- ID:
- ivo://CDS.VizieR/J/A+A/592/A54
- Title:
- Combined ArTeMiS+SPIRE 350um image of NGC6334
- Short Name:
- J/A+A/592/A54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Herschel observations of nearby molecular clouds suggest that interstellar filaments and prestellar cores represent two fundamental steps in the star formation process. The observations support a picture of low-mass star formation according to which filaments of ~0.1pc width form first in the cold interstellar medium, probably as a result of large-scale compression of interstellar matter by supersonic turbulent flows, and then prestellar cores arise from gravitational fragmentation of the densest filaments. Whether this scenario also applies to regions of high-mass star formation is an open question, in part because the resolution of Herschel is insufficient to resolve the inner width of filaments in the nearest regions of massive star formation. In an effort to characterize the inner width of filaments in high-mass star-forming regions, we imaged the central part of the NGC 6334 complex at a resolution higher by a factor of >3 than Herschel at 350microns. We used the large-format bolometer camera ArTeMiS on the APEX telescope and combined the high-resolution ArTeMiS data at 350microns with Herschel/HOBYS data at 70-500microns to ensure good sensitivity to a broad range of spatial scales. This allowed us to study the structure of the main narrow filament of the complex with a resolution of 8" or <0.07pc at d~1.7kpc. Our study confirms that this filament is a very dense, massive linear structure with a line mass ranging from ~500M_{sun}_/pc to ~2000M_{sun}_/pc over nearly 10pc. It also demonstrates for the first time that its inner width remains as narrow as W~0.15+/-0.05pc all along the filament length, within a factor of <2 of the characteristic 0.1pc value found with Herschel for lower-mass filaments in the Gould Belt. While it is not completely clear whether the NGC 6334 filament will form massive stars in the future, it is two to three orders of magnitude denser than the majority of filaments observed in Gould Belt clouds, and has a very similar inner width. This points to a common physical mechanism for setting the filament width and suggests that some important structural properties of nearby clouds also hold in high-mass star-forming regions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/563/A39
- Title:
- Cometary HII regions of DR21
- Short Name:
- J/A+A/563/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep Very Large Array H66{alpha} radio recombination line (RRL) observations of the two cometary HII regions in DR 21. With these sensitive data, we test the "hybrid" bow shock/champagne flow model previously proposed for the DR 21 HII regions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/391/1527
- Title:
- Compact HII regions IR photometry
- Short Name:
- J/MNRAS/391/1527
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 3.6, 4.5, 5.8 and 8.0um photometry and mapping for 58 compact HII regions identified using the Spitzer Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE). These are used to investigate trends in the colours, magnitudes and structures of the sources, together with spatial variations in flux ratio. It is concluded that most of the sources are remarkably similar, and have comparable variations in flux ratio as a function of position within the shells, together with very narrowly defined ranges of colour index.
- ID:
- ivo://CDS.VizieR/J/ApJS/80/211
- Title:
- Compact Radio Sources Near the Galactic Plane
- Short Name:
- J/ApJS/80/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of the extension of the 20-cm Galactic-plane survey reported by Zoonematkermani to Galactic latitudes of +/-1.8{deg} over the central region of the Milky Way are reported. A total of 1457 discrete radio sources down to flux densities of less than about 5mJy, and 95% completion is achieved at 20mJy. A detailed comparison of all radio sources from the survey in this longitude range with the IRAS Point Source Catalog provides classification for 13% of the objects, including 159 compact H II regions, and nearly 100 planetary nebulae, over 70 of which are identified. The identity of the remaining radio sources is discussed.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/49
- Title:
- Constraining the epoch of reionization
- Short Name:
- J/ApJ/834/49
- Date:
- 09 Feb 2022 14:54:48
- Publisher:
- CDS
- Description:
- We combine observational data on a dozen independent cosmic properties at high-z with the information on reionization drawn from the spectra of distant luminous sources and the cosmic microwave background (CMB) to constrain the interconnected evolution of galaxies and the intergalactic medium since the dark ages. The only acceptable solutions are concentrated in two narrow sets. In one of them reionization proceeds in two phases: a first one driven by Population III stars, completed at z~10, and after a short recombination period a second one driven by normal galaxies, completed at z~6. In the other set both kinds of sources work in parallel until full reionization at z~6. The best solution with double reionization gives excellent fits to all the observed cosmic histories, but the CMB optical depth is 3{sigma} larger than the recent estimate from the Planck data. Alternatively, the best solution with single reionization gives less good fits to the observed star formation rate density and cold gas mass density histories, but the CMB optical depth is consistent with that estimate. We make several predictions, testable with future observations, that should discriminate between the two reionization scenarios. As a byproduct our models provide a natural explanation to some characteristic features of the cosmic properties at high-z, as well as to the origin of globular clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/309/581
- Title:
- CO observations of clouds in IC 1396 region
- Short Name:
- J/A+A/309/581
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- ^12^CO and ^13^CO (1-0) parameters are observed for selected clouds and cloud cores (or part of clouds) in the region of IC 1396
- ID:
- ivo://CDS.VizieR/VII/50
- Title:
- CO Radial Velocities Toward Galactic H II Regions
- Short Name:
- VII/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains machine-readable versions of the "Catalog of CO Radial Velocities Toward Galactic HII Regions" (Blitz et al. 1982) and the "Catalog of Carbon Monoxide Observations of Southern Hemisphere HII Regions" (Gillespie et al. 1977) in two separate files. The former is a catalog of 242 molecular cloud complexes that are associated with optical HII regions and includes source names, coordinates, CO radial velocities, antenna temperatures and full width at half-maximum at the position of the strongest CO emission, references for the observations, distances to the stars exciting the HII regions, and optical diameters of the HII regions. The latter is the first CO survey of the southern sky; it was made using the Anglo-Australian 3.9-m optical telescope at 115GHz (2.6-mm wavelength) with a hot-electron bolometer receiver located at the Coude focus. The data were collected during two observing periods (September 1975, April 1976) and include designations, coordinates, median values for the velocities, and distances to the stars exciting the HII regions.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A99
- Title:
- Cores in HII regions parameters
- Short Name:
- J/A+A/611/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-mass stars form in much richer environments than those associated with isolated low-mass stars, and once they reach a certain mass, produce ionised (HII) regions. The formation of these pockets of ionised gas are unique to the formation of high-mass stars (M>8M_{sun}_), and present an excellent opportunity to study the final stages of accretion, which could include accretion through the HII region itself. This study of the dynamics of the gas on both sides of these ionisation boundaries in very young HII regions aims to quantify the relationship between the HII regions and their immediate environments. We present high-resolution (~0.5") ALMA observations of nine HII regions selected from the Red MSX Source (RMS, Lumsden et al., Cat. J/ApJS/208/11) survey with compact radio emission and bolometric luminosities greater than 10^4^L_{sun}_. We focus on the initial presentation of the data, including initial results from the radio recombination line H29{alpha} some complementary molecules, and the 256GHz continuum emission.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A103
- Title:
- CORNISH project. III. UCHII region catalogue
- Short Name:
- J/A+A/615/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of 239 ultra-compact HII regions (UCHIIs) found in the CORNISH survey at 5GHz and 1.5-arcsec resolution in the region 10{deg}<l<65{deg}, |b|<1{deg} is presented. This is the largest complete and well-selected sample of UCHIIs to date and provides the opportunity to explore the global and individual properties of this key state in massive star formation at multiple wavelengths. The nature of the candidates was validated, based on observational properties and calculated spectral indices, and the analysis is presented in this work. The physical sizes, luminosities and other physical properties were computed by utilising literature distances or calculating the distances whenever a value was not available. The near- and mid-infrared extended source fluxes were measured and the extinctions towards the UCHIIs were computed. The new results were combined with available data at longer wavelengths and the spectral energy distributions (SEDs) were reconstructed for 177 UCHIIs. The bolometric luminosities obtained from SED fitting are presented. By comparing the radio flux densities to previous observational epochs, we find about 5% of the sources appear to be time variable. This first high-resolution area survey of the Galactic plane shows that the total number of UCHIIs in the Galaxy is ~750 - a factor of 3-4 fewer than found in previous large area radio surveys. It will form the basis for future tests of models of massive star formation.
- ID:
- ivo://CDS.VizieR/J/ApJS/196/18
- Title:
- CO survey of galactic molecular clouds. II.
- Short Name:
- J/ApJS/196/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present fully sampled 38" resolution maps of the CO and ^13^CO J=2-1 lines in the molecular clouds toward the HII region complex W3. The maps cover a 2.0{deg}x1.67{deg} section of the galactic plane and span -70 to -20km/s (LSR) in velocity with a resolution of ~1.3km/s. The velocity range of the images includes all the gas in the Perseus spiral arm. We also present maps of CO J=3-2 emission for a 0.5{deg}x0.33{deg} area containing the HII regions W3 Main and W3(OH). The J=3-2 maps have velocity resolution of 0.87km/s and 24" angular resolution. Color figures display the peak line brightness temperature, the velocity-integrated intensity, and velocity channel maps for all three lines, and also the (CO/^13^CO) J=2-1 line intensity ratios as a function of velocity. The line intensity image cubes are made available in standard FITS format as electronically readable files. We compare our molecular line maps with the 1.1mm continuum image from the BOLOCAM Galactic Plane Survey (BGPS). From our ^13^CO image cube, we derive kinematic information for the 65 BGPS sources in the mapped field, in the form of Gaussian component fits.
