The Herschel M 33 extended survey (HerM33es): PACS spectroscopy of the star-forming region BCLMP 302
Journal article, 2011
Context. The emission line of [CII] at 158 mu m 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 [CII] 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 [CII] 158 mu m, [OI] 63 mu m, and other FIR lines in a 2' x 2' region of the northern spiral arm of M 33, centered on the HII region BCLMP302. At the peak of Ha emission, we observed in addition a velocity-resolved [CII] spectrum using HIFI. We use scatterplots to compare these data with PACS 160 mu m continuum maps, and with maps of CO and HI data, at a common resolution of 12 '' or 50 pc. Maps of Ha and 24 mu m emission observed with Spitzer are used to estimate the SFR. We created maps of the [CII] and [OI] 63 mu m emission and detected [NII] 122 mu m and [NIII] 57 mu m at individual positions. Results. The [CII] line observed with HIFI is significantly broader than that of CO, and slightly blue-shifted. In addition, there is little spatial correlation between [CII] observed with PACS and CO over the mapped region. There is even less spatial correlation between [CII] and the atomic gas traced by HI. Detailed comparison of the observed intensities towards the HII region with models of photo-ionization and photon-dominated regions, confirms that a significant fraction, 20-30%, of the observed [CII] emission stems from the ionized gas and not from the molecular cloud. The gas heating efficiency, using the ratio of [CII] to the TIR as a proxy, varies between 0.07 and 1.5%, with the largest variations found outside the HII region.
long-wavelength spectrometer
nearby galaxies
herm33es
photodissociation regions
m emission
galaxies
interstellar-medium
conditions
photon-dominated regions
star formation
HII regions
h-ii regions
M 33
physical
photon-dominated region (PDR)
m33
far-infrared spectroscopy
Author
B. Mookerjea
Tata Institute of Fundamental Research
C. Kramer
Institut de Radioastronomie Millimétrique (IRAM)
C. Buchbender
Institut de Radioastronomie Millimétrique (IRAM)
M. Boquien
University of Massachusetts
S. Verley
Universidad de Granada
M. Relano
Universidad de Granada
G. Quintana-Lacaci
Institut de Radioastronomie Millimétrique (IRAM)
Susanne Aalto
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
J. Braine
Laboratoire d'Astrophysique de Bordeaux
D. Calzetti
University of Massachusetts
F. Combes
Centre national de la recherche scientifique (CNRS)
S. G. Burillo
P. Gratier
Max Planck Society
C. Henkel
Max Planck Society
F. P. Israel
Leiden University
S. Lord
California Institute of Technology (Caltech)
T. Nikola
Cornell University
M. Rollig
University of Cambridge
University of Cologne
G. Stacey
Cornell University
F. Tabatabaei
Max Planck Society
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
P. van der Werf
University of Edinburgh
Leiden University
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 532 art. no. A152- A152Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201116447