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Title: THE CIRCUMNUCLEAR STAR FORMATION ENVIRONMENT OF NGC 6946: Br γ AND H{sub 2} RESULTS FROM KECK INTEGRAL FIELD SPECTROSCOPY

We present a three-dimensional data cube of the K-band continuum and the Br γ, H{sub 2} S(0), and S(1) lines within the central 18.''5 × 13.''8 (520 pc × 390 pc) region of NGC 6946. Data were obtained using OSIRIS, a near-infrared Integral Field Spectrograph at Keck Observatory, with Laser Guide Star Adaptive Optics. The 0.''3 resolution allows us to investigate the stellar bulge and the forming star clusters in the nuclear region on 10 pc scales. We detect giant H II regions associated with massive young star clusters in the nuclear spiral/ring (R ∼ 30 pc) and in the principal shocks along the nuclear bar. Comparisons of the Br γ fluxes with Pa α line emission and radio continuum indicate A{sub K} ∼ 3, A{sub V} ∼ 25 for the nuclear star-forming regions. The most luminous H II regions are restricted to within 70 pc of the center, despite the presence of high gas columns at larger radii (R ∼ 200 pc). H{sub 2} emission is restricted to clouds within R ∼ 60 pc of the center, resembling the distribution of HCN line emission. We propose that gas-assisted migration of the young star clusters is contributing to the buildupmore » of the nuclear bar and nuclear star cluster (R < 30 pc) in this galaxy.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States)
  3. Department of Physics and Astronomy, Tel Aviv University, Ramat Aviv (Israel)
  4. Department of Physics, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States)
  5. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario (Canada)
Publication Date:
OSTI Identifier:
22270754
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 776; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; BROMINE; COMPARATIVE EVALUATIONS; GALAXIES; H2 REGIONS; HYDROCYANIC ACID; HYDROGEN; INFRARED SPECTRA; NEAR INFRARED RADIATION; STAR CLUSTERS; STAR EVOLUTION; STARS; THREE-DIMENSIONAL CALCULATIONS