- ID:
- ivo://CDS.VizieR/J/A+A/611/A6
- Title:
- ATLASGAL massive clumps H_2_CO data
- Short Name:
- J/A+A/611/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Formaldehyde (H_2_CO) is a reliable tracer to accurately measure the physical parameters of dense gas in star-forming regions. We aim to determine directly the kinetic temperature and spatial density with formaldehyde for the ~100 brightest ATLASGAL-selected clumps (the TOP100 sample) at 870um representing various evolutionary stages of high-mass star formation. Ten transitions (J=3-2 and 4-3) of ortho- and para-H2CO near 211, 218, 225, and 291GHz were observed with the Atacama Pathfinder EXperiment (APEX) 12m telescope.
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- ID:
- ivo://CDS.VizieR/J/A+A/601/A60
- Title:
- ATLASGAL: Massive cluster progenitors sample
- Short Name:
- J/A+A/601/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The progenitors of high-mass stars and clusters are still challenging to recognise. Only unbiased surveys, sensitive to compact regions of high dust column density, can unambiguously reveal such a small population of particularly massive and cold clumps. Here we use the ATLASGAL survey to identify a sample of candidate progenitors of massive clusters in the inner Galaxy. We characterise a flux limited sample of compact sources selected from the ATLASGAL survey. Sensitive mid-infrared data at 21-24um from the WISE and MIPSGAL surveys were explored to search for embedded objects, and complementary spectroscopic data were used to investigate their stability and their star formation activity. We identify an unbiased sample of infrared-quiet massive clumps in the Galaxy that potentially represent the earliest stages of massive cluster formation. An important fraction of this sample consists of sources that have not been studied in detail before. We first find that clumps hosting more evolved embedded objects and infrared-quiet clumps exhibit similar physical properties in terms of mass and size, suggesting that the sources are not only capable of forming high-mass stars, but likely also follow a single evolutionary track leading to the formation of massive clusters. The majority of the clumps are likely not in virial-equilibrium, suggesting collapse on the clump scale.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/1555
- Title:
- ATLASGAL massive star forming clumps sample
- Short Name:
- J/MNRAS/443/1555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By matching infrared-selected, massive young stellar objects (MYSOs) and compact HII regions in the Red MSX Source survey to massive clumps found in the submillimetre ATLASGAL (APEX Telescope Large Area Survey of the Galaxy) survey, we have identified ~1000 embedded young massive stars between 280{deg}<l<350{deg} and 10{deg}<l<60{deg} with |b|<1.5{deg}. Combined with an existing sample of radio-selected methanol masers and compact HII regions, the result is a catalogue of ~1700 massive stars embedded within ~1300 clumps located across the inner Galaxy, containing three observationally distinct subsamples, methanol-maser, MYSO and HII-region associations, covering the most important tracers of massive star formation, thought to represent key stages of evolution.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/400
- Title:
- ATLASGAL. Properties of compact HII regions
- Short Name:
- J/MNRAS/435/400
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete sample of molecular clumps containing compact and ultracompact HII (UC HII) regions between l=10{deg} and 60{deg} and |b|<1{deg}, identified by combining the APEX Telescope Large Area Survey of the Galaxy submm and CORNISH radio continuum surveys with visual examination of archival infrared data. Our sample is complete to optically thin, compact and UC HII regions driven by a zero-age main-sequence star of spectral type B0 or earlier embedded within a 1000M_{sun}_ clump. In total we identify 213 compact and UC HII regions, associated with 170 clumps. Unambiguous kinematic distances are derived for these clumps and used to estimate their masses and physical sizes, as well as the Lyman continuum fluxes and sizes of their embedded HII regions.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A160
- Title:
- ATLASGAL-selected massive clumps. Chemistry of PDR
- Short Name:
- J/A+A/644/A160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study ten molecular transitions obtained from an unbiased 3mm molecular line survey using the IRAM 30m telescope toward 409 compact dust clumps identified by the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) to better understand the photodissociation regions (PDRs) associated with these clumps. The main goal of this study is to investigate whether the abundances of the selected molecules show any variations resulting from the PDR chemistry in different clump environments. We selected HCO, HOC^+^, C_2_H, c-C_3_H_2_, CN, H^13^CN, HC^15^N, and HN^13^C as PDR tracers, and H^13^CO^+^ and C^18^O as dense gas tracers. By using estimated optical depths of C_2_H and H^13^CN and assuming optically thin emission for other molecular transitions, we derived the column densities of those molecules and their abundances. To assess the influence of the presence and strength of ultra- violet radiation, we compare abundances of three groups of the clumps: HII regions, infrared bright non-HII regions, and infrared dark non-HII regions. We detected C^18^O, H^13^CO^+^, C_2_H, c-C_3_H_2_, CN, and HN^13^C toward most of the observed dust clumps (detection rate >94%), and H^13^CN is also detected with a detection rate of 75%. On the other hand, HCO and HC^15^N show detection rates of 32% and 39%, respectively, toward the clumps, which are mostly associated with HII region sources: Detection rates of HCO and HC^15^N toward the HII regions are 66% and 79%. We find that the abundances of HCO, CN, C_2_H, and c-C_3_H_2_ decrease as the H_2_ column density increases, indicating high visual extinction, while those of high-density tracers (i.e., H^13^CO^+^ and HC^15^N) are constant. In addition, N(HCO)/N(H^13^CO^+^) ratios significantly decrease as H_2_ column density increases, and, in particular, 82 clumps have X(HCO)>=10^-10^ and N(HCO)/N(H^13^CO^+^)>~1, which are indications of far-ultraviolet (FUV) chemistry. This suggests the observed HCO abundances are likely associated with FUV radiation illuminating the PDRs. We also find that high N(c-C_3_H_2_)/N(C_2_H) ratios found for HII regions that have high HCO abundances (>~10^-10^) are associated with more evolved clumps with high L_bol_/M_clump_. This trend might be associated with gain-surface processes, which determine the initial abundances of these molecules, and time-dependent effects in the clumps corresponding to the envelopes around dense PDRs and HII regions. In addition, some fraction of the measured abundances of the small hydrocarbons of the HII sources may be the result of the photodissociation of PAH molecules.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/2555
- Title:
- ATLAS 1.4GHz Data Release 2
- Short Name:
- J/MNRAS/441/2555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first of two papers describing the second data release (DR2) of the Australia Telescope Large Area Survey at 1.4GHz, which comprises deep wide-field observations in total intensity, linear polarization, and circular polarization over the Chandra Deep Field-South and European Large Area Infrared Space Observatory Survey-South 1 regions. DR2 improves upon the first data release by maintaining consistent data reductions across the two regions, including polarization analysis, and including differential number counts in total intensity and linear polarization. Typical DR2 sensitivities across the mosaicked multipointing images are 30{mu}Jy/beam at approximately 12"x6" resolution over a combined area of 6.4deg^2^. In this paper we present detailed descriptions of our data reduction and analysis procedures, including corrections for instrumental effects such as positional variations in image sensitivity, bandwidth smearing with a non-circular beam, and polarization leakage, and application of the BLOBCAT source extractor. We present the DR2 images and catalogues of components (discrete regions of radio emission) and sources (groups of physically associated radio components). We describe new analytic methods to account for resolution bias and Eddington bias when constructing differential number counts of radio components.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/4020
- Title:
- ATLAS 1.4GHz Data Release 3
- Short Name:
- J/MNRAS/453/4020
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third data release from the Australia Telescope Large Area Survey. These data combine the observations at 1.4GHz before and after upgrades to the Australia Telescope Compact Array reaching a sensitivity of 14{mu}Jy/beam in 3.6 deg^2^ over the Chandra Deep Field South (CDFS) and of 17{mu}Jy/beam in 2.7 deg^2^ over the European Large Area ISO Survey South 1 (ELAIS-S1). We used a variety of array configurations to maximize the uv coverage resulting in a resolution of 16 by 7-arcsec in CDFS and of 12 by 8-arcsec in ELAIS-S1. After correcting for peak bias and bandwidth smearing, we find a total of 3034 radio source components above 5{sigma} in CDFS, of which 514 (17 per cent) are considered to be extended. The number of components detected above 5{sigma} in ELAIS-S1 is 2084, of which 392 (19 per cent) are classified as extended. The catalogues include reliable spectral indices ({Delta}{alpha}<0.2) between 1.40 and 1.71GHz for ~350 of the brightest components.
- ID:
- ivo://CDS.VizieR/J/A+A/544/A38
- Title:
- ATLAS 2.3GHz observations of ELAIS-S1 and CDF-S
- Short Name:
- J/A+A/544/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Australia Telescope Large Area Survey (ATLAS) aims to image a 7deg^2^ region centred on the European Large Area ISO Survey - South 1 (ELAIS-S1) field and the Chandra Deep Field South (CDF-S) at 1.4GHz with high sensitivity (up to {sigma}~10uJy) to study the evolution of star-forming galaxies (SFGs) and Active Galactic Nuclei (AGN) over a wide range of cosmic time. We present here ancillary radio observations at a frequency of 2.3GHz obtained with the Australia Telescope Compact Array (ATCA). The main goal of this is to study the radio spectra of an unprecedented large sample of sources (~2000 observed, ~600 detected in both frequencies).
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/2342
- Title:
- ATLAS 5.5GHz survey of Chandra Deep Field South
- Short Name:
- J/MNRAS/426/2342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Star-forming galaxies are thought to dominate the sub-mJy radio population, but recent work has shown that low-luminosity active galactic nuclei (AGNs) can still make a significant contribution to the faint radio source population. Spectral indices are an important tool for understanding the emission mechanism of the faint radio sources. We have observed the extended Chandra Deep Field South at 5.5GHz using a mosaic of 42 pointings with the Australia Telescope Compact Array. Our image reaches an almost uniform sensitivity of ~12Jy rms over 0.25deg^2^ with a restoring beam of 4.9"x2.0", making ATLAS 5.5GHz survey one of the deepest 6cm surveys to date. We present the 5.5GHz catalogue and source counts from this field. We take advantage of the large amount of ancillary data in this field to study the 1.4 to 5.5GHz spectral indices of the sub-mJy population.
- ID:
- ivo://CDS.VizieR/J/A+A/397/1035
- Title:
- Atlas of B6-A2 hyper- and supergiants
- Short Name:
- J/A+A/397/1035
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an atlas of spectra of 5 emission-line stars: the low-luminosity luminous blue variables (LBVs) HD 168625 and HD 160529, the white hypergiants (and LBV candidates) HD 168607 and AS 314, and the supergiant HD 183143. The spectra were obtained with 2 echelle spectrometers at the 6-m telescope of the Russian Academy of Sciences in the spectral range 4800 to 6700{AA}, with a resolution of 0.4{AA}. We have identified 380 spectral lines and diffuse interstellar bands within the spectra. Specific spectral features of the objects are described.
