Mookerjea, B. and Kramer, C. and Buchbender, C. and Boquien, M. and Verley, S. and Relaño, M. and Quintana-Lacaci, G. and Aalto, S. and Braine, J. and Calzetti, D. and Combes, F. and García-Burillo, S. and Gratier, P. and Henkel, C. and Israel, F. and Lord, S. and Nikola, T. and Röllig, M. and Stacey, G. and Tabatabaei, F. S. and van der Tak, F. and van der Werf, P. (2011) The Herschel M 33 extended survey (HerM33es): PACS spectroscopy of the star-forming region BCLMP 302. Astronomy and Astrophysics, 532 . Art. No. A152. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20110928-101108669
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Context. The emission line of [C _(II)] at 158 μm is one of the strongest cooling lines of the interstellar medium (ISM) in galaxies. Aims. Distinguishing the relative contributions of the different ISM phases to [C _(II)] emission is a major objective of the HerM33es program, a Herschel key project to study the ISM in the nearby spiral galaxy M 33. Methods. Using PACS, we have mapped the emission of [C _(II)] 158 μm, [O _I] 63 μm, and other FIR lines in a 2'×2′ region of the northern spiral arm of M 33, centered on the H_(II) region BCLMP 302. At the peak of Hα emission, we observed in addition a velocity-resolved [C _(II)] spectrum using HIFI. We use scatterplots to compare these data with PACS 160 μm continuum maps, and with maps of CO and H_I data, at a common resolution of 12″ or 50 pc. Maps of Hα and 24 μm emission observed with Spitzer are used to estimate the SFR. We created maps of the [C _(II)] and [O_ I] 63 μm emission and detected [N _(II)] 122 μm and [N _(III)] 57 μm at individual positions. Results. The [C _(II)] line observed with HIFI is significantly broader than that of CO, and slightly blue-shifted. In addition, there is little spatial correlation between [C _(II)] observed with PACS and CO over the mapped region. There is even less spatial correlation between [C _(II)] and the atomic gas traced by H _I. Detailed comparison of the observed intensities towards the H _(II) region with models of photo-ionization and photon-dominated regions, confirms that a significant fraction, 20–30%, of the observed [C _(II)] emission stems from the ionized gas and not from the molecular cloud. The gas heating efficiency, using the ratio of [C _(II)] to the TIR as a proxy, varies between 0.07 and 1.5%, with the largest variations found outside the H _(II) region.
|Additional Information:||© 2011 ESO. Received 6 January 2011. Accepted 21 June 2011. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.|
|Subject Keywords:||galaxies: individual: M33; photon-dominated region (PDR); HII regions; Local Group; galaxies: ISM; galaxies: star formation|
|Official Citation:||The Herschel M 33 extended survey (HerM33es): PACS spectroscopy of the star-forming region BCLMP 302 B. Mookerjea, C. Kramer, C. Buchbender, M. Boquien, S. Verley, M. Relaño, G. Quintana-Lacaci, S. Aalto, J. Braine, D. Calzetti, F. Combes, S. Garcia-Burillo, P. Gratier, C. Henkel, F. Israel, S. Lord,, T. Nikola, M. Röllig, G. Stacey, F. S. Tabatabaei, F. van der Tak and P. van der Werf A&A 532 A152 (2011) DOI: 10.1051/0004-6361/201116447|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||29 Sep 2011 16:31|
|Last Modified:||26 Dec 2012 13:43|
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