- ID:
- ivo://CDS.VizieR/J/ApJS/166/567
- Title:
- Radio Molecular lines in infrared dark clouds
- Short Name:
- J/ApJS/166/567
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 41 infrared dark clouds from the 8um maps of the Midcourse Space Experiment (MSX), selected to be found within 1deg^2^ areas centered on known ultracompact HII regions. We have mapped these infrared dark clouds in N_2_H^+^ 1->0, CS 2->1, and C^18^O 1->0 emission using the Five College Radio Astronomy Observatory. The maps of the different species often show striking differences in morphologies, indicating differences in evolutionary state and/or the presence of undetected, deeply embedded protostars. We derive an average mass for these clouds using N_2_H^+^ column densities of >>2500M_{sun}_, a value comparable to that found in previous studies of high-mass star-forming cores using other mass tracers. The line widths of these clouds are typically 2.0-2.9km/s. Based on the fact that they are dark at 8um, compact, and massive, and have large velocity dispersions, we suggest that these clouds may be the precursor sites of intermediate- and high-mass star formation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/383/479
- Title:
- Radio obs. of optically obscured galaxies
- Short Name:
- J/MNRAS/383/479
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper analyses the radio properties of a subsample of optically obscured (R>=25.5) galaxies observed at 24um by the Spitzer Space Telescope within the First Look Survey. Ninety-six F24um>=0.35mJy objects out of 510 are found to have a radio counterpart at 1.4GHz, 610MHz or at both frequencies, respectively, down to ~40 and ~200uJy. IRAC photometry sets the majority of them in the redshift interval z~=[1-3] and allows for a broad distinction between active galactic nucleus (AGN) dominated galaxies (~47 per cent of the radio-identified sample) and systems powered by intense star formation (~13 per cent), the remaining objects being impossible to classify. The percentage of radio identifications is a strong function of 24-um flux: almost all sources brighter than F_24um_~2mJy are endowed with a radio flux at both 1.4GHz and 610MHz, while this fraction drastically decreases by lowering the 24-um flux level.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/48
- Title:
- Radio & opt/NIR counterparts of S2COSMOS submm galaxies
- Short Name:
- J/ApJ/886/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify multi-wavelength counterparts to 1147 submillimeter sources from the S2COSMOS SCUBA-2 survey of the COSMOS field by employing a recently developed radio+machine-learning method trained on a large sample of Atacama Large Millimeter/submillimeter Array (ALMA)-identified submillimeter galaxies (SMGs), including 260 SMGs identified in the AS2COSMOS pilot survey. In total, we identify 1222 optical/near-infrared (NIR)/radio counterparts to the 897 S2COSMOS submillimeter sources with S_850_>1.6mJy, yielding an overall identification rate of (78+/-9)%. We find that (22+/-5)% of S2COSMOS sources have multiple identified counterparts. We estimate that roughly 27% of these multiple counterparts within the same SCUBA-2 error circles very likely arise from physically associated galaxies rather than line-of-sight projections by chance. The photometric redshift of our radio+machine-learning-identified SMGs ranges from z=0.2 to 5.7 and peaks at z=2.3+/-0.1. The AGN fraction of our sample is (19+/-4)%, which is consistent with that of ALMA SMGs in the literature. Comparing with radio/NIR-detected field galaxy population in the COSMOS field, our radio+machine-learning-identified counterparts of SMGs have the highest star formation rates and stellar masses. These characteristics suggest that our identified counterparts of S2COSMOS sources are a representative sample of SMGs at z<~3. We employ our machine-learning technique to the whole COSMOS field and identified 6877 potential SMGs, most of which are expected to have submillimeter emission fainter than the confusion limit of our S2COSMOS surveys (S_850um_<~1.5mJy). We study the clustering properties of SMGs based on this statistically large sample, finding that they reside in high-mass dark matter halos ((1.2+/-0.3)x10^13^h^-1^M_{sun}_), which suggests that SMGs may be the progenitors of massive ellipticals we see in the local universe.
- ID:
- ivo://CDS.VizieR/J/AJ/102/1663
- Title:
- Radio properties of extragal. IRAS sources
- Short Name:
- J/AJ/102/1663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog presents radio and optical identifications of extragalactic IRAS sources from the IRAS Faint Source Catalog |b| > 50{deg} (Moshir et al., 1989 Cat. <II/156>). Sources with flux density > 0.2 at 60 microns and with S_60_ > S_12_ were identified by position coincidence with radio sources stronger than 25 mJy and lying north of declination = 5{deg} on the Green Bank 4.85 GHz sky map. Published VLA maps, new 4.86 GHz VLA maps made with 15 arcsec resolution, and accurate optical positions were used to confirm 122 candidate identifications. This catalog contains a merged version of tables 1 and 2 from the paper.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A131
- Title:
- Radio survey of ultracool dwarfs
- Short Name:
- J/A+A/549/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to increase the sample of ultracool dwarfs studied in the radio domain to allow a more statistically significant understanding of the physical conditions associated with these magnetically active objects. We conducted a volume-limited survey at 4.9GHz of 32 nearby ultracool dwarfs with spectral types covering the range M7-T8. A statistical analysis was performed on the combined data from the present survey and previous radio observations of ultracool dwarfs.
- ID:
- ivo://CDS.VizieR/J/A+A/350/883
- Title:
- R CrA ISOCAM observations
- Short Name:
- J/A+A/350/883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of an ISOCAM survey of the R CrA star formation region are presented. The survey was carried out in two broad-band filters, LW2 (5-8.5{mu}m) and LW3 (12-18{mu}m). Although it was not possible to map the densest, central region due to saturation problems, 21 sources were identified which showed mid-IR excesses. Most of these sources have not previously been recognised as YSOs (Young Stellar Objects), mainly because they are relatively faint. We find evidence for a population of very low mass stars which are probably brown dwarfs in their early contraction phases.
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/1609
- Title:
- RCW 106 Giant Molecular Cloud 13CO mapping
- Short Name:
- J/MNRAS/367/1609
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first paper in a series detailing the results of ^13^CO observations of a ~1{deg}^2^ region of the giant molecular cloud (GMC) complex associated with the HII region RCW 106. The ^13^CO observations are also the first stage of a multi-molecular line study of the same region. These observations were amongst the first made using the new on-the-fly mapping capability of the Australia Telescope National Facility Mopra Telescope. In the configuration used, the instrument provided a full width at half-maximum (FWHM) beam size of 33arcsec and a velocity resolution of 0.17km/s. The gas emission takes the form of a string of knots, oriented along an axis that extends from the north-west (NW) to the south-east (SE) of the field of the observations, and which is surrounded by a more extended, diffuse emission. We analyse the 2D integrated ^13^CO emission using the CLUMPFIND algorithm and identify 61 clumps. We compare the gas data in the GMC with the dust data provided by 21um Midcourse Space Experiment (MSX) and 1.2mm Swedish European Southern Observatory Submillimetre Telescope (SEST) images that we both regridded to the cell spacing of the Mopra data and smoothed to the same resolution.
- ID:
- ivo://CDS.VizieR/J/MNRAS/338/525
- Title:
- Recent star formation in UCM galaxies
- Short Name:
- J/MNRAS/338/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the integrated properties of the stellar populations in the Universidad Complutense de Madrid (UCM) Survey galaxies. Applying the techniques described in the first paper of this series (Perez-Gonzalez et al., 2003, Cat. <J/MNRAS/338/508>), we derive ages, burst masses and metallicities of the newly formed stars in our sample galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/115
- Title:
- Reddening, distance modulus & Fe/H of RRLs in w Cen
- Short Name:
- J/ApJ/870/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We developed a new approach to provide accurate estimates of the metal content, reddening, and true distance modulus of RR Lyrae stars (RRLs). The method is based on homogeneous optical (BVI) and near-infrared (JHK) mean magnitudes and on predicted period-luminosity-metallicity relations (IJHK) and absolute mean magnitude-metallicity relations (BV). We obtained solutions for three different RRL samples in {omega}Cen: first overtone (RRc, 90), fundamental (RRab, 80), and global (RRc+RRab) in which the period of first overtones were fundamentalized. The metallicity distribution shows a well defined peak at [Fe/H]~-1.98 and a standard deviation of {sigma}=0.54dex. The spread is, as expected, metal-poor ([Fe/H]<=-2.3) objects. The current metallicity distribution is ~0.3dex more metal-poor than similar estimates for RRLs available in the literature. The difference vanishes if the true distance modulus we estimated is offset by -0.06/-0.07mag in true distance modulus. We also found a cluster true distance modulus of {mu}=13.720{+/-}0.002{+/-}0.030mag, where the former error is the error on the mean and the latter is the standard deviation. Moreover, we found a cluster reddening of E(B-V)=0.132{+/-}0.002{+/-}0.028mag and spatial variations of the order of a few arcmin across the body of the cluster. Both the true distance modulus and the reddening are slightly larger than similar estimates available in the literature, but the difference is within 1{sigma}. The metallicity dependence of distance diagnostics agrees with theory and observations, but firm constraints require accurate and homogeneous spectroscopic measurements.
- ID:
- ivo://CDS.VizieR/J/MNRAS/410/1237
- Title:
- Red MSX survey (RMS) massive young stars
- Short Name:
- J/MNRAS/410/1237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red MSX Source (RMS) survey has identified a large sample of massive young stellar objects and ultra compact HII regions from a sample of ~2000 MSX and Two Micron All Sky Survey (2MASS) colour selected sources. Using a recent catalogue of molecular clouds derived from the Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS), and by applying a Galactic scaleheight cut-off of 120pc, we solve the distance ambiguity for RMS sources located within 18{deg}<|l|>54{deg}. These two steps yield kinematic distances to 291 sources out of a possible 326, located within the GRS longitude range. Combining distances and integrated fluxes derived from spectral energy distributions, we estimate luminosities to these sources and find that >90 per cent are indicative of the presence of a massive star. We find the completeness limit of our sample is ~10^4^L_{sun}_, which corresponds to a zero-age main-sequence star with a mass of ~12M_{sun}_. Selecting only these sources, we construct a complete sample of 196 sources.
