Variations in H2O+/H2O ratios toward massive star-forming regions
2010 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 521, L34- p.Article in journal (Refereed) Published
Early results from the Herschel Space Observatory revealed the water cation H2O+ to be an abundant ingredient of the interstellar medium. Here we present new observations of the H2O and H2O+ lines at 1113.3 and 1115.2 GHz using the Herschel Space Observatory toward a sample of high-mass star-forming regions to observationally study the relation between H2O and H2O+. Nine out of ten sources show absorption from H2O+ in a range of environments: the molecular clumps surrounding the forming and newly formed massive stars, bright high-velocity outflows associated with the massive protostars, and unrelated low-density clouds along the line of sight. Column densities per velocity component of H2O+ are found in the range of 10(12) to a few 10(13) cm(-2). The highest N(H2O+) column densities are found in the outflows of the sources. The ratios of H2O+/H2O are determined in a range from 0.01 to a few and are found to differ strongly between the observed environments with much lower ratios in the massive (proto) cluster envelopes (0.01-0.1) than in outflows and diffuse clouds. Remarkably, even for source components detected in H2O in emission, H2O+ is still seen in absorption.
Place, publisher, year, edition, pages
2010. Vol. 521, L34- p.
ISM: clouds, ISM: molecules, submillimeter: ISM, stars: formation
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-51361DOI: 10.1051/0004-6361/201015110ISI: 000284150900034OAI: oai:DiVA.org:su-51361DiVA: diva2:384827
authorCount :662011-01-102011-01-102011-01-10Bibliographically approved