870 micron continuum observations of the bubble-shaped nebula Gum 31

Abstract

We are presenting here a study of the cold dust in the infrared ring nebula Gum 31. We aim at deriving the physical properties of the molecular gas and dust associated with the nebula, and investigating its correlation with the star formation in the region, that was probably triggered by the expansion of the ionization front. We use 870 micron data obtained with LABOCA to map the dust emission. The obtained LABOCA image was compared to archival IR,radio continuum, and optical images. The 870 micron emission follows the 8 micron (Spitzer), 250 micron, and 500 micron (Herschel) emission distributions showing the classical morphology of a spherical shell. We use the 870 micron and 250 micron images to identify 60 dust clumps in the collected layers of molecular gas using the Gaussclumps algorithm. The clumps have effective deconvolved radii between 0.16 pc and 1.35 pc, masses between 70 Mo and 2800 Mo, and volume densities between 1.1x10^3 cm^-3 and 2.04x10^5 cm^-3. The total mass of the clumps is 37600 Mo. The dust temperature of the clumps is in the range from 21 K to 32 K, while inside the HII region reaches ~ 40 K. The clump mass distribution is well-fitted by a power law dN/dlog(M/Mo) proportional to M^(-alpha), with alpha=0.93+/-0.28. The slope differs from those obtained for the stellar IMF in the solar neighborhood, suggesting that the clumps are not direct progenitors of single stars/protostars. The mass-radius relationship for the 41 clumps detected in the 870 microns emission shows that only 37% of them lie in or above the high-mass star formation threshold, most of them having candidate YSOs projected inside. A comparison of the dynamical age of the HII region with the fragmentation time, allowed us to conclude that the collect and collapse mechanism may be important for the star formation at the edge of Gum 31, although other processes may also be acting.

15 pages, 10 figures. Accepted for publication in A&A

References in corpus (19)

• Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample
• Cold Dark Clouds: The Initial Conditions for Star Formation
• A Minimum Column Density of 1 g cm^-2 for Massive Star Formation
• The Large and Small Scale Structures of Dust in the Star-Forming Perseus Molecular Cloud
• IR Dust Bubbles: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions
• ATLASGAL --- Environments of 6.7\,GHz methanol masers
• Star formation around RCW 120, the perfect bubble
• ATLASGAL-selected massive clumps in the inner Galaxy: I. CO depletion and isotopic ratios
• Triggered star formation on the borders of the Galactic HII region RCW 82
• Triggered massive-star formation on the borders of Galactic HII regions. IV- Star formation at the periphery of Sh2-212
• A Census of the Carina Nebula -- II. Energy Budget and Global Properties of the Nebulosity
• Molecular line mapping of the giant molecular cloud associated with RCW 106 - II. Column density and dynamical state of the clumps
• Mopra CO Observations of the Bubble HII Region RCW120
• PAH Strength and the Interstellar Radiation Field around the Massive Young Cluster NGC3603
• The molecular complex associated with the Galactic HII region Sh2-90: a possible site of triggered star formation
• Unveiling the birth and evolution of the HII region Sh2-173
• Sh2-205: II. Its quiescent stellar formation activity
• Molecular gas associated with IRAS 10361-5830
• Molecules, dust, and protostars in NGC 3503

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• The Carina Nebula and Gum 31 molecular complex III: The distribution of the 1-3 GHz radio continuum across the whole nebula
• Physical characterization of S169: A prototypical IR bubble associated with the massive star-forming region IRAS12326-6245