Open AccessC‐type shocks in the interstellar medium: profiles of CH + and CH absorption lines
Author(s) -
Flower D. R.,
Pineau des Forêts G.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01574.x
Subject(s) - physics , interstellar medium , interstellar cloud , shock wave , ion , absorption (acoustics) , astrophysics , dissociative recombination , line (geometry) , shock (circulatory) , atomic physics , recombination , galaxy , optics , medicine , biochemistry , chemistry , geometry , mathematics , quantum mechanics , gene , thermodynamics
We have computed optical absorption‐line profiles of CH + and CH, as predicted by a model of a C‐type shock propagating in a diffuse interstellar cloud. Both these species are produced in the shock wave in the reaction sequence that is initiated by C + (H 2 , H)CH + . Whilst CH + flows at the ion speed, CH, which forms in the dissociative recombination reaction CH + 3 (e − , H 2 )CH, flows at a speed which is intermediate between those of the ions and the neutrals. The predicted velocity shift between the CH + and CH line profiles is found to be no more than approximately 2 km s −1 , which is smaller than has previously been assumed. We also investigate OH and HCO + , finding that the correlation between their column densities, recently observed in the diffuse interstellar medium, can be reproduced by the model.