The structure of g34.3+0.2 deduced from multitransition molecular line observations of HCO+

Heaton, B.D. and Little, L.T. and Yamashita, T. and Davies, S.R. and Cunningham, C.T. and Monteiro, T.S. (1993) The structure of g34.3+0.2 deduced from multitransition molecular line observations of HCO+. Astronomy and Astrophysics, 278 (1). pp. 238-246. ISSN 0004-6361. (The full text of this publication is not available from this repository)

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Abstract

Extensive HCO+ and (HCO+)-C-13 observations of the molecular cloud associated with the galactic H II region G 34.3 + 0.2 are compared to spectra produced by a radiative transfer model based on the method of Rybicki and Stenholm. Initial model parameters, derived from both molecular line and sub-millimetre continuum observations, are refined until model spectra are in reasonable agreement with those observed, judged on peak brightness temperature, linewidth, lineshape, and radial intensity variation. The best fitting model with constant HCO+ abundance has a molecular hydrogen density which is constant out to a radius 0.1 pc but which falls as r-2.1 outside this out to r = 1.5 pc. There is a turbulent velocity component of FWHM 5 km s-1 and a constant infall velocity 1.5 km s-1. The [HCO+]/[(HCO+)-C-13] abundance ratio is 20. The HCO+ observations are compared with NH3 and dust continuum observations. A two component model for the cloud is suggested in which an outer halo in quasi-virial equilibrium is collapsing slowly onto an expanding hot compact core. HCO+ is relatively under-abundant in the core.

Item Type: Article
Uncontrolled keywords: Ism, Individual Objects, G34.3+0.2; ISM, Clouds; Ism, Molecules; Radio Lines, Interstellar
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Q Science > QC Physics
Divisions: Faculties > Science Technology and Medical Studies > School of Engineering and Digital Arts
Depositing User: M. Nasiriavanaki
Date Deposited: 30 Jul 2009 08:18
Last Modified: 30 Jul 2009 08:18
Resource URI: http://kar.kent.ac.uk/id/eprint/22135 (The current URI for this page, for reference purposes)
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