- ID:
- ivo://CDS.VizieR/J/A+A/453/1003
- Title:
- SCUBA ultracompact HII regions
- Short Name:
- J/A+A/453/1003
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a SCUBA submillimetre (450 and 850{mu}m) survey of the environment of 105 IRAS point sources, selected from the Wood and Churchwell (1989ApJS...69..831W) and Kurtz et al. (1994, Cat. J/ApJS/91/659) radio ultracompact (UC) HII region surveys. We detected a total of 155 sub-mm clumps associated with the IRAS point sources and identified three distinct types of object: ultracompact cm-wave sources that are not associated with any sub-mm emission (sub-mm quiet objects), sub-mm clumps that are associated with ultracompact cm-wave sources (radio-loud clumps); and sub-mm clumps that are not associated with any known ultracompact cm-wave sources (radio-quiet clumps). 90% of the sample of IRAS point sources were found to be associated with strong sub-mm emission. We consider the sub-mm colours, morphologies and distance-scaled fluxes of the sample of sub-mm clumps and show that the sub-mm quiet objects are unlikely to represent embedded UC HII regions unless they are located at large heliocentric distances.
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- ID:
- ivo://CDS.VizieR/J/A+A/577/A30
- Title:
- SDC335.579-0.292 6, 8, 23 and 25GHz images
- Short Name:
- J/A+A/577/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent ALMA observations identified one of the most massive star-forming cores yet observed in the Milky Way: SDC335-MM1, within the infrared dark cloud SDC335.579-0.292. Along with an accompanying core MM2, SDC335 appears to be in the early stages of its star formation process. We aim to constrain the properties of the stars forming within these two massive millimetre sources. Observations of SDC335 at 6, 8, 23 and 25GHz were made with the Australia Telescope Compact Array.We report the results of these continuum measurements, which combined with archival data, allow us to build and analyse the spectral energy distributions (SEDs) of the compact sources in SDC335.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A122
- Title:
- SDSS extremely metal-poor emission-line galaxies
- Short Name:
- J/A+A/546/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 6.5-m MMT and 3.5m APO spectrophotometry of 69 HII regions in 42 low-metallicity emission-line galaxies, selected from the data release 7 of the Sloan Digital Sky Survey to have mostly [OIII]{lambda}4959/H{beta}<~1 and [NII]{lambda}6583/H{beta}<~0.1. The electron temperature-sensitive emission line [OIII]{lambda}4363 is detected in 53 HII regions allowing a direct abundance determination. The oxygen abundance in the remaining 16 HII regions is derived using a semi-empirical method. The oxygen abundance of the galaxies in our sample ranges from 12+logO/H~7.1 to ~7.9, with 14 HII regions in 7 galaxies with 12+logO/H<=7.35. In 5 of the latter galaxies, the oxygen abundance is derived here for the first time. Including other known extremely metal-deficient emission-line galaxies from the literature, e.g. SBS 0335-052W, SBS 0335-052E and I Zw 18, we have compiled a sample of the 17 most metal-deficient (with 12+logO/H<=7.35) emission-line galaxies known in the local universe. There appears to be a metallicity floor at 12+log O/H~6.9, suggesting that the matter from which dwarf emission-line galaxies formed was pre-enriched to that level by e.g. Population III stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/153/429
- Title:
- SDSS strong emission line HII galaxies
- Short Name:
- J/ApJS/153/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first edition of the SDSS HII galaxies with Oxygen abundances Catalog (SHOC), which is a listing of strong emission-line galaxies (ELGs) from the Sloan Digital Sky Survey (SDSS, see http://www.sdss.org). We present 612 SDSS emission-line galaxies (624 separate SDSS targets in total), for which the oxygen abundances 12+log(O/H) have rms uncertainties <=0.20dex. The subsample of 263 ELGs (272 separate SDSS targets) have an uncertainty <=0.10dex, while 459 ELGs (470 separate SDSS targets) have an uncertainty <=0.15dex. The catalog includes the main parameters of all selected ELGs, the intensities and equivalent widths of hydrogen and oxygen emission lines, as well as oxygen abundances with their uncertainties. The information on the presence of Wolf-Rayet blue and/or red bumps in 109 galaxies is also included. With the use of combined g, r, i SDSS images we performed visual morphological classification of all SHOC galaxies. Four hundred sixty-one galaxies (75%) are classified as confident or probable blue compact galaxies (BCG/BCG?), 78 as irregular ones, 20 as low surface brightness galaxies (LSBG), 10 as obviously interacting, and 43 as spiral galaxies. In creating the catalog, 30 narrow-line active galactic nuclei and 69 LINERs were also identified; these are also presented apart of the main catalog.
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/768
- Title:
- SED of 180 SIMBA 1.2mm sources
- Short Name:
- J/MNRAS/392/768
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Concatenating data from the millimetre regime to the infrared, we have performed spectral energy distribution (SED) modelling for 227 of the 405 millimetre continuum sources of Hill et al. (2005, Cat. J/MNRAS/363/405) which are thought to contain young massive stars in the earliest stages of their formation. Three main parameters are extracted from the fits: temperature, mass and luminosity. The method employed was the Bayesian inference, which allows a statistically probable range of suitable values for each parameter to be drawn for each individual protostellar candidate. This is the first application of this method to massive star formation.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A36
- Title:
- Self-absorption in RCW 120
- Short Name:
- J/A+A/659/A36
- Date:
- 02 Mar 2022 07:09:25
- Publisher:
- CDS
- Description:
- Revealing the 3D dynamics of HII region bubbles and their associated molecular clouds and HI envelopes is important for developing an understanding of the longstanding problem as to how stellar feedback affects the density structure and kinematics of the different phases of the interstellar medium. We employed observations of the HII region RCW 120 in the [CII] 158um line, observed within the Stratospheric Observatory for Infrared Astronomy (SOFIA) legacy program FEEDBACK, and in the ^12^CO and ^13^CO (3-2) lines, obtained with the Atacama Pathfinder Experiment (APEX) to derive the physical properties of the gas in the photodissociation region (PDR) and in the molecular cloud. We used high angular resolution HI data from the Southern Galactic Plane Survey to quantify the physical properties of the cold atomic gas through HI self-absorption. The high spectral resolution of the heterodyne observations turns out to be essential in order to analyze the physical conditions, geometry, and overall structure of the sources. Two types of radiative transfer models were used to fit the observed [CII] and CO spectra. A line profile analysis with the 1D non-LTE radiative transfer code SimLine proves that the CO emission cannot stem from a spherically symmetric molecular cloud configuration. With a two-layer multicomponent model, we then quantified the amount of warm background and cold foreground gas. To fully exploit the spectral-spatial information in the CO spectra, a Gaussian mixture model was introduced that allows for grouping spectra into clusters with similar properties. The CO emission arises mostly from a limb-brightened, warm molecular ring, or more specifically a torus when extrapolated in 3D. There is a deficit of CO emission along the line-of-sight toward the center of the HII region which indicates that the HII region is associated with a flattened molecular cloud. Self-absorption in the CO line may hide signatures of infalling and expanding molecular gas. The [CII] emission arises from an expanding [CII] bubble and from the PDRs in the ring/torus. A significant part of [CII] emission is absorbed in a cool (~60-100K), low-density (<500cm^-3^) atomic foreground layer with a thickness of a few parsec. We propose that the RCW 120 HII region formed in a flattened, filamentary, or sheet-like, molecular cloud and is now bursting out of its parental cloud. The compressed surrounding molecular layer formed a torus around the spherically expanding HII bubble. This scenario can possibly be generalized for other HII bubbles and would explain the observed "flat" structure of molecular clouds associated with HII bubbles. We suggest that the [CII] absorption observed in many star-forming regions is at least partly caused by low-density, cool, HI-envelopes surrounding the molecular clouds.
- ID:
- ivo://CDS.VizieR/J/ApJS/229/28
- Title:
- SFiNCs: X-ray, IR and membership catalogs
- Short Name:
- J/ApJS/229/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Star Formation in Nearby Clouds (SFiNCs) project is aimed at providing a detailed study of the young stellar populations and of star cluster formation in the nearby 22 star-forming regions (SFRs) for comparison with our earlier MYStIX survey of richer, more distant clusters. As a foundation for the SFiNCs science studies, here, homogeneous data analyses of the Chandra X-ray and Spitzer mid-infrared archival SFiNCs data are described, and the resulting catalogs of over 15300 X-ray and over 1630000 mid-infrared point sources are presented. On the basis of their X-ray/infrared properties and spatial distributions, nearly 8500 point sources have been identified as probable young stellar members of the SFiNCs regions. Compared to the existing X-ray/mid-infrared publications, the SFiNCs member list increases the census of YSO members by 6%-200% for individual SFRs and by 40% for the merged sample of all 22 SFiNCs SFRs.
- ID:
- ivo://CDS.VizieR/J/A+A/344/943
- Title:
- Sh 138 BVRIJHK photometry
- Short Name:
- J/A+A/344/943
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric and spectroscopic study of the compact HII region Sh 138 and its associated stellar cluster. The positions and BVRIJHK magnitudes are obtained for more than 400 stars over a field of about 4' square centred on the HII region. Sh 138 is excited by a cluster of young massive stars. At the cluster's very centre are at least four O-B2 stars separated by less than 4". The brightest of these, both in the visible and the near infrared, exhibits a spectrum similar to those of the more massive Herbig Ae/Be stars. This star, our No. 183, is overluminous by a factor of 2.5 in the visible and four in the near IR with respect to the O9.5V star required to account for the ionization level of the HII region. However star 183's position in the J-H versus H-K diagram does not indicate a near-IR excess. We suggest that this star is a young massive object belonging to a binary or multiple system. The stellar cluster associated with Sh 138 is very reminiscent of the Orion Trapezium cluster: it is centrally peaked around several massive stars, and is dense - more than 550stars/pc^2^ at its centre. The visual extinction in the cluster varies between 5mag and more than 35mag; large variations are observed over very small scales (for example, more than 20mag over less than 4" among the central massive stars).
- ID:
- ivo://CDS.VizieR/J/BaltA/22/223
- Title:
- Sh 2-205 Vilnius photometry
- Short Name:
- J/BaltA/22/223
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of CCD photometry in the seven-color Vilnius system for 922 stars down to V~17mag in a 1.5 square degree field at the northern edge of the HII region Sh2-205, at the Perseus and Camelopardalis border. Using the intrinsic color indices and photometric reddening-free Q-parameters, two-dimensional spectral types for most stars are determined.
- ID:
- ivo://CDS.VizieR/J/ApJS/240/14
- Title:
- SIGGMA: inner galaxy data release
- Short Name:
- J/ApJS/240/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Survey of Ionized Gas of the Galaxy, Made with the Arecibo telescope (SIGGMA) provides a fully sampled view of the radio recombination line (RRL) emission from the portion of the Galactic plane visible with Arecibo. Observations use the Arecibo L-band Feed Array, which has a FWHM beam size of 3.4'. Twelve hydrogen RRLs from H163{alpha} to H174{alpha} are located within the instantaneous bandpass from 1225MHz to 1525MHz. We provide here cubes of average ("stacked") RRL emission for the inner Galaxy region 32{deg}<=l<=70{deg}, |b|<=1.5{deg}, with an angular resolution of 6'. The stacked RRL rms at 5.1km/s velocity resolution is ~0.65mJy/beam, making this the most sensitive large-scale fully sampled RRL survey extant. We use SIGGMA data to catalog 319 RRL detections in the direction of 244 known HII regions, and 108 new detections in the direction of 79 HII region candidates. We identify 11 carbon RRL emission regions, all of which are spatially coincident with known HII regions. We detect RRL emission in the direction of 14 of the 32 supernova remnants (SNRs) found in the survey area. This RRL emission frequently has the same morphology as the SNRs. The RRL velocities give kinematic distances in agreement with those found in the literature, indicating that RRLs may provide an additional tool to constrain distances to SNRs. Finally, we analyze the two bright star-forming complexes: W49 and W51. We discuss the possible origins of the RRL emission in directions of SNRs W49B and W51C.
