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Issue A&A
Volume 454, Number 2, August I 2006
APEX Special Booklet
Page(s) L95 - L98
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20065565



A&A 454, L95-L98 (2006)
DOI: 10.1051/0004-6361:20065565

Letter

Mid- and high-J CO observations towards ultracompact HII regions

F. Wyrowski, S. Heyminck, R. Güsten and K. M. Menten

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
    e-mail: wyrowski@mpifr-bonn.mpg.de

(Received 8 May 2006 / Accepted 18 May 2006)

Abstract
Aims.A study of 12 ultracompact HII regions was conducted to probe the physical conditions and kinematics in the inner envelopes of the molecular clumps harboring them.
Methods.The APEX telescope was used to observe the sources in the CO (4-3) and $^{13}{\rm CO}$ (8-7) lines. Line intensities were modeled with the RATRAN radiative transfer code using power laws for the density and temperature to describe the physical structure of the clumps.
Results.All sources were detected in both lines. The optically thick CO (4-3) line shows predominantly blue skewed profiles reminiscent of infall.
Conclusions.Line intensities can be reproduced well using the physical structure of the clumps taken from the literature. The optically thick line profiles show that CO is a sensitive tracer of ongoing infall in the outer envelopes of clumps harboring ultracompact HII regions and hot molecular cores.


Key words: stars: formation -- ISM: clouds -- ISM: kinematics and dynamics -- ISM: structure -- radio lines: ISM -- submillimeter



© ESO 2006


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