The environs of the HII region Gum31

Abstract

We analyze the distribution of the interstellar matter in the environs of the HII region Gum31, excited by the open cluster NGC3324, located in the complex Carina region, with the aim of investigating the action of the massive stars on the surrounding neutral material. We use neutral hydrogen 21-cm line data, radio continuum images at 0.843, 2.4 and 4.9 GHz, 12CO(1-0) observations, and IRAS and MSX infrared data. Adopting a distance of 3 kpc for the HII region and the ionizing cluster, we derived an electron density of 33+/-3 cm^-3 and an ionized mass of (3.3+/-1.1)x10^3 Mo based on the radio continuum data at 4.9 GHz. The HI 21-cm line images revealed an HI shell surrounding the HII region. The HI structure is 10.0+/-1.7 pc in radius, has a neutral mass of 1500+/-500 Mo, and is expanding at 11 km/s. The associated molecular gas amounts to 1.1+/-0.5)x10^5 Mo, being its volume density of about 350 cm^3. This molecular shell could represent the remains of the cloud where the young open cluster NGC3324 was born or could have originated by the shock front associated with the HII region. The difference between the ambient density and the electron density of the HII region suggests that the HII region is expanding. The distributions of the ionized and molecular material, along with that of the emission in the MSX band A, suggest that a photodissociation region has developed at the interface between the ionized and molecular gas. The characteristics of a relatively large number of the IRAS, MSX, and 2MASS point sources projected onto the molecular envelope are compatible with protostellar candidates, showing the presence of active star forming regions. Very probably, the expansion of the HII region has triggered stellar formation in the molecular shell.

References in corpus (13)

• A new calibration of stellar parameters of Galactic O stars
• The Southern Galactic Plane Survey: HI Observations and Analysis
• The Aao/Ukst Supercosmos H-alpha Survey (SHS)
• Triggered massive-star formation on the borders of Galactic HII regions. I. A search for `collect and collapse' candidates
• New infrared star clusters in the southern Milky Way with 2MASS
• Dynamical Expansion of Ionization and Dissociation Front around a Massive Star. II. On the Generality of Triggered Star Formation
• The Population of the Galactic Plane as Seen by MSX
• Ionisation-induced star formation I: The collect and collapse model
• High-Mass Cloud Cores in the eta Carinae Giant Molecular Cloud
• Dynamical Expansion of Ionization and Dissociation Front around a Massive Star. I. A Mode of Triggered Star Formation
• Star formation in RCW 108: triggered or spontaneous?
• Sequential star formation at the periphery of the HII regions Sh 217 and Sh 219
• Star clusterings in the Carina complex: UBVRI photometry of NGC 3324 and Loden 165

Cited by in corpus (18)

• Triggered star formation on the borders of the Galactic HII region RCW 120
• E-BOSS: an Extensive stellar BOw Shock Survey. I: Methods and First Catalogue
• Triggered star formation on the borders of the Galactic HII region RCW 82
• Exploring the origin of magnetic fields in massive stars: II. New magnetic field measurements in cluster and field stars
• Discovering young stars in the Gum 31 region with infrared observations
• Unveiling the birth and evolution of the HII region Sh2-173
• Flux calibration of the AAO/UKST SuperCOSMOS H-alpha Survey
• Energetic feedback and ${}^{26}$Al from massive stars and their supernovae in the Carina region
• Triggered massive star formation associated with the bubble HII region Sh2-39 (N5)
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- VI. On the formation of the "L" type filament in G286.21+0.17
• Star formation in the S233 region
• Chandra X-ray observation of the HII region Gum 31 in the Carina Nebula complex
• Census of High- and Medium-mass Protostars V. CO Abundance and the Galactic $X_{\text{CO}}$ Factor
• NGC 3503 and its molecular environment
• Molecular gas associated with IRAS 10361-5830
• An Expanding HI Photodissociated Region Associated with the Compact HII Region G213.880-11.837 in the GGD 14 Complex
• Massive star formation in the Carina nebula complex and Gum 31 -- II. a cloud-cloud collision in Gum 31
• Type-Ia Supernova Remnant Shell At $Z=3.5$ Seen In The Three Sightlines Toward The Gravitationally Lensed Qso B1422+231