The volume densities of giant molecular clouds in M83

Abstract

Using observed GALEX far-ultraviolet (FUV) fluxes and VLA images of the 21-cm HI column densities, along with estimates of the local dust abundances, we measure the volume densities of a sample of actively star-forming giant molecular clouds (GMCs) in the nearby spiral galaxy M83 on a typical resolution scale of 170 pc. Our approach is based on an equilibrium model for the cycle of molecular hydrogen formation on dust grains and photodissociation under the influence of the FUV radiation on the cloud surfaces of GMCs. We find a range of total volume densities on the surface of GMCs in M83, namely 0.1 - 400 cm-3 inside R25, 0.5 - 50 cm-3 outside R25 . Our data include a number of GMCs in the HI ring surrounding this galaxy. Finally, we discuss the effects of observational selection, which may bias our results.

arXiv comment9 pages, 11 figures

References in corpus (20)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The 'Forbidden' Abundance of Oxygen in the Sun
• The GALEX Ultraviolet Atlas of Nearby Galaxies
• The Second-Generation Guide Star Catalog: Description and Properties
• Recent Star Formation in the Extreme Outer Disk of M83
• The Cepheid Distance to NGC 5236 (M 83) with the VLT
• Optical spectroscopy of metal-rich HII regions and circumnuclear hot spots in M83 and NGC 3351
• Molecular gas in the galaxy M83. I - The molecular gas distribution
• Chemical and Photometric Evolution of Extended Ultraviolet Disks: Optical Spectroscopy of M83 (NGC5236) and NGC4625
• On The Extended Knotted Disks of Galaxies
• Evidence for the Large-Scale Dissociation of Molecular Gas in the Inner Spiral Arms of M81
• The Eastern Arm of M83 Revisited: High-Resolution Mapping of 12CO 1-0 Emission
• Extinction radial profiles of M83 from GALEX UV imaging
• A New Probe of the Molecular Gas in Galaxies: Application to M101
• The Production of HI in Photodissociation Regions and A Comparison with CO(1-0) Emission
• Dissecting the spiral galaxy M83: mid-infrared emission and comparison with other tracers of star formation
• The volume densities of GMCs in M81
• Molecular clouds in the center of M81
• Dynamical Formation of the Dark Molecular Hydrogen Clouds around Diffuse HII Regions
• Photodissociation and the Morphology of HI in Galaxies

Cited by in corpus (10)

• The Atomic to Molecular Transition in Galaxies. II: HI and H_2 Column Densities
• Quantified H i Morphology VII: The Morphology of Extended Disks in UV and H i
• Hα to FUV ratios in resolved star forming region populations of nearby spiral galaxies
• The JCMT Nearby Galaxies Legacy Survey VI: The distribution of gas and star formation in M81
• A photodissociation model for the morphology of the HI near OB associations in M33
• The Opacity of Spiral Galaxy Disks IX; Dust and Gas Surface Densities
• A new method for obtaining the star formation law in galaxies
• Hydrogen volume densities in nearby galaxies I - an automated approach
• Atomic Hydrogen produced in M33 Photodissociation Regions
• Environmental Effects on the Dynamical Evolution of Star Clusters in Turbulent Molecular Clouds