Molecular environs and triggered star formation around the large Galactic infrared bubble N 24

Abstract

A multi-wavelength analysis of the large Galactic infrared bubble N 24 is has been presented in this paper in order to investigate the molecular and star formation environment around expanding HII regions. Using archival data from Herschel and ATLASGAL, the distribution and physical properties of the dust over the entire bubble are studied. Twenty three dense clumps are identified using the Clumpfind2d algorithm with sizes and masses in the range 0.65-1.73 pc and 600-16300 Msun, respectively. To analyse the molecular environment in N 24, observations of NH3 (1,1) and (2,2) were carried out using the Nanshan 26m radio telescope. Analysis of the kinetic temperature and gravitational stability of these clumps suggests gravitational collapse in several of them. The mass-size distributions of the clumps and the presence of massive young protostars indicate that the shell of N 24 is a region of ongoing massive star formation. The compatibility of the dynamical and fragmentation time-scales and the overabundance of YSOs and clumps on the rim suggest that the collect and collapse mechanism is in play at the boundary of the bubble, but the existence of the IRDC at the edge of bubble indicates that radiation-driven implosion mechanism may also have played a role there.

Accepted for publication in Monthly Notices of the Royal Astronomical Society

References in corpus (16)

• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• ATLASGAL --- properties of a complete sample of Galactic clumps
• The Large APEX Bolometer Camera LABOCA
• Ionisation-induced star formation I: The collect and collapse model
• The Perils of Clumpfind: The Mass Spectrum of Sub-structures in Molecular Clouds
• The dangers of being trigger--happy
• Ionisation-induced star formation II: External irradiation of a turbulent molecular cloud
• VLA observations of ammonia in high-mass star formation regions
• Dense core properties in the Infrared Dark cloud G14.225-0.506 revealed by ALMA
• Triggered massive-star formation on the borders of Galactic HII regions. III. Star formation at the periphery of Sh2-219
• The infrared dust bubble N22: an expanding HII region and the star formation around it
• A tale of two cores: Triggered massive star formation in the bright-rimmed cloud SFO 75
• Molecular outflows around high-mass young stellar objects
• Triggered massive star formation associated with the bubble HII region Sh2-39 (N5)
• Expanding Shell and Star Formation in the Infrared Dust Bubble N6

Cited by in corpus (2)

• Characterization of dense Planck clumps observed with Herschel and SCUBA-2
• Ammonia mapping observations of the Galactic infrared bubble N49: Three NH${}_3$ clumps along the molecular filament