Herschel observations of extra-ordinary sources: Detecting spiral arm clouds by CH absorption lines

S. -L. Qin, P. Schilke, C. Comito +67

We have observed CH absorption lines ($J=3/2,N=1\leftarrow J=1/2,N=1$) against the continuum source Sgr~B2(M) using the \textit{Herschel}/HIFI instrument. With the high spectral…