Herschel observations of EXtra-Ordinary Sources (HEXOS): detecting spiral arm clouds by CH absorption lines

Share and Export

Qin, S.-L., Schilke, P., Comito, C., Moller, T., Rolff, R., Muller, H.S.P., Belloche, A., Menten, K.M., Lis, D.C., Phillips , T.G., Bergin, E.A., Bell, T.A., Crockett, N.R., Blake, G.A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Gupta, H., Herbst, E., Joblin, C., Johnstone, D., Langer, W.D., Lord, S.D., Maret, S., Martin, P.G., Melnick, G.J., Morris, P., Murphy, J.Anthony, Neufeld, D.A., Ossenkopf, V., Pagani, L., Pearson, J.C., Perault, M., Plume, R., Salez, M., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Wang, S., Yorke, H.W., Yu, S., Zmuidzinas, J., Boogert, A., Gusten, R., Hartogh, P., Honingh, E., Karpov, A., Kooi, J., Krieg, J.-M., Schieder, R., Diez-Gonzalez, M.C., Bachiller, R., Martin-Pintado, J., Baechtold, W., Olberg, M., Nordh, L.H., Gill, J.L. and Chattopadhyay, G. (2010) Herschel observations of EXtra-Ordinary Sources (HEXOS): detecting spiral arm clouds by CH absorption lines. Astronomy & Astrophysics, 521 (L14). pp. 1-5. ISSN 0004-6361

PDF
AM_Spiral_Arm_Clouds.pdf
Download (141kB)

Abstract

We have observed CH absorption lines (J = 3/2, N = 1 ← J = 1/2, N = 1) against the continuum source Sgr B2(M) using the Herschel/HIFI instrument. With the high spectral resolution and wide velocity coverage provided by HIFI, 31 CH absorption features with different radial velocities and line widths are detected and identified. The narrower line width and lower column density clouds show “spiral arm” cloud characteristics, while the absorption component with the broadest line width and highest column density corresponds to the gas from the Sgr B2 envelope. The observations show that each “spiral arm” harbors multiple velocity components, indicating that the clouds are not uniform and that they have internal structure. This line-of-sight through almost the entire Galaxy offers unique possibilities to study the basic chemistry of simple molecules in diffuse clouds, as a variety of different cloud classes are sampled simultaneously. We find that the linear relationship between CH and H2 column densities found at lower AV by UV observations does not continue into the range of higher visual extinction. There, the curve flattens, which probably means that CH is depleted in the denser cores of these clouds.

Item Type:	Article
Additional Information:	© ESO 2010 The original publication is available at DOI: 10.1051/0004-6361/201015107
Keywords:	ISM; abundances; molecules; Herschel; HEXOS;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	4032
Depositing User:	Dr. Anthony Murphy
Date Deposited:	11 Dec 2012 16:24
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
Refereed:	Yes
Related URLs:	http://www.aanda.org/ http://publications.edpsciences.org/
URI:	https://mural.maynoothuniversity.ie/id/eprint/4032
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

MURAL - Maynooth University Research Archive Library

Herschel observations of EXtra-Ordinary Sources (HEXOS): detecting spiral arm clouds by CH absorption lines

Abstract

Repository Staff Only (login required)

Downloads

Origin of downloads