2010A&A...521L..16G

Query : 2010A&A...521L..16G

2010A&A...521L..16G - Astronomy and Astrophysics, volume 521, L16-16 (2010/10-1)

Interstellar CH absorption in the diffuse interstellar medium along the sight-lines to G10.6-0.4 (W31C), W49N, and W51.

GERIN M., DE LUCA M., GOICOECHEA J.R., HERBST E., FALGARONE E., GODARD B., BELL T.A., COUTENS A., KAZMIERCZAK M., SONNENTRUCKER P., BLACK J.H., NEUFELD D.A., PHILLIPS T.G., PEARSON J., RIMMER P.B., HASSEL G., LIS D.C., VASTEL C., BOULANGER F., CERNICHARO J., DARTOIS E., ENCRENAZ P., GIESEN T., GOLDSMITH P.F., GUPTA H., GRY C., HENNEBELLE P., HILY-BLANT P., JOBLIN C., KOLOS R., KRELOWSKI J., MARTIN-PINTADO J., MONJE R., MOOKERJEA B., PERAULT M., PERSSON C., PLUME R., SALEZ M., SCHMIDT M., STUTZKI J., TEYSSIER D., YU S., CONTURSI A., MENTEN K., GEBALLE T.R., SCHLEMMER S., MORRIS P., HATCH W.A., IMRAM M., WARD J.S., CAUX E., GUESTEN R., KLEIN T., ROELFSEMA P., DIELEMAN P., SCHIEDER R., HONINGH N. and ZMUIDZINAS J.

Abstract (from CDS):

We report the detection of the ground state N,J=1,3/2->1,1/2 doublet of the methylidyne radical CH at ∼532GHz and ∼536GHz with the Herschel/HIFI instrument along the sight-line to the massive star-forming regions G10.6-0.4 (W31C), W49N, and W51. While the molecular cores associated with these massive star-forming regions show emission lines, clouds in the diffuse interstellar medium are detected in absorption against the strong submillimeter background. The combination of hyperfine structure with emission and absorption results in complex profiles, with overlap of the different hyperfine components. The opacities of most of the CH absorption features are linearly correlated with those of CCH, CN, and HCO⁺ in the same velocity intervals. In specific narrow velocity intervals, the opacities of CN and HCO⁺ deviate from the mean trends, giving rise to more opaque absorption features. We propose that CCH can be used as another tracer of the molecular gas in the absence of better tracers, with [CCH]/[H₂] ∼3.2 ±1.1x10^–8. The observed [CN]/[CH], [CCH]/[CH] abundance ratios suggest that the bulk of the diffuse matter along the lines of sight has gas densities n_H=n(H)+2n(H₂) ranging between 100 and 1000cm^–3.

Abstract Copyright: ∼

Journal keyword(s): ISM: clouds - ISM: molecules - submillimeter: ISM - ISM: individual objects: G10.6-0.4 - ISM: individual objects: W49N - ISM: individual objects: W51

Simbad objects: 6

Full paper

View the references in ADS

Number of rows : 6

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Sp type	#ref 1850 - 2024	#notes
1	NAME Galactic Center	reg	17 45 39.60213	-29 00 22.0000	~	14048	0
2	NAME Sgr B2	MoC	17 47 20.4	-28 23 07	~	2217	1
3	W 31c	HII	18 10 29.1	-19 56 05	~	336	0
4	W 49n	HII	19 10 13.2	+09 06 12	~	464	3
5	W 51e4	HII	19 23 43.913	+14 30 29.49	B0.5	16	0
6	W 51	SNR	19 23 50	+14 06.0	~	1266	1

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