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

The embedded clusters DBS 77, 78, 102, and 160-161 and their link with the interstellar medium

Aims. We report a study of the global properties of some embedded clusters placed in the fourth quadrant of the Milky Way to clarify some issues related with their location into the Galaxy and their stellar formation processes. Methods. We performed BVI photometric observations in the region of DBS 77, 78, 102, 160, and 161 clusters and infrared spectroscopy in DBS 77 region. They were complemented with JHK data from VVV survey combined with 2MASS catalogue, and used mid-infrared information from GLIMPSE catalogue. We also searched for HI data from SGPS and PMN radio surveys, and previous spectroscopic stellar classification. The spectroscopic and photometric information allowed us to estimate the spectral classification of the brightest stars of each studied region. On the other hand, we used the radio data to investigate the interstellar material parameters and the continuum sources probably associated with the respective stellar components. Results. We estimated the basic physical parameters of the clusters (reddening, distance, age, and initial mass function). We searched for HII regions located near to the studied clusters and we analyzed the possible link between them. In the particular case of DBS 160-161 clusters, we identified the HI bubble B332.5-0.1-42 located around them. We found that the mechanical energy injected to the interstellar medium by the more massive stars of this couple of clusters was enough to generate the bubble.Comment: 15 pages, 14 figures, 6 tables, accepted for publication in A&

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&

Impact of medications prescribed for treatment of attention-deficit hyperactivity disorder on physical growth in children and adolescents with HIV.

OBJECTIVE: To examine the relationships between physical growth and medications prescribed for symptoms of attention-deficit hyperactivity disorder in children with HIV. METHODS: Analysis of data from children with perinatally acquired HIV (N = 2251; age 3-19 years), with and without prescriptions for stimulant and nonstimulant medications used to treat attention-deficit hyperactivity disorder, in a long-term observational study. Height and weight measurements were transformed to z scores and compared across medication groups. Changes in z scores during a 2-year interval were compared using multiple linear regression models adjusting for selected covariates. RESULTS: Participants with (n = 215) and without (n = 2036) prescriptions were shorter than expected based on US age and gender norms (p \u3c .001). Children without prescriptions weighed less at baseline than children in the general population (p \u3c .001) but gained height and weight at a faster rate (p \u3c .001). Children prescribed stimulants were similar to population norms in baseline weight; their height and weight growth velocities were comparable with the general population and children without prescriptions (for weight, p = .511 and .100, respectively). Children prescribed nonstimulants had the lowest baseline height but were similar to population norms in baseline weight. Their height and weight growth velocities were comparable with the general population but significantly slower than children without prescriptions (p = .01 and .02, respectively). CONCLUSION: The use of stimulants to treat symptoms of attention-deficit hyperactivity disorder does not significantly exacerbate the potential for growth delay in children with HIV and may afford opportunities for interventions that promote physical growth. Prospective studies are needed to confirm these findings

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&

Vinculacion entre varios cúmulos estelares y estructuras del medio interestelar

Se estudiaron los cúmulos inmersos DBS 77, 78, 102, 160 y 161 localizados en el plano Galáctico en el cuarto cuadrante de la Vía Láctea y el medio interestelar (MIE) circundante. Se analizó fotometría UBVIc (SOAR) y espectroscopía infrarroja (NTT, ESO). Estos datos fueron complementados con las bandas JHK (VVV+2MASS), H I en 21 cm (SGPS), 1.4 GHz (ATCA) y 4.85 GHz (PMN). Se realizó un análisis multibanda y clasificación espectral de las estrellas brillantes de cada zona. Se identificaron también, estructuras del MIE posiblemente vinculadas con los cúmulos. Finalmente, se obtuvieron valores preliminares para los parámetros fundamentales de los cúmulos estudiados y de las estructuras del MIE. Se estudió la vinculación entre ambosWe study the embedded clusters DBS77, 78, 102, 160, and 161 located in the Galactic plane in the fourth quadrant of the Milky Way and the surrounding interstellar medium (ISM). We analyzed UBVIc photometry (SOAR) and infrared spectroscopy (NTT, ESO). We complemented these data with JHK (VVV2MASS), HI 21 cm bands (SGPS), 1.4 GHz (ATCA), and 4.85 GHz (PMN). We did multiband analysis and spectral classification of the brightest stars in each area. We also identified the ISM structures possibly related to the clusters. Finally, we obtained the main parameters of the studied clusters, the structures of the ISM and the link between them.Instituto de Astrofísica de La Plat

Vinculacion entre varios cúmulos estelares y estructuras del medio interestelar

Se estudiaron los cúmulos inmersos DBS 77, 78, 102, 160 y 161 localizados en el plano Galáctico en el cuarto cuadrante de la Vía Láctea y el medio interestelar (MIE) circundante. Se analizó fotometría UBVIc (SOAR) y espectroscopía infrarroja (NTT, ESO). Estos datos fueron complementados con las bandas JHK (VVV+2MASS), H I en 21 cm (SGPS), 1.4 GHz (ATCA) y 4.85 GHz (PMN). Se realizó un análisis multibanda y clasificación espectral de las estrellas brillantes de cada zona. Se identificaron también, estructuras del MIE posiblemente vinculadas con los cúmulos. Finalmente, se obtuvieron valores preliminares para los parámetros fundamentales de los cúmulos estudiados y de las estructuras del MIE. Se estudió la vinculación entre ambosWe study the embedded clusters DBS77, 78, 102, 160, and 161 located in the Galactic plane in the fourth quadrant of the Milky Way and the surrounding interstellar medium (ISM). We analyzed UBVIc photometry (SOAR) and infrared spectroscopy (NTT, ESO). We complemented these data with JHK (VVV2MASS), HI 21 cm bands (SGPS), 1.4 GHz (ATCA), and 4.85 GHz (PMN). We did multiband analysis and spectral classification of the brightest stars in each area. We also identified the ISM structures possibly related to the clusters. Finally, we obtained the main parameters of the studied clusters, the structures of the ISM and the link between them.Instituto de Astrofísica de La Plat

Vinculacion entre varios cúmulos estelares y estructuras del medio interestelar

Se estudiaron los cúmulos inmersos DBS 77, 78, 102, 160 y 161 localizados en el plano Galáctico en el cuarto cuadrante de la Vía Láctea y el medio interestelar (MIE) circundante. Se analizó fotometría UBVIc (SOAR) y espectroscopía infrarroja (NTT, ESO). Estos datos fueron complementados con las bandas JHK (VVV+2MASS), H I en 21 cm (SGPS), 1.4 GHz (ATCA) y 4.85 GHz (PMN). Se realizó un análisis multibanda y clasificación espectral de las estrellas brillantes de cada zona. Se identificaron también, estructuras del MIE posiblemente vinculadas con los cúmulos. Finalmente, se obtuvieron valores preliminares para los parámetros fundamentales de los cúmulos estudiados y de las estructuras del MIE. Se estudió la vinculación entre ambosWe study the embedded clusters DBS77, 78, 102, 160, and 161 located in the Galactic plane in the fourth quadrant of the Milky Way and the surrounding interstellar medium (ISM). We analyzed UBVIc photometry (SOAR) and infrared spectroscopy (NTT, ESO). We complemented these data with JHK (VVV2MASS), HI 21 cm bands (SGPS), 1.4 GHz (ATCA), and 4.85 GHz (PMN). We did multiband analysis and spectral classification of the brightest stars in each area. We also identified the ISM structures possibly related to the clusters. Finally, we obtained the main parameters of the studied clusters, the structures of the ISM and the link between them.Instituto de Astrofísica de La Plat

Radio emission from Supernova Remnants

The explosion of a supernova releases almost instantaneously about 10^51 ergs of mechanic energy, changing irreversibly the physical and chemical properties of large regions in the galaxies. The stellar ejecta, the nebula resulting from the powerful shock waves, and sometimes a compact stellar remnant, constitute a supernova remnant (SNR). They can radiate their energy across the whole electromagnetic spectrum, but the great majority are radio sources. Almost 70 years after the first detection of radio emission coming from a SNR, great progress has been achieved in the comprehension of their physical characteristics and evolution. We review the present knowledge of different aspects of radio remnants, focusing on sources of the Milky Way and the Magellanic Clouds, where the SNRs can be spatially resolved. We present a brief overview of theoretical background, analyze morphology and polarization properties, and review and critical discuss different methods applied to determine the radio spectrum and distances. The consequences of the interaction between the SNR shocks and the surrounding medium are examined, including the question of whether SNRs can trigger the formation of new stars. Cases of multispectral comparison are presented. A section is devoted to reviewing recent results of radio SNRs in the Magellanic Clouds, with particular emphasis on the radio properties of SN 1987A, an ideal laboratory to investigate dynamical evolution of an SNR in near real time. The review concludes with a summary of issues on radio SNRs that deserve further study, and analyzing the prospects for future research with the latest generation radio telescopes.Comment: Revised version. 48 pages, 15 figure