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Title: Subarcsecond observations of NGC 7538 IRS 1: Continuum distribution and dynamics of molecular gas

We report new results based on the analysis of the Submillimeter Array (SMA) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations of NGC 7538 IRS 1 at 1.3 and 3.4 mm with subarcsecond resolutions. With angular resolutions ∼0.''7, the SMA and CARMA observations show that the continuum emission at 1.3 and 3.4 mm from the hyper-compact H II region IRS 1 is dominated by a compact source with a tail-like extended structure to the southwest of IRS 1. With a CARMA B-array image at 1.3 mm convolved to 0.''1, we resolve the hyper-compact H II region into two components: an unresolved hyper-compact core, and a north-south extension with linear sizes of <270 AU and ∼2000 AU, respectively. The fine structure observed with CARMA is in good agreement with the previous Very Large Array results at centimeter wavelengths, suggesting that the hyper-compact H II region at the center of IRS 1 is associated with an ionized bipolar outflow. We image the molecular lines OCS(19-18) and CH{sub 3}CN(12-11) as well as {sup 13}CO(2-1) surrounding IRS 1, showing a velocity gradient along the southwest-northeast direction. The spectral line profiles in {sup 13}CO(2-1), CO(2-1), and HCN(1-0) observed toward IRS 1 show broadmore » redshifted absorption, providing evidence for gas infall with rates in the range of 3-10 × 10{sup –3} M {sub ☉} yr{sup –1} inferred from our observations.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ; ;  [6]
  1. National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012 (China)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Department of Astronomy, University of California, Berkeley, Berkeley, CA 94720 (United States)
  4. SOFIA-USRA, NASA Ames Research Center, MS 232-12, Building N232, Rm. 146, P.O. Box 1, Moffett Field, CA 94035-0001 (United States)
  5. Department of Astronomy, Peking University, Beijing 100871 (China)
  6. NRAO, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
Publication Date:
OSTI Identifier:
22348521
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 779; 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; ABSORPTION; ACETONITRILE; ASTRONOMY; CARBON 13; CARBON MONOXIDE; DISTRIBUTION; EMISSION; FINE STRUCTURE; GASES; HYDROCYANIC ACID; IMAGES; MOLECULES; RED SHIFT; RESOLUTION; WAVELENGTHS