Cool gas and dust in M33: Results from the HERschel M33 Extended Survey (HERM33ES)
Journal article, 2010
We present an analysis of the first space-based far-IR-submm observations of M33, which measure the emission from the cool dust and resolve the giant molecular cloud complexes. With roughly half-solar abundances, M33 is a first step towards young low-metallicity galaxies where the submm may be able to provide an alternative to CO mapping to measure their H-2 content. In this Letter, we measure the dust emission cross-section sigma using SPIRE and recent CO and HI observations; a variation in s is present from a near-solar neighborhood cross-section to about half-solar with the maximum being south of the nucleus. Calculating the total H column density from the measured dust temperature and cross-section, and then subtracting the HI column, yields a morphology similar to that observed in CO. The H-2/HI mass ratio decreases from about unity to well below 10% and is about 15% averaged over the optical disk. The single most important observation to reduce the potentially large systematic errors is to complete the CO mapping of M33.
galaxies:
galaxies: evolution
graphite
stars: formation
ISM: clouds
ISM
galaxies: individual: M33
Local Group
Author
J. Braine
Laboratoire d'Astrophysique de Bordeaux
P. Gratier
Laboratoire d'Astrophysique de Bordeaux
C. Kramer
Institut de Radioastronomie Millimétrique (IRAM)
E. M. Xilouris
National Observatory of Athens
E. Rosolowsky
University of British Columbia (UBC)
C. Buchbender
Institut de Radioastronomie Millimétrique (IRAM)
M. Boquien
University of Massachusetts
D. Calzetti
University of Massachusetts
G. Quintana-Lacaci
Institut de Radioastronomie Millimétrique (IRAM)
F. Tabatabaei
Max Planck Society
S. Verley
Universidad de Granada
F. P. Israel
Leiden University
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
Susanne Aalto
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
F. Combes
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
S. G. Burillo
Spanish National Observatory (OAN)
M. Gonzalez
Institut de Radioastronomie Millimétrique (IRAM)
C. Henkel
Max Planck Society
B. Koribalski
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
B. Mookerjea
Tata Institute of Fundamental Research
M. Roellig
University of Cologne
K. Schuster
Institut de Radioastronomie Millimétrique (IRAM)
M. Relano
University of Cambridge
F. Bertoldi
Argelander-Institut für Astronomie
P. van der Werf
Leiden University
M. C. Wiedner
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 518 Article Number: L69 L69Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201014551