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Title: Submillimeter array and very large array observations in the hypercompact H II region G35.58-0.03

The formation of hypercompact (HC) H II regions is an important stage in massive star formation. Spectral line and continuum observations can explore its dynamic conditions. We present high angular resolution observations carried out with the Submillimeter Array (SMA) and the Very Large Array (VLA) toward the HC H II region G35.58-0.03. With the 1.3 mm SMA and 1.3 cm VLA, we detected a total of about 25 transitions of 8 different species and their isotopologues (CO, CH{sub 3}CN, SO{sub 2}, CH{sub 3}CCH, OCS, CS, H, and NH{sub 3}). G35.58-0.03 consists of an HC H II core with electron temperature T{sub e}{sup ∗}≧5500 K, emission measure EM ≈1.9 × 10{sup 9} pc cm{sup –6}, local volume electron density n{sub e} = 3.3 × 10{sup 5} cm{sup –3}, and a same width of radio recombination line FWHM ≈ 43.2 km s{sup –1} for both H30α and H38β at its intrinsic core size ∼3714 AU. The H30α line shows evidence of an ionized outflow driving a molecular outflow. Based on the derived Lyman continuum flux, there should be an early-type star equivalent to O6.5 located inside the H II region. From the continuum spectral energy distribution from 3.6 cm, 2.0 cm, 1.3more » cm, 1.3 mm and 0.85 mm to 0.45 mm, we distinguished the free-free emission (25% ∼ 55%) from the warm dust component (75% ∼ 45%) at 1.3 mm. The molecular envelope shows evidence of infall and outflow with an infall rate of 0.05 M {sub ☉} yr{sup –1} and a mass loss rate of 5.2 × 10{sup –3} M {sub ☉} yr{sup –1}. The derived momentum (∼0.05 M {sub ☉} km s{sup –1}) is consistent between the infalling and outflowing gas per year. It is suggested that the infall is predominant and the envelope mass of dense core is increasing rapidly, but the accretion in the inner part might already be halted.« less
Authors:
; ;  [1] ; ;  [2]
  1. National Astronomical Observatories, Chinese Academy of Sciences, 100012 Beijing (China)
  2. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
Publication Date:
OSTI Identifier:
22357284
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 784; 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; ACETONITRILE; AMMONIA; CARBON MONOXIDE; DUSTS; ELECTRON DENSITY; ELECTRON TEMPERATURE; EMISSION; ENERGY SPECTRA; LYMAN LINES; MASS TRANSFER; RESOLUTION; STARS; STELLAR WINDS; SULFUR DIOXIDE