of ∼30 L {sub ☉} and is surrounded by a large (∼2.6 AU) optically thick dust shell. The differences between the L' and Br-γ observations canmore » be understood with a model in which L' and Br-γ emission arises primarily from internal and external heating, respectively. We suggest that G2 is a binary star merger product and will ultimately appear similar to the B-stars that are tightly clustered around the black hole (the so-called S-star cluster)« less
Authors:
; ; ; ; ; ; ; ; ;  [1] ; ;  [2] ;  [3] ;  [4] ; ;  [5] ;  [6]
  1. Department of Physics and Astronomy, University of California Los Angeles (UCLA), 465 Portola Plaza, Los Angeles, CA 90095 (United States)
  2. W. M. Keck Observatory, 65-1160 Mamalahoa Hwy., Kamuela, HI 96743 (United States)
  3. Department of Physics and Astronomy, University of California Riverside, 900 University Avenue, Riverside, CA 92521 (United States)
  4. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, M5S 3H4 ON (Canada)
  5. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  6. Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
22364518
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 796; 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; BINARY STARS; BLACK HOLES; BRIGHTNESS; CAMERAS; CLOUDS; COSMIC DUST; DETECTION; GALAXY NUCLEI; LUMINOSITY; MASS; MILKY WAY; OPTICS; RESOLUTION; STAR CLUSTERS