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CH+(1-0) and 13CH+(1-0) absorption lines in the direction of massive star-forming regions

Edith Falgarone ; B. Godard ; J. Cernicharo ; M. de Luca ; M. Gerin ; T.G. Phillips ; John H. Black (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; D.C. Lis ; T. A. Bell ; F. Boulanger ; A. Coutens ; E. Dartois ; P. Encrenaz ; T. Giesen ; J.R. Goicoechea ; P.F. Goldsmith ; H. Gupta ; C. Gry ; P. Hennebelle ; E. Herbst ; P. Hily-Blant ; C. Joblin ; M. Kazmierczak ; R. Kolos ; J. Krelowski ; J. Martin-Pintado ; R. Monje ; B. Mookerjea ; D.A. Neufeld ; M. Perault ; J. C. Pearson ; Carina M. Persson (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; R. Plume ; M. Salez ; M. Schmidt ; P. Sonnentrucker ; J. Stutzki ; D. Teyssier ; C. Vastel ; S. Yu ; K. M. Menten ; T. R. Geballe ; S. Schlemmer ; R. Shipman ; A.G.G.M. Tielens ; S. Philipp ; A. Cros ; J. Zmuidzinas ; L.A. Samoska ; K. Klein ; A. Lorenzani ; R. Szczerba ; I. Peron ; P. Cais ; P. Gaufre ; L. Ravera ; P. Morris ; S. Lord ; P. Planesas
Astronomy and Astrophysics (0004-6361). Vol. 521 (2010), p. Article Number: L15.
[Artikel, refereegranskad vetenskaplig]

We report the detection of the ground-state rotational transition of the methylidyne cation CH+ and its isotopologue (CH+)-C-13 toward the remote massive star-forming regions W33A, W49N, and W51 with the HIFI instrument onboard the Herschel satellite. Both lines are seen only in absorption against the dust continuum emission of the star-forming regions. The CH+ absorption is saturated over almost the entire velocity ranges sampled by the lines-of-sight that include gas associated with the star-forming regions (SFR) and Galactic foreground material. The CH+ column densities are inferred from the optically thin components. A lower limit of the isotopic ratio [(CH+)-C-12]/[(CH+)-C-13]> 35.5 is derived from the absorptions of foreground material toward W49N. The column density ratio, N(CH+)/N(HCO+), is found to vary by at least a factor 10, between 4 and > 40, in the Galactic foreground material. Line-of-sight 12CH+ average abundances relative to total hydrogen are estimated. Their average value, N(CH+)/NH > 2.6 x 10(-8), is higher than that observed in the solar neighborhood and confirms the high abundances of CH+ in the Galactic interstellar medium. We compare this result to the predictions of turbulent dissipation regions (TDR) models and find that these high abundances can be reproduced for the inner Galaxy conditions. It is remarkable that the range of predicted N(CH+)/ N(HCO+) ratios, from 1 to similar to 50, is comparable to that observed.

Nyckelord: astrochemistry; ISM: molecules; ISM: kinematics and dynamics; turbulence

Denna post skapades 2010-12-27. Senast ändrad 2015-07-10.
CPL Pubid: 131852


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