학술논문
Variations in H2O+/H2O ratios toward massive star-forming regions
Document Type
Working Paper
Author
Wyrowski, F.; van der Tak, F.; Herpin, F.; Baudry, A.; Bontemps, S.; Chavarria, L.; Frieswijk, W.; Jacq, T.; Marseille, M.; Shipman, R.; van Dishoeck, E. F; Benz, A. O.; Caselli, P.; Hogerheijde, M. R.; Johnstone, D.; Liseau, R.; Bachiller, R.; Benedettini, M.; Bergin, E.; Bjerkeli, P.; Blake, G.; Braine, J.; Bruderer, S.; Cernicharo, J.; Codella, C.; Daniel, F.; di Giorgio, A. M.; Dominik, C.; Doty, S. D.; Encrenaz, P.; Fich, M.; Fuente, A.; Giannini, T.; Goicoechea, J. R.; de Graauw, Th.; Helmich, F.; Herczeg, G. J.; Jørgensen, J. K.; Kristensen, L. E.; Larsson, B.; Lis, D.; McCoey, C.; Melnick, G.; Nisini, B.; Olberg, M.; Parise, B.; Pearson, J. C.; Plume, R.; Risacher, C.; Santiago, J.; Saraceno, P.; Tafalla, M.; van Kempen, T. A.; Visser, R.; Wampfler, S.; Yıldız, U. A.; Black, J. H.; Falgarone, E.; Gerin, M.; Roelfsema, P.; Dieleman, P.; Beintema, D.; De Jonge, A.; Whyborn, N.; Stutzki, J.; Ossenkopf, V.
Source
Subject
Language
Abstract
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 H2 O+ 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.
Comment: 5 pages, 4 figures, accepted for publication as a letter in the A&A Herschel-HIFI special issue
Comment: 5 pages, 4 figures, accepted for publication as a letter in the A&A Herschel-HIFI special issue