- ID:
- ivo://CDS.VizieR/J/AJ/133/1795
- Title:
- Globulettes in four HII regions
- Short Name:
- J/AJ/133/1795
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Some HII regions surrounding young stellar clusters contain tiny dusty clouds, which on photos look like dark spots or teardrops against a background of nebular emission. From our collection of H{alpha} images of 10 HII regions gathered at the Nordic Optical Telescope, we found 173 such clouds, which we call "globulettes", since they are much smaller than normal globules and form a distinct class of objects. Many globulettes are quite isolated and located far from the molecular shells and elephant trunks associated with the regions. Others are attached to the trunks (or shells), suggesting that globulettes may form as a consequence of erosion of these larger structures. None of our objects appear to contain stellar objects. The globulettes were measured for position, dimension, and orientation, and we find that most objects are smaller than 10kAU.
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- ID:
- ivo://CDS.VizieR/J/A+A/565/A107
- Title:
- Globulettes in the Carina nebula
- Short Name:
- J/A+A/565/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Small molecular cloudlets are abundant in many HII regions surrounding newborn stellar clusters. In optical images these so-called globulettes appear as dark silhouettes against the bright nebular background. We aim to make an inventory of the population of globulettes in the Carina nebula complex, and to derive sizes and masses for comparisons with similar objects found in other HII regions. The globulettes were identified from H{alpha} images collected at the Hubble Space Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/83
- Title:
- GMOS spectroscopic obs. of SNR candidates in M83
- Short Name:
- J/ApJ/839/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results from a spectrophotometric study sampling the 300 candidate supernova remnants (SNRs) in M83 identified through optical imaging with Magellan/IMACS and Hubble Space Telescope/WFC3. Of the 118 candidates identified based on a high [SII]{lambda}{lambda}6716,6731 to H{alpha} emission ratio, 117 show spectroscopic signatures of shock-heated gas, confirming them as SNRs-the largest uniform set of SNR spectra for any galaxy. Spectra of 22 objects with a high [OIII]{lambda}5007 to H{alpha} emission ratio, selected in an attempt to identify young ejecta-dominated SNRs like Cas A, reveal only one (previously reported) object with the broad (1000km/s) emission lines characteristic of ejecta-dominated SNRs, beyond the known SN1957D remnant. The other 20 [OIII]-selected candidates include planetary nebulae, compact HII regions, and one background QSO. Although our spectroscopic sample includes 22 SNRs smaller than 11pc, none of the other objects show broad emission lines; instead their spectra stem from relatively slow (~200km/s) radiative shocks propagating into the metal-rich interstellar medium of M83. With six SNe in the past century, one might expect more of M83's small-diameter SNRs to show evidence of ejecta; this appears not to be the case. We attribute their absence to several factors, including that SNRs expanding into a dense medium evolve quickly to the ISM-dominated phase, and that SNRs expanding into regions already evacuated by earlier SNe are probably very faint.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A141
- Title:
- G345.5+1.5 region multiwavelength study
- Short Name:
- J/A+A/623/A141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The star formation process requires the dust and gas present in the Milky Way to self-assemble into dense reservoirs of neutral material where the new generation of stars will emerge. Star-forming regions are usually studied in the context of Galactic surveys, but dedicated observations are sometimes needed when the study reaches beyond the survey area. A better understanding of the star formation process in the Galaxy can be obtained by studying several regions. This allows increasing the sample of objects (clumps, cores, and stars) for further statistical works and deeper follow-up studies. Here, we studied the G345.5+1.5 region, which is located slightly above the Galactic plane, to understand its star formation properties. We combined Large Apex BOlometer CAmera (LABOCA) and ^12^CO(4-3) transition line (NANTEN2) observations complemented with the Hi-GAL and Spitzer-GLIMPSE surveys to study the star formation toward this region. We used the Clumpfind algorithm to extract the clumps from the 870um and ^12^CO(4-3) data. Radio emission at 36cm was used to estimate the number of HII regions and to remove the contamination from the free-free emission at 870um. We employed color-color diagrams and spectral energy distribution (SED) slopes to distinguish between prestellar and protostellar clumps.We studied the boundedness of the clumps through the virial parameter. Finally, we estimated the star formation efficiency (SFE) and star formation rate (SFR) of the region and used the Schmidt-Kennicutt diagram to compare its ability to form stars with other regions of the Galactic plane. Of the 13 radio sources that we found using the MGPS-2 catalog, 7 are found to be associated with Hii regions corresponding to late-B or early-O stars. We found 45 870um clumps with diameters between 0.4 and 1.2pc and masses between 43M_{sun}_ and 3923M_{sun}_, and 107 ^12^CO clumps with diameters between 0.4 pc and 1.3pc and masses between 28M_{sun}_ and 9433M_{sun}_. More than 50% of the clumps are protostellar and bounded and are able to host (massive) star formation. High SFR and SFR density (S FR) values are associated with the region, with an SFE of a few percent. With submillimeter, CO transition, and short-wavelength infrared observations, our study reveals a population of massive stars, protostellar and bound starless clumps, toward G345.5+1.5. This region is therefore actively forming stars, and its location in the starburst quadrant of the Schmidt-Kennicutt diagram is comparable to other star-forming regions found within the Galactic plane.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/2003
- Title:
- G305 star-forming complex in ^13^CO
- Short Name:
- J/MNRAS/435/2003
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 109-115GHz (3mm) wide-field spectral line observations of ^12^CO, ^13^CO and C^18^O J=1-0 molecular emission and 5.5 and 8.8GHz (6 and 3cm) radio continuum emission towards the high-mass star-forming complex known as G305. The morphology of G305 is dominated by a large evacuated cavity at the centre of the complex driven by clusters of O stars surrounded by molecular gas. Our goals are to determine the physical properties of the molecular environment and reveal the relationship between the molecular and ionized gas and star formation in G305. This is in an effort to characterize the star-forming environment and constrain the star formation history in an attempt to evaluate the impact of high-mass stars on the evolution of the G305 complex. Analysis of CO emission in G305 reveals 156 molecular clumps with the following physical characteristics; excitation temperatures ranging from 7 to 25K, optical depths of 0.2-0.9, H_2_) column densities of 0.1-4.0x10^22^cm^-2^, clump masses ranging from 10^2^ to 10^4^M_{sun}_ and a total molecular mass of >3.5x10^5^M_{sun}_. The 5.5 and 8.8GHz radio continuum emission reveals an extended low surface brightness ionized environment within which we identify 15 large-scale features with a further eight smaller sources projected within these features. By comparing to mid-infrared emission and archival data, we identify nine HII regions, seven compact HII regions, one UC HII region and four extended regions. The total integrated flux of the radio continuum emission at 5.5GHz is ~ 180Jy corresponding to a Lyman continuum output of 2.4x10^50^photons/s. We compare the ionized and molecular environment with optically identified high-mass stars and ongoing star formation, identified from the literature. Analysis of this data set reveals a star formation rate of 0.008-0.016M_{sun}_/yr and efficiency of 7-12%, allows us to probe the star formation history of the region and discuss the impact of high-mass stars on the evolution of G305.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A54
- Title:
- G31.41+0.31 Stokes IQU images
- Short Name:
- J/A+A/630/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Submillimeter Array (SMA) 870um polarization observations of the hot molecular core G31.41+0.31 revealed one of the clearest examples up to date of an hourglass-shaped magnetic field morphology in a high-mass star-forming region. To better establish the role that the magnetic field plays in the collapse of G31.41+0.31, we carried out Atacama Large Millimeter/submillimeter Array (ALMA) observations of the polarized dust continuum emission at 1.3mm with an angular resolution four times higher than that of the previous (sub)millimeter observations to achieve an unprecedented image of the magnetic field morphology. We used ALMA to perform full polarization observations at 233GHz (Band 6). The resulting synthesized beam is 00.28"x00.20" which, at the distance of the source, corresponds to a spatial resolution of 875au. The observations resolve the structure of the magnetic field in G31.41+0.31 and allow us to study the field in detail. The polarized emission in the Main core of G31.41+0.41 is successfully fit with a semi-analytical magnetostatic model of a toroid supported by magnetic fields. The best fit model suggests that the magnetic field is well represented by a poloidal field with a possible contribution of a toroidal component of 10% of the poloidal component, oriented southeast to northwest at ~-44{deg} and with an inclination of ~-45{deg}. The magnetic field is oriented perpendicular to the northeast to southwest velocity gradient detected in this core on scales from 10^3^-10^4^au. This supports the hypothesis that the velocity gradient is due to rotation of the core and suggests that such a rotation has little effect on the magnetic field. The strength of the magnetic field estimated in the central region of the core with the Davis-Chandrasekhar-Fermi method is ~8-13mG and implies that the mass-to-flux ratio in this region is slightly supercritical ({lambda}=1.4-2.2). The magnetic field in G31.41+0.31 maintains an hourglass-shaped morphology down to scales of <1000au. Despite the magnetic field being important in G31.41+0.31, it is not enough to prevent fragmentation and collapse of the core, as demonstrated by the presence of at least four sources embedded in the center of the core.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A2
- Title:
- Gum 31 870um continuum imgage
- Short Name:
- J/A+A/582/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are presenting here a study of the cold dust in the close environs of the ring nebula Gum 31. We aim at deriving the physical properties of the molecular gas and dust associated with the nebula, and investigating its correlation with the star formation in the region, that was probably triggered by the expansion of the ionization front against its environment. We make use of 870um emission data obtained with the Large APEX Bolometer Camera (LABOCA) to map the dust emission. The 870um emission provides an excellent probe of mass and density of dense molecular clouds. The obtained LABOCA image was compared to archival infrared, radio continuum, and optical images.
- ID:
- ivo://CDS.VizieR/VII/216
- Title:
- H-{alpha} emission regions in Southern Milky Way
- Short Name:
- VII/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Catalogue of Rodgers, Cambell, and Whiteoak (RCW), was the result of a survey of emission nebulae carried out at Mt. Stromlo Observatory from December 1957 to April 1959. The entire region of the Milky Way southward of the Palomar sky survey with a latitude of plus or minus 15 degrees of the galactic equator was photographed in the light of hydrogen alpha with comparison plates obtained in yellow light. This work roughly complements the Sharpless (Sh2, see Cat. <VII/20>) survey published in 1959.
- ID:
- ivo://CDS.VizieR/II/309
- Title:
- H{alpha} emission stars in the Orion Nebula
- Short Name:
- II/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog of 534 H{alpha} emission lines stars in the region of the Orion Nebula (5{deg}x5{deg}) is presented, an the basis of 240 "new" H{alpha} stars found on Tonantzintla spectral plates and previous known H{alpha} emission stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/2
- Title:
- H{alpha} fluxes of Galactic planetary nebulae
- Short Name:
- J/MNRAS/431/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of new integrated H{alpha} fluxes for 1258 Galactic planetary nebulae (PNe), with the majority, totalling 1234, measured from the Southern H{alpha} Sky Survey Atlas (SHASSA) and/or the Virginia Tech Spectral-line Survey (VTSS). Aperture photometry on the continuum-subtracted digital images was performed to extract H{alpha}+[NII] fluxes in the case of SHASSA, and H{alpha} fluxes from VTSS. The [NII] contribution was then deconvolved from the SHASSA flux using spectrophotometric data taken from the literature or derived by us. Comparison with previous work shows that the flux scale presented here has no significant zero-point error. Our catalogue is the largest compilation of homogeneously derived PN fluxes in any waveband yet measured, and will be an important legacy and fresh benchmark for the community. Amongst its many applications, it can be used to determine statistical distances for these PNe, determine new absolute magnitudes for delineating the faint end of the PN luminosity function, provide baseline data for photoionization and hydrodynamical modelling, and allow better estimates of Zanstra temperatures for PN central stars with accurate optical photometry. We also provide total H{alpha} fluxes for another 75 objects which were formerly classified as PNe, as well as independent reddening determinations for ~270 PNe, derived from a comparison of our H{alpha} data with the best literature H{beta} fluxes. In an appendix, we list corrected H{alpha} fluxes for 49 PNe taken from the literature, including 24 PNe not detected on SHASSA or VTSS, re-calibrated to a common zero-point.
