The infrared and molecular environment surrounding the Wolf-Rayet star WR130

We present a study of the molecular CO gas and mid/far infrared radiation arising from the environment surrounding the Wolf-Rayet (W-R) star 130. We use the multi-wavelength data to analyze the properties of the dense gas and dust, and its possible spatial correlation with that of Young Stellar Objects (YSOs). We use CO J=1-0 data from the FCRAO survey as tracer of the molecular gas, and mid/far infrared data from the recent WISE and Herschel space surveys to study the dust continuum radiation and to identify a population of associated candidate YSOs. The spatial distribution of the molecular gas shows a ring-like structure very similar to that observed in the HI gas, and over the same velocity interval. The relative spatial distribution of the HI and CO components is consistent with a photo-dissociation region. We have identified and characterized four main and distinct molecular clouds that create this structure. Cold dust is coincident with the dense gas shown in the CO measurements. We have found several cYSOs that lie along the regions with the highest gas column density, and suggest that they are spatially correlated with the shell. These are indicative of regions of star formation induced by the strong wind and ionization of the WR star.Comment: 15 pages, 12 figures, 6 Tables. Accepted for publication in MNRA

GS100-02-41: a new large HI shell in the outer part of the Galaxy

Massive stars have a profound effect on the surrounding interstellar medium. They ionize and heat the neutral gas, and due to their strong winds, they swept the gas up forming large HI shells. In this way, they generate a dense shell where the physical conditions for the formation of new stars are given. The aim of this study is to analyze the origin and evolution of the large HI shell GS100-02-41 and its role in triggering star forming processes.To characterize the shell and its environs, we carry out a multi-wavelength study. We analyze he HI 21 cm line, the radio continuum, and infrared emission distributions. The analysis of the HI data shows an expanding shell structure centred at (l, b) = (100.6 deg, -2.04 deg) in the velocity range from -29 to -51.7 km/s. We infer for GS100-02-41, a kinematical distance of 2.8 +/- 0.6 kpc. Several massive stars belonging to Cep OB1 are located in projection within the large HI, shell boundaries. The analysis of the radio continuum and infrared data reveal that there is no continuum counterpart of the HI shell. On the other hand, three slightly extended radio continuum sources are observed in projection onto the dense HI shell. From their flux density determinations we infer that they are thermal in nature. An analysis of the HI emission distribution in the environs of these sources shows, for each of them, a region of low emissivity having a good morphological correlation with the ionized gas in a velocity range similar to the one where GS100-02-41 is detected. The origin of GS100-02-41 could have been mainly due to the action of the Cep OB1 massive stars located inside the HI shell. The obtained age difference between the HI shell and the HII regions, together with their relative location, led us to conclude that the ionizing stars could have been created as a consequence of the shell evolution.Comment: Accepted for publication in A&

GSH 91.5+2-114: A large HI shell in the outer part of the Galaxy

GSH91.5+2-114 is a large HI shell located in the outer Galaxy at a kinematic distance of about 15 kpc. It was first identified in the Canadian Galactic Plane Survey (CGPS) by Pineault et al. (2002) as being possibly associated with objects possessing infrared colors which indicates strong stellar winds. The HI shell has no obvious continuum counterpart in the CGPS radio images at 408 and 1420 MHz or in the IRAS images. We found no evidence for early-type massive stars, most likely as a result of the large extinction that is expected for this large distance. An analysis of the energetics and of the main physical parameters of the HI shell shows that this shell is likely the result of the combined action of the stellar winds and supernova explosions of many stars. We investigate whether a number of slightly extended regions characterized by a thermal radio continuum and located near the periphery of the HI shell could be the result of star formation triggered by the expanding shell.Comment: Accepted for publication in A&A, October 2010. Some figures were degraded to reduce file siz

The antenna DSA 3 and its potential use for Radio Astronomy

The European Space Agency (ESA) will inaugurate its third Deep Space Antenna (DSA 3) by the end of 2012. DSA 3 will be located in Argentina near the city of Malarg"ue in the Mendoza province. While the instrument will be primarily dedicated to communications with interplanetary missions, the characteristics of its antenna and receivers will also enable standalone leading scientific contributions, with a high scientific-technological return. We outline here scientific proposals for a radio astronomical use of DSA 3.Comment: 4 pages, submitted as Proceedings for the BAA

The radio and IR counterparts of the ring nebula around HD211564

We report the detection of the radio and infrared counterparts of the ring nebula around the WN3(h) star HD211564 (WR152), located to the southwest of the HII region Sh2132. Using radio continuum data from the Canadian Galactic Plane Survey, we identified the radio counterparts of the two concentric rings, of about 9' and 16' in radius, related to the star. After applying a filling factor f = 0.05-0.12, electron densities and ionized masses are in the range 10-16 cm^-3 and 450-700 Mo, respectively. The analysis of the HI gas emission distribution allowed the identification of 5900 Mo of neutral atomic gas with velocities between -52 and -43 km/s probably linked to the nebula. The region of the nebula is almost free of molecular gas. Only four small clumps were detected, with a total molecular mass of 790 Mo. About 310 Mo are related to a small infrared shell-like source linked to the inner ring, which is also detected in the MSX band A. An IRAS YSO candidate is detected in coincidence with the shell-like IR source. We suggest that the optical nebula and its neutral counterparts originated from the stellar winds from the WR star and its massive progenitor, and are evolving in the envelope of a slowly expanding shell centered at (l,b) = (102 30, -0 50), of about 31 pc in radius. The bubble's energy conversion efficiency is in agreement with recent numerical analysis and with observational results.Comment: 11 pages, 7 figures, accepted in MNRA

The infrared and molecular environment surrounding the Wolf-Rayet star WR 130

We present a study of the molecular CO gas and mid/far-infrared radiation arising from the environment surrounding the Wolf-Rayet (WR) star 130. We use the multiwavelength data to analyse the properties of the dense gas and dust, and its possible spatial correlation with that of young stellar objects (YSOs). We use 12CO J=1-0 data from the Five College Radio Astronomy Observatory survey as tracer of the molecular gas, and mid/far-infrared data from the recent Wide-Field Infrared Survey Explorer (WISE) and Herschel space surveys to study the dust continuum radiation and to identify a population of associated candidate YSOs. The spatial distribution of the molecular gas shows a ring-like structure very similar to that observed in the H I gas, and over the same velocity interval. The relative spatial distribution of the H I and CO components is consistent with a photodissociation region. We have identified and characterized four main and distinct molecular clouds that create this structure. Cold dust is coincident with the dense gas shown in the CO measurements. We have found several young stellar object candidates that lie along the regions with the highest gas column density, and suggest that they are spatially correlated with the shell. These are indicative of regions of star formation induced by the strong wind and ionization of the WR star.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Physical characterization of S169: A prototypical IR bubble associated with the massive star-forming region IRAS12326-6245

With the aim of studying the properties of Galactic IR bubbles and their impact in massive star formation, we present a study of the IR bubble S169, associated with the massive star forming region IRAS12326-6245. We used CO(2-1),$^{13}$CO(2-1), C$^{18}$O(2-1), HCN(3-2), and HCO+(3-2) line data obtained with the APEX telescope to study the properties of the molecular gas in the nebula and the IRAS source . To analyze the properties and distribution of the dust, we used IRAC-GLIMPSE, Herschel, and ATLASGAL data. The properties of the ionized gas were studied using images obtained from the SUMSS survey and SuperCOSMOS database. In our search for stellar and protostellar objects in the region, we used IR and optical point source calalogs. The new APEX observations allowed us to identify three molecular components associated with the nebula, namely: at $-$39 km/s (component A), $-$25 km/s (component B), and $-$17 km/s (component C). Six molecular condensations (MC1 to MC6) were identified in component A, with MC3 (the densest and more massive one) being the molecular counterpart of IRAS12326-6245. For this source, we estimated an H$_2$ column density up to 8$\times$10$^{23}$ cm$^{-2}$. To explain the morphology and velocity of components A, B, and C, we propose a simple model consisting of a partially complete semisphere-like structure expanding at ~ 12 km/s. The introduction of this model has led to a discussion about the distance to both S169 and IRAS12326-6245, which was estimated to be ~ 2 kpc. Several candidate YSOs were identified, projected mostly onto the molecular condensations MC3, MC4, and MC5, which indicates that the star-formation process is very active at the borders of the nebula. A comparison between observable and modeled parameters was not enough to discern whether the collect-and-collapse mechanism is acting at the edge of S169.Comment: 17 pages, 12 figures. Accepted for publication in A&

A multiwavelength study of the star forming region IRAS 18544+0112

This work aims at investigating the molecular and infrared components in the massive young stellar object (MYSO) candidate IRAS 18544+0112. The purpose is to determine the nature and the origin of this infrared source. To analyze the molecular gas towards IRAS 18544+0112, we have carried out observations in a 90" x 90" region around l = 34.69, b = -0.65, using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J=3-2, 13CO J=3-2, HCO+ J=4-3 and CS J=7-6 lines with an angular resolution of 22". The infrared emission in the area has been analyzed using 2MASS and Spitzer public data. From the molecular analysis, we find self-absorbed 12CO J=3-2 profiles, which are typical in star forming regions, but we do not find any evidence of outflow activity. Moreover, we do not detect either HCO+ J=4-3 or CS J=7-6 in the region, which are species normally enhanced in molecular outflows and high density envelopes. The 12CO J=3-2 emission profile suggests the presence of expanding gas in the region. The Spitzer images reveal that the infrared source has a conspicuous extended emission bright at 8 um with an evident shell-like morphology of ~ 1.5 arcmin in size (~ 1.4 pc at the proposed distance of 3 kpc) that encircles the 24 um emission. The non-detection of ionized gas related to IRAS 18544+0112, together with the fact that it is still embedded in a molecular clump suggest that IRAS 18544+0112, has not reached the UCHII region stage yet. Based on near infrared photometry we search for YSO candidates in the region and propos that 2MASS 18565878+0116233 is the infrared point source associated with IRAS 18544+0112. Finally, we suggest that the expansion of a larger nearby HII region, G034.8-0.7, might be related to the formation of IRAS 18544+0112.Comment: 14 pages, accepted for publication in A&A. Figures degraded to reduce file siz

Outflowing activity in the UCHII region G045.47+0.05

Aims. This work aims at investigating the molecular gas in the surroundings of the ultra-compact HII region G045.47+0.05 looking for evidence of molecular outflows. Methods. We carried out observations towards a region of 2 arcmin x 2 arcmin centered at RA=19h 14m 25.6s, dec.= 11deg 09m 27.6s (J2000) using the Atacama Submillimeter Telescope Experiment (ASTE; Chile) in the 12CO J=3-2, 13CO J=3-2, HCO+ J=4-3 and CS J=7-6 lines with an angular resolution of 22 arcsec. We complement these observations with public infrared data. Results. We characterize the physical parameters of the molecular clump where G045.47+0.0 is embedded. The detection of the CS J=7-6 line emission in the region reveals that the ultra-compact HII region G045.47+0.0 has not completely disrupted the dense gas where it was born. The HCO+ abundance observed towards G045.47+0.0 suggests the presence of molecular outflow activity in the region. From the analysis of the 12CO J=3-2 transition we report the presence of bipolar molecular outflows with a total mass of about 300 solar masses . We derive a dynamical time (flow's age) of about 10^5 yr for the outflow gas, in agreement with the presence of an ultra-compact HII region. We identify the source 2MASS 19142564+1109283 as the massive protostar candidate to drive the molecular outflows. Based on the analysis of its spectral energy distribution we infer that it is an early B-type star of about 15 solar masses. The results of this work support the scenario where the formation of massive stars, at least up to early B-type stars, is similar to that of low mass stars.Comment: Recently accepted for publication in A&