- 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.
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Search Results
- 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/ApJS/211/29
- Title:
- Atlas of HI absorption toward HII regions in SGPS I
- Short Name:
- J/ApJS/211/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete catalog of H I emission and absorption spectrum pairs, toward H II regions, detectable within the boundaries of the Southern Galactic Plane Survey (SGPS I), a total of 252 regions. The catalog is presented in graphical, numerical, and summary formats. We demonstrate an application of this new data set through an investigation of the locus of the Near 3kpc Arm.
- ID:
- ivo://CDS.VizieR/J/ApJ/517/282
- Title:
- Atomic carbon observations of H II regions
- Short Name:
- J/ApJ/517/282
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report observations of atomic carbon (C I [^3^P - ^3^P_0_]) for a sample of 49 southern hemisphere H II regions using the Antarctic Submillimeter Telescope and Remote Observatory. The sources are compact and isolated members of the Wilson et al. (1970) H109{alpha} radio recombination line (RRL) catalog. The fourth Galactic quadrant is well covered by the sample. Atomic carbon emission is detected toward all of the regions, with multiple C I emission components found toward most sources. The RRL velocity is used to identify the C I emission associated with the H II region. We measure the mean velocity difference between the C I and RRL emission to be 0.8{+/-}2.8 km s^-1^. Within the measurement errors this is exact agreement in velocity; we conclude that all H II regions have associated C I emission. The mean C I line temperature of these components is 2.4{+/-}1.8 K, compared with 0.7{+/-}0.7 K for the C I emission components not associated with the H II region. This suggests that C I intensity is dominated by local heating. The FWHM line width of C I gas associated with H II regions also is marginally greater than that found for unassociated gas (6.7{+/-}3.0, compared with 4.8{+/-}2.4 km s-1).
- ID:
- ivo://CDS.VizieR/J/ApJ/835/55
- Title:
- AzTEC/ASTE survey at 1.1mm toward the SMC
- Short Name:
- J/ApJ/835/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first 1.1mm continuum survey toward the Small Magellanic Cloud (SMC) was performed using the AzTEC instrument installed on the ASTE 10m telescope. This survey covered 4.5deg^2^ of the SMC with 1{sigma} noise levels of 5-12mJy/beam, and 44 extended objects were identified. The 1.1mm extended emission has good spatial correlation with Herschel 160{mu}m, indicating that the origin of the 1.1mm extended emission is thermal emission from a cold dust component. We estimated physical properties using the 1.1mm and filtered Herschel data (100, 160, 250, 350, and 500{mu}m). The 1.1mm objects show dust temperatures of 17-45K and gas masses of 4x10^3^-3x10^5^M_{sun}_, assuming single-temperature thermal emission from the cold dust with an emissivity index, {beta}, of 1.2 and a gas-to-dust ratio of 1000. These physical properties are very similar to those of giant molecular clouds (GMCs) in our galaxy and the Large Magellanic Cloud. The 1.1mm objects also displayed good spatial correlation with the Spitzer 24{mu}m and CO emission, suggesting that the 1.1mm objects trace the dense gas regions as sites of massive star formation. The dust temperature of the 1.1mm objects also demonstrated good correlation with the 24{mu}m flux connected to massive star formation. This supports the hypothesis that the heating source of the cold dust is mainly local star-formation activity in the 1.1mm objects. The classification of the 1.1mm objects based on the existence of star-formation activity reveals the differences in the dust temperature, gas mass, and radius, which reflects the evolution sequence of GMCs.
- ID:
- ivo://CDS.VizieR/J/ApJ/727/114
- Title:
- BLAST 2005: a 10deg^2^ survey in Cygnus X
- Short Name:
- J/ApJ/727/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Cygnus X in a new multi-wavelength perspective based on an unbiased BLAST survey at 250, 350, and 500um, combined with rich data sets for this well-studied region. Our primary goal is to investigate the early stages of high-mass star formation. We have detected 184 compact sources in various stages of evolution across all three BLAST bands. From their well-constrained spectral energy distributions, we obtain the physical properties mass, surface density, bolometric luminosity, and dust temperature. Some of the bright sources reaching 40K contain well-known compact HII regions. We relate these to other sources at earlier stages of evolution via the energetics as deduced from their position in the luminosity-mass (L-M) diagram. The BLAST spectral coverage, near the peak of the spectral energy distribution of the dust, reveals fainter sources too cool (~10K) to be seen by earlier shorter-wavelength surveys like IRAS. We detect thermal emission from infrared dark clouds and investigate the phenomenon of cold "starless cores" more generally. Spitzer images of these cold sources often show stellar nurseries, but these potential sites for massive star formation are "starless" in the sense that to date there is no massive protostar in a vigorous accretion phase.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A8
- Title:
- Bubble HII region Sh2-39 (N5)
- Short Name:
- J/A+A/606/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aiming at studying the physical properties of Galactic IR bubbles and to explore their impact in triggering massive star formation, we perform a multiwavelength analysis of the bubble HII region Sh2-39 (N5) and its environs. To analyze the molecular gas we use CO(3-2) and HCO^+^(4-3) line data obtained with the on-the-fly technique from the ASTE telescope. To study the distribution and physical characteristics of the dust, we make use of archival data from ATLASGAL, Herschel, and MSX, while the ionized gas was studied making use of an NVSS image. We use public WISE, Spitzer, and MSX point source catalogs to search for infrared candidate YSOs in the region. To investigate the stellar cluster [BDS2003] 6 we use IR spectroscopic data obtained with the ARCoIRIS spectrograph, mounted on Blanco 4-m Telescope at CTIO, and new available IR Ks band observations from the VVVeXtended ESO Public Survey (VVVX). The new ASTE observations allowed the molecular gas component in the velocity range from 30km/s to 46km/s, associated with Sh2-39, to be studied in detail. The morphology of the molecular gas suggests that the ionized gas is expanding against its parental cloud. We have identified four molecular clumps, that were likely formed by the expansion of the ionization front, and determined some of their physical and dynamical properties. Clumps having HCO^+^ and 870um counterparts show evidence of gravitational collapse. We identified several candidate YSOs across the molecular component. Their spatial distribution, as well as the fragmentation time derived for the collected layers of the molecular gas, suggest that massive star formation might have been triggered by the expansion of the nebula via the collect and collapse mechanism. The spectroscopical distance obtained for the stellar cluster [BDS2003] 6, placed over one of the collapsing clumps in the border of the HII region, reveals that this cluster is physically associated with the nebula and gives more support to the triggered massive star formation scenario. A radio continuum data analysis indicates that the nebula is older and expands at lower velocity than typical IR Galactic bubbles.
- ID:
- ivo://CDS.VizieR/J/ApJ/649/759
- Title:
- Bubbles in the galactic disk
- Short Name:
- J/ApJ/649/759
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A visual examination of the images from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) has revealed 322 partial and closed rings that we propose represent partially or fully enclosed three-dimensional bubbles. We argue that the bubbles are primarily formed by hot young stars in massive star formation regions. We have found an average of about 1.5 bubbles per square degree. About 25% of the bubbles coincide with known radio HII regions, and about 13% enclose known star clusters. It appears that B4B9 stars (too cool to produce detectable radio HII regions) probably produce about three-quarters of the bubbles in our sample, and the remainder are produced by young OB3 stars that produce detectable radio HII regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/670/428
- Title:
- Bubbles in the galactic disk. II.
- Short Name:
- J/ApJ/670/428
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 269 mid-infrared bubbles within 10{deg} of the Galactic center from visual inspection of the Spitzer GLIMPSE II Legacy Science program images. The surface density of bubbles is ~5deg^-2^ or about 3 times that detected in longitudes |l|=10{deg}-65{deg}, because the inner 10{deg} of longitude were more thoroughly searched for small bubbles. There is a gradient in the number of bubbles with longitude with an increase of about a factor of 2 from 2{deg} to 10{deg}; this is probably the result of several factors, including decreasing diffuse background brightness, confusion, and opacity with longitude. Bubble eccentricities are typically between 0.6 and 0.8, and >50% show evidence for blowouts, which we suggest result from local density fluctuations of the ISM and/or anisotropic stellar winds and radiation fields.
