CHEMICAL EVOLUTION IN HIGH-MASS STAR-FORMING REGIONS: RESULTS FROM THE MALT90 SURVEY
Autor: | Jonathan B. Foster, Andrés E. Guzmán, Jill Rathborne, Tatiana Vasyunina, Christopher Claysmith, J. Scott Whitaker, Patricio Sanhueza, James M. Jackson, Sadia Hoq, Anton Vasyunin |
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Rok vydání: | 2013 |
Předmět: |
Physics
Molecular line 010308 nuclear & particles physics Star formation FOS: Physical sciences Astronomy and Astrophysics Classification scheme Astrophysics Intensity ratio Astrophysics - Astrophysics of Galaxies 01 natural sciences Chemical evolution 13. Climate action Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences High mass Classification methods 010303 astronomy & astrophysics |
Zdroj: | Astrophysical Journal |
ISSN: | 1538-4357 0004-637X |
Popis: | The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary stages of dense molecular clumps associated with high-mass star formation. We use the molecular line maps from Year 1 of the Millimetre Astronomy Legacy Team 90 GHz (MALT90) Survey. The survey mapped several hundred individual star-forming clumps chosen from the ATLASGAL survey to span the complete range of evolution, from prestellar to protostellar to H II regions. The evolutionary stage of each clump is classified using the Spitzer GLIMPSE/MIPSGAL mid-IR surveys. Where possible, we determine the dust temperatures and H2 column densities for each clump from Herschel Hi-GAL continuum data. From MALT90 data, we measure the integrated intensities of the N2H+, HCO+, HCN and HNC (1-0) lines, and derive the column densities and abundances of N2H+ and HCO+. The Herschel dust temperatures increase as a function of the IR-based Spitzer evolutionary classification scheme, with the youngest clumps being the coldest, which gives confidence that this classification method provides a reliable way to assign evolutionary stages to clumps. Both N2H+ and HCO+ abundances increase as a function of evolutionary stage, whereas the N2H+ (1-0) to HCO+ (1-0) integrated intensity ratios show no discernable trend. The HCN (1-0) to HNC(1-0) integrated intensity ratios show marginal evidence of an increase as the clumps evolve. |
Databáze: | OpenAIRE |
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