Triggered massive star formation associated with the bubble HII region Sh2-39 (N5)

Abstract

Aiming at studying the physical properties of Galactic IR bubbles and to explore their impact in triggering massive star formation, we perform a multiwavelength analysis of the bubble HII region Sh2-39 (N5) and its environs. To analyze the molecular gas we use CO(3-2) and HCO+(4-3) line data obtained with the ASTE telescope. To study the physical characteristics of the dust, we make use of archival data from ATLASGAL, Herschel, and MSX, while the ionized gas was studied making use of NVSS data. We use public IR point source catalogs to search for candidate YSOs in the region. To investigate the stellar cluster [BDS2003]6 we use IR spectroscopic data obtained with the ARCoIRIS spectrograph, and new available IR Ks band observations from VVVX survey. The new ASTE observations allowed the molecular gas component in the velocity range from 30 km/s to 46 km/s, associated with Sh2-39, to be studied in detail. We have identified four molecular clumps, that were likely formed by the expansion of the ionization front, and determined some of their physical and dynamical properties. Clumps having HCO+ and 870 micron counterparts show evidence of gravitational collapse. We identified several candidate YSOs across the molecular component. Their spatial distribution, as well as the fragmentation time derived for the collected layers of the molecular gas, suggest that massive star formation might have been triggered by the expansion of the nebula via the collect and collapse mechanism. The spectroscopical distance obtained for the stellar cluster [BDS2003]6, placed over one of the collapsing clumps, reveals that this cluster is physically associated with the neabula and gives more support to the triggered massive star formation scenario. A radio continuum data analysis indicates that the nebula is older and expands at lower velocity than typical Galactic IR bubbles.

14 pages, 8 figures. Accepted for publication in A&A

References in corpus (14)

• Theory of Star Formation
• Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample
• The UKIDSS Galactic Plane Survey
• UBVJHK synthetic photometry of Galactic O stars
• A Classification Scheme for Young Stellar Objects Using the WIDE-FIELD INFRARED SURVEY EXPLORER AllWISE Catalog: Revealing Low-Density Star Formation in the Outer Galaxy
• IR Dust Bubbles: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions
• Star formation around RCW 120, the perfect bubble
• The Electron Temperature Gradient in the Galactic Disk
• Triggered massive-star formation on the borders of Galactic HII regions. IV- Star formation at the periphery of Sh2-212
• New galactic star clusters discovered in the VVV survey. Candidates projected on the inner disk and bulge
• Mopra CO Observations of the Bubble HII Region RCW120
• 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
• The environs of the HII region Gum31

Cited by in corpus (6)

• APEX CO observations towards the photodissociation region of RCW120
• Molecular environs and triggered star formation around the large Galactic infrared bubble N 24
• Physical characterization of S169: A prototypical IR bubble associated with the massive star-forming region IRAS12326-6245
• Studying the interstellar medium to look for relics of triggered star formation among stellar clusters
• Three generations of stars: a possible case of triggered star formation
• KAgoshima Galactic Object survey with Nobeyama 45-metre telescope by Mapping in Ammonia lines (KAGONMA): Star formation feedback on dense molecular gas in the W33 complex