Journal Article

Probing the physical and chemical structure of the CS core in LDN 673: multitransitional and continuum observations

Oscar Morata, Josep Miquel Girart, Robert Estalella and Robin T. Garrod

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 425, issue 3, pages 1980-1991
Published in print September 2012 | ISSN: 0035-8711
Published online September 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21521.x
Probing the physical and chemical structure of the CS core in LDN 673: multitransitional and continuum observations

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Abstract

High angular resolution observations of dense molecular cores show that these cores can be clumpier at smaller scales and that some of these clumps can also be unbound or transient. The use of chemical models of the evolution of the molecular gas provides a way to probe the physical properties of the clouds. We study the properties of the clump and interclump medium in the starless CS core in LDN 673 by carrying out a molecular line survey with the IRAM 30-m telescope towards two clumps and two interclump positions. We also observed the 1.2-mm continuum with the MAMBO-II bolometer at IRAM. The dust continuum map shows four condensations, three of them centrally peaked, coinciding with previously identified submillimetre sources. We confirm that the denser clump of the region, n ∼ 3.6 × 105 cm−3, is also the more chemically evolved, and it could still undergo further fragmentation. The interclump medium positions are denser than previously expected, likely n ∼ 1 × 103–1 × 104 cm−3 due to contamination, and are chemically young, similar to the gas in the lower density clump position. We argue that the density contrast between these positions and their general young chemical age would support the existence of transient clumps in the lower density material of the core. We were also able to find reasonable fits of the observationally derived chemical abundances to models of the chemistry of transient clumps.

Keywords: stars: formation; ISM: abundances; ISM: clouds; ISM: individual objects: LDN 673; ISM: molecules; radio lines: ISM

Journal Article.  8304 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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