The environs of the ultracompact HII region G45.45+0.06

Abstract

G45.45+0.06 is an ultra-compact HII (UCHII) region extensively studied. It is known that G45.45+0.06 is embedded in a complex of UCHII regions, but up the date, the surrounding ISM in a larger spatial scale has not been analyzed. Using data from large-scale surveys: Two Micron All Sky Survey, GLIMPSE, MIPSGAL, MAGPIS and GRS, we performed a multiwavelength study of a region about 7' x 7'in the vicinity of G45.45+0.06. We found that the UCHII complex lies in a border of a larger (diameter of ~ 3') and fainter HII region, which is located at the same distance as G45.45+0.06, ~ 8 kpc. In this work, this larger HII region was called G45L. A good morphological correlation is observed between the PDRs and the molecular gas mapped in the 13CO J=1--0 and CS J=2--1 lines, suggesting that G45L may be collecting the molecular material. From a near- and mid-IR photometric study, we found three sources, likely O-type stars, that are possibly responsible for the creation of G45L. Additionally we found several YSO candidates lying preferently in the molecular shell that surrounds G45L. Our results confirm that the region southeastern the UCHII complex where G45.45+0.06 is embedded and eastern G45L is active in star formation. We suggest that G45L has been expanding during about 2 x 10^6 yr and could have triggered the formation of the zero-age main sequence stars that are ionizing the UCHII region G45.45+0.06. However we can not discard that both HII regions are coeval.

17 pages, 13 figures, accepted for publication in A&A. July 2009

References in corpus (13)

• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• A Catalog of Extended Green Objects (EGOs) in the GLIMPSE Survey: A new sample of massive young stellar object outflow candidates
• The VLA Galactic Plane Survey
• UBVJHK synthetic photometry of Galactic O stars
• IR Dust Bubbles: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions
• Low sulfur depletion in the Horsehead PDR
• 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
• The Molecular Properties of Galactic HII Regions
• IR Dust Bubbles II: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions
• Unveiling the birth and evolution of the HII region Sh2-173
• The Ionizing Stars of the Galactic Ultra-Compact HII Region G45.45+0.06
• Modelling of aspherical nebulae. I. A quick pseudo-3D photoionization code

Cited by in corpus (8)

• Gas Kinematics and Star Formation in the Filamentary IRDC G34.43+0.24
• Simultaneous evidence of edge collapse and hub-filament configurations: A rare case study of a Giant Molecular Filament G45.3+0.1
• A statistical study of gaseous environment of Spitzer interstellar bubbles
• The BLAST View of the Star Forming Region in Aquila (ell=45deg,b=0deg)
• Two-Dimensional Molecular Gas and ongoing star formation around H II region Sh2-104
• Infrared study of the star-forming region associated with the UC HII regions G45.07+0.13 and G45.12+0.13
• Triggered massive and clustered stars formation by together H II regions G38.91-0.44 and G39.30-1.04
• Unveiling the circumstellar environment towards a massive young stellar object