Highlight: Herschel/HIFI discovery of interstellar chloronium (H2Cl+) (vol. 521)

Vol. 521In section 1. Letters to the Editor1st October 2010

Herschel/HIFI discovery of interstellar chloronium (H2Cl+)

by D. C. Lis, J. C. Pearson, D. A. Neufeld, P. Schilke, et al., A&A 521, L9 alt

One of the surprises of the first observations with the heterodyne spectrometer on the Herschel satellite (HIFI) has been the detection of a variety of ions in absorption towards strong background submillimeter sources in the galactic plane. These appear to form in diffuse clouds with an H2/H ratio of order unity. The paper by Lis et al highlighted in this issue describes the detection of chloronium or H2Cl+ towards the star forming regions NGC 6334 and Sgr B2. The inferred column densities are larger than predicted by simple models suggesting perhaps some of our ideas about diffuse clouds in the inner galaxy need revision.