PACS and SPIRE photometer maps of M33: First results of the HERschel M33 Extended Survey (HERM33ES)
Journal article, 2010
Context. Within the framework of the HERM33ES key program, we are studying the star forming interstellar medium in the nearby, metal-poor spiral galaxy M33, exploiting the high resolution and sensitivity of Herschel. Aims. We use PACS and SPIRE maps at 100, 160, 250, 350, and 500 mu m wavelength, to study the variation of the spectral energy distributions (SEDs) with galacto-centric distance. Methods. Detailed SED modeling is performed using azimuthally averaged fluxes in elliptical rings of 2 kpc width, out to 8 kpc galacto-centric distance. Simple isothermal and two-component grey body models, with fixed dust emissivity index, are fitted to the SEDs between 24 mu m and 500 mu m using also MIPS/Spitzer data, to derive first estimates of the dust physical conditions. Results. The far-infrared and submillimeter maps reveal the branched, knotted spiral structure of M33. An underlying diffuse disk is seen in all SPIRE maps (250-500 mu m). Two component fits to the SEDs agree better than isothermal models with the observed, total and radially averaged flux densities. The two component model, with beta fixed at 1.5, best fits the global and the radial SEDs. The cold dust component clearly dominates; the relative mass of the warm component is less than 0.3% for all the fits. The temperature of the warm component is not well constrained and is found to be about 60 K +/- 10 K. The temperature of the cold component drops significantly from similar to 24 K in the inner 2 kpc radius to 13 K beyond 6 kpc radial distance, for the best fitting model. The gas-to-dust ratio for beta = 1.5, averaged over the galaxy, is higher than the solar value by a factor of 1.5 and is roughly in agreement with the subsolar metallicity of M33.
dust
extinction
galaxies: individual: M33
galaxies:
star-formation
milky-way
infrared structure
cold dust
emission
galaxies: evolution
galaxies: evolution
Local Group
galaxy m33
ISM
nearby
cloud
Author
C. Kramer
Institut de Radioastronomie Millimétrique (IRAM)
C. Buchbender
Institut de Radioastronomie Millimétrique (IRAM)
E. M. Xilouris
National Observatory of Athens
M. Boquien
University of Massachusetts
J. Braine
Laboratoire d'Astrophysique de Bordeaux
D. Calzetti
University of Massachusetts
S. Lord
California Institute of Technology (Caltech)
B. Mookerjea
Tata Institute of Fundamental Research
G. Quintana-Lacaci
Institut de Radioastronomie Millimétrique (IRAM)
M. Relano
University of Cambridge
G. Stacey
Cornell University
F. Tabatabaei
Max Planck Society
S. Verley
Universidad de Granada
Susanne Aalto
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
S. Akras
National Observatory of Athens
M. Albrecht
Argelander-Institut für Astronomie
S. Anderl
Argelander-Institut für Astronomie
R. Beck
Max Planck Society
F. Bertoldi
Argelander-Institut für Astronomie
F. Combes
Centre national de la recherche scientifique (CNRS)
M. Dumke
European Southern Observatory Santiago
S. G. Burillo
Spanish National Observatory (OAN)
M. Gonzalez
Institut de Radioastronomie Millimétrique (IRAM)
P. Gratier
Laboratoire d'Astrophysique de Bordeaux
R. Güsten
Max Planck Society
C. Henkel
Max Planck Society
F. P. Israel
Leiden University
B. Koribalski
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
A. Lundgren
European Southern Observatory Santiago
J. Martin-Pintado
Centro de Astrobiologia (CAB)
M. Rollig
University of Cologne
E. Rosolowsky
University of British Columbia (UBC)
K. Schuster
Institut de Radioastronomie Millimétrique (IRAM)
K. Sheth
California Institute of Technology (Caltech)
A. Sievers
Institut de Radioastronomie Millimétrique (IRAM)
J. Stutzki
University of Cologne
R. P. J. Tilanus
F. F. S. van der Tak
Netherlands Institute for Space Research (SRON)
P. van der Werf
Leiden University
M. C. Wiedner
Centre national de la recherche scientifique (CNRS)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 518 Article Number: L67 L67Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201014613