HII region G46.5-0.2: the interplay between ionizing radiation, molecular gas and star formation
arXiv:1504.03935 · doi:10.1088/0004-6256/149/6/193
Abstract
HII regions are particularly interesting because they can generate dense layers of gas and dust, elongated columns or pillars of gas pointing towards the ionizing sources, and cometary globules of dense gas, where triggered star formation can occur. Understanding the interplay between the ionizing radiation and the dense surrounding gas is very important to explain the origin of these peculiar structures, and hence to characterize triggered star formation. G46.5-0.2 (G46), a poorly studied galactic HII region located at about 4 kpc, is an excellent target to perform this kind of studies. Using public molecular data extracted from the Galactic Ring Survey (13CO J=1-0) and from the James Clerk Maxwell Telescope data archive (12CO, 13CO, C18O J=3-2, HCO+ and HCN J=4-3), and infrared data from the GLIMPSE and MIPSGAL surveys, we perform a complete study of G46, its molecular environment and the young stellar objects placed around it. We found that G46, probably excited by an O7V star, is located close to the edge of the GRSMC G046.34-00.21 molecular cloud. It presents a horse-shoe morphology opening in direction of the cloud. We observed a filamentary structure in the molecular gas likely related to G46 and not considerable molecular emission towards its open border. We found that about 10' towards the southwest of G46 there are some pillar-like features, shining at 8 um and pointing towards the HII region open border. We propose that the pillar-like features were carved and sculpted by the ionizing flux from G46. We found several young stellar objects likely embedded in the molecular cloud grouped in two main concentrations: one, closer to the G46 open border consisting of Class II type sources, and other one mostly composed by Class I type YSOs located just ahead the pillars-like features, strongly suggesting an age gradient in the YSOs distribution.
arXiv commentAccepted for publication in The Astronomical Journal (April 14, 2015). Some figures were degraded to reduce file size
References in corpus (42)
- The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
- A computer program for fast non-LTE analysis of interstellar line spectra
- GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
- A new calibration of stellar parameters of Galactic O stars
- Mid-Infrared Selection of Active Galaxies
- Interpreting Spectral Energy Distributions from Young Stellar Objects. II. Fitting observed SEDs using a large grid of pre-computed models
- A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
- The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
- Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster
- The Third US Naval Observatory CCD Astrograph Catalog (UCAC3)
- The initial conditions of stellar protocluster formation. I. A catalogue of Spitzer dark clouds
- UBVJHK synthetic photometry of Galactic O stars
- Massive stars in massive clusters II: Disruption of bound clusters by photoionization
- How Many Infrared Dark Clouds can form Massive Stars and Clusters?
- Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
- HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope
- Ammonia from cold high-mass clumps discovered in the inner Galactic disk by the ATLASGAL survey
- A Galactic O-Star Catalog
- Resolution of the Distance Ambiguity for Galactic HII Regions
- Molecular gas in extreme star-forming environments: the starbursts Arp220 and NGC6240 as case studies
- New Infrared Emission Features and Spectral Variations in NGC 7023
- The Bolocam Galactic Plane Survey IX: Data Release 2 and Outer Galaxy Extension
- A 24 Micron Point Source Catalog of the Galactic Plane from Spitzer/MIPSGAL
- Detailed Numerical Simulations on the Formation of Pillars around HII-regions
- Radiation Driven Implosion of Molecular Cloud Cores
- Triggered massive-star formation on the borders of Galactic HII regions. IV- Star formation at the periphery of Sh2-212
- Radio Recombination Lines in Galactic HII Regions
- Molecular clouds and clumps in the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
- The JCMT Legacy Survey of the Gould Belt: a first look at Orion B with HARP
- Star formation triggered by HII regions in our Galaxy: First results for N49 from the Herschel infrared survey of the Galactic plane
- Dynamical Models for the Formation of Elephant Trunks in H II Regions
- Searching for signs of triggered star formation toward IC 1848
- Arcsecond-Resolution Submillimeter HCN Imaging of the Binary Protostar IRAS 16293-2422
- Young Stellar Objects and Triggered Star Formation in the Vulpecula OB Association
- A Compact Array imaging survey of southern bright-rimmed clouds
- Pillars and globules at the edges of H ii regions, Confronting Herschel observations and numerical simulations
- Testing Triggered Star Formation in Six H II Regions
- Dense molecular gas toward W49A: A template for extragalactic starbursts?
- The HII region G35.673-00.847: another case of triggered star formation?
- G048.66-0.29: Physical State of an Isolated Site of Massive Star Formation
- A bright-rimmed cloud sculpted by the H ii region Sh2-48
- Molecular excitation in the Eagle nebula's fingers