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.


stars: formation

galaxies: evolution

Local Group


ISM: clouds


galaxies: individual: M33


J. Braine

Laboratoire d'Astrophysique de Bordeaux

P. Gratier

Laboratoire d'Astrophysique de Bordeaux

C. Kramer

Instituto de Radioastronomía Milimétrica

E. M. Xilouris

National Observatory of Athens

E. Rosolowsky

University of British Columbia (UBC)

C. Buchbender

Instituto de Radioastronomía Milimétrica

M. Boquien

University of Massachusetts

D. Calzetti

University of Massachusetts

G. Quintana-Lacaci

Instituto de Radioastronomía Milimétrica

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

Instituto de Radioastronomía Milimétrica

C. Henkel

Max Planck Society

B. Koribalski

Australia Telescope National Facility

B. Mookerjea

Tata Institute of Fundamental Research

M. Roellig

University of Cologne

K. Schuster

Institut de RadioAstronomie Millimetrique (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 L69

Subject Categories

Astronomy, Astrophysics and Cosmology



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