- ID:
- ivo://CDS.VizieR/J/ApJS/191/232
- Title:
- CO survey of W51 molecular cloud
- Short Name:
- J/ApJS/191/232
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 38" resolution maps of the CO and ^13^COJ=2-1 lines in the molecular clouds toward the HII region complex W51. The maps cover a 1.25x1{deg} section of the galactic plane and span +30 to +85km/s (LSR) in velocity. The spectral resolution is ~1.3km/s. The velocity range of the images includes all the gas in the Sagittarius spiral arm. Color figures display the peak line brightness temperature, the velocity-integrated intensity, and 2km/s channel-averaged maps for both isotopologs, and also the CO/^13^COJ=2-1 line intensity ratio as a function of velocity. The CO and ^13^CO line intensity image cubes are made available in standard FITS format as electronically readable tables. We compare our molecular line maps with the 1.1mm continuum image from the BOLOCAM Galactic Plane Survey (BGPS; Aguirre et al. 2011ApJS..192....4A; Rosolowsky et al. 2010, Cat. J/ApJS/188/123). From our ^13^CO image cube, we derive kinematic information for the 99 BGPS sources in the mapped field in the form of Gaussian component fits. The integrated ^13^CO line intensity and the 1.1mm source flux density show only a modest degree of correlation for the 99 sources, likely due to a range of dust and gas physical conditions within the sources. However, the 1.1mm continuum surface brightness and the integrated ^13^CO line intensity for small regions containing single BGPS sources and molecular clouds show very good correlations in many cases.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/417/107
- Title:
- CO velocities in southern HII regions
- Short Name:
- J/A+A/417/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ^12^CO(1-0), ^12^CO(2-1) and/or ^13^CO(1-0) observations in the direction of HII regions located in the southern Galactic plane. The CO lines have been fitted with gaussian lines. For each direction (indicated by the galactic coordinates put in the source identification) we detect several components. The parameter, central position, line width and intensity of every component are listed in tables 2 and 3. In addition, we indicate, in the last two columns the velocity from radio and H{alpha} data of the pointed HII region.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A158
- Title:
- Data cubes of observed species toward Messier 8
- Short Name:
- J/A+A/615/A158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Messier 8 (M8) is one of the brightest HII regions in the sky. We collected an extensive dataset comprising multiple submillimeter spectral lines from neutral and ionized carbon and from CO. Based on this dataset, we aim to understand the morphology of M8 and that of its associated photodissociation region (PDR) and to carry out a quantitative analysis of the physical conditions of these regions such as kinetic temperatures and volume densities. We used the Stratospheric Observatory For Infrared Astronomy (SOFIA), the Atacama Pathfinder Experiment (APEX) 12m, and the Institut de Radioastronomie Millimetrique (IRAM) 30m telescopes to perform a comprehensive imaging survey of the emission from the fine structure lines of CII and CI and multiple rotational transitions of carbon monoxide (CO) isotopologs within 1.3x1.3pc around the dominant Herschel 36 (Her 36) system, which is composed of at least three massive stars. To further explore the morphology of the region, we compared archival infrared, optical, and radio images of the nebula with our newly obtained fine structure line and CO data, and in particular with the velocity information these data provide. We performed a quantitative analysis, using both LTE and non-LTE methods to determine the abundances of some of the observed species, kinetic temperatures, and volume densities. Bright CO, CII and CI emission have been found toward the HII region and the PDR in M8. Our analysis places the bulk of the molecular material in the background of the nebulosity illuminated by the bright stellar systems Her 36 and 9 Sagitarii. Since the emission from all observed atomic and molecular tracers peaks at or close to the position of Her 36, we conclude that the star is still physically close to its natal dense cloud core and heats it. A veil of warm gas moves away from Her 36 toward the Sun and its associated dust contributes to the foreground extinction in the region. One of the most prominent star forming regions in M8, the Hourglass Nebula, is particularly bright due to cracks in this veil close to Her 36. We obtain H_2_ densities ranging from ~10^4^-10^6^cm^-3^ and kinetic temperatures of 100-150K in the bright PDR caused by Her 36 using radiative transfer modeling of various transitions of CO isotopologs.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/23
- Title:
- Deep Chandra obs. of the giant HII region N11 in LMC
- Short Name:
- J/ApJS/213/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A very sensitive X-ray investigation of the giant H II region N11 in the Large Megallanic Cloud was performed using the Chandra X-ray Observatory. The 300ks observation reveals X-ray sources with luminosities down to 10^32^erg/s, increasing the number of known point sources in the field by more than a factor of five. Among these detections are 13 massive stars (3 compact groups of massive stars, 9 O stars, and one early B star) with log (L_X_/L_BOL_)~-6.5 to -7, which may suggest that they are highly magnetic or colliding-wind systems. On the other hand, the stacked signal for regions corresponding to undetected O stars yields log (L_X_/L_BOL_)~-7.3, i.e., an emission level comparable to similar Galactic stars despite the lower metallicity. Other point sources coincide with 11 foreground stars, 6 late-B/A stars in N11, and many background objects. This observation also uncovers the extent and detailed spatial properties of the soft, diffuse emission regions, but the presence of some hotter plasma in their spectra suggests contamination by the unresolved stellar population.
- ID:
- ivo://CDS.VizieR/J/ApJ/599/1006
- Title:
- DEEP Groth Strip Survey. VII.
- Short Name:
- J/ApJ/599/1006
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using spectroscopic data from the Deep Extragalactic Evolutionary Probe Groth Strip Survey (DGSS), we analyze the gas-phase oxygen abundances in the warm ionized medium for 64 emission-line field galaxies in the redshift range 0.26<z<0.82. These galaxies comprise a small subset selected from among 693 objects in the DGSS. They are chosen for chemical analysis by virtue of having the strongest emission lines. Oxygen abundances relative to hydrogen are in the range 8.4<12+log(O/H)<9.0 with typical internal plus systematic measurement uncertainties of 0.17dex. The 64 DGSS galaxies collectively exhibit an increase in metallicity with B-band luminosity, i.e., an L-Z relation like that seen among local galaxies. Using the DGSS sample and local galaxy samples for comparison, we searched for a "second parameter" that might explain some of the dispersion seen in the L-Z relation. Parameters such as galaxy color, emission-line equivalent width, and effective radius were explored but found to be uncorrelated with residuals from the mean L-Z relation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/391/1384
- Title:
- Deep MERLIN 5GHz radio sources in M82
- Short Name:
- J/MNRAS/391/1384
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of an extremely deep, 8-d long observation of the central kpc of the nearby starburst galaxy M82 using Multi-Element Radio Linked Interferometer Network (MERLIN) at 5GHz are presented. The 17{mu}Jy/beam rms noise level in the naturally weighted image makes it the most sensitive high-resolution radio image of M82 made to date. Over 50 discrete sources are detected, the majority of which are supernova remnants, but with 13 identified as H ii regions. Sizes, flux densities and radio brightnesses are given for all of the detected sources, which are all well resolved with a majority showing shell or partial shell structures. Those sources within the sample which are supernova remnants have diameters ranging from 0.3 to 6.7pc, with a mean size of 2.9pc.
- ID:
- ivo://CDS.VizieR/J/ApJ/891/81
- Title:
- Deep optical and infrared photometry of Sh2-305
- Short Name:
- J/ApJ/891/81
- Date:
- 17 Jan 2022 00:38:10
- Publisher:
- CDS
- Description:
- Using our deep optical and near-infrared photometry along with multiwavelength archival data, we here present a detailed study of the Galactic HII region Sh 2-305 to understand the star/star-cluster formation. On the basis of excess infrared emission, we have identified 116 young stellar objects (YSOs) within a field of view of ~18.5'x18.5' around Sh 2-305. The average age, mass, and extinction (AV) for this sample of YSOs are 1.8Myr, 2.9M_{sun}_, and 7.1mag, respectively. The density distribution of stellar sources along with minimal spanning tree calculations on the location of YSOs reveals at least three stellar subclusterings in Sh 2-305. One cluster is seen toward the center (i.e., Mayer 3), while the other two are distributed toward the north and south directions. Two massive O-type stars (VM2 and VM4; ages ~5Myr) are located at the center of the Sh 2-305 HII region. The analysis of the infrared and radio maps traces the photon-dominant regions (PDRs) in Sh 2-305. The association of the younger generation of stars with the PDRs is also investigated in Sh2-305. This result suggests that these two massive stars might have influenced the star formation history in Sh 2-305. This argument is also supported by the calculation of various pressures driven by massive stars, the slope of the mass function/K-band luminosity function, star formation efficiency, fraction of Class I sources, and mass of the dense gas toward the subclusterings in Sh 2-305.
- ID:
- ivo://CDS.VizieR/J/other/RMxAA/45.261
- Title:
- Diffuse ionized gas database DIGEDA
- Short Name:
- J/other/RMxAA/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of the Diffuse Ionized Gas (DIG) have progressed without providing so far any strict criterion to distinguish DIGs from HII regions. In this work, we compile the emission line measurements of 29 galaxies that are available in the scientific literature, thereby setting up the first DIG database DIGEDA. Making use of this database, we proceeded to analyze global properties of the DIG using the [NII]6583/Halpha, [OI]6300/Halpha, [OIII]5007/Hbeta and [SII]6716/Halpha lines ratios, including the Halpha emission measure. This analysis leads us to conclude that the [NII]/Halpha ratio provides an objective criterion for distinguishing whether an emission region is DIG or an HII region, while the EM(Halpha) is a useful quantity only when the galaxies are considered individually. Finally, we find that the emission regions of Irr galaxies classified as DIG in the literature appear in fact to be much more similar to HII regions than to the DIGs of spiral galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A95
- Title:
- Diffuse ionized gas in the Antennae galaxy
- Short Name:
- J/A+A/611/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Antennae galaxy (NGC 4038/39) is the closest major interacting galaxy system and is therefore often studied as a merger prototype. We present the first comprehensive integral field spectroscopic dataset of this system, observed with the MUSE instrument at the ESO VLT. We cover the two regions in this system which exhibit recent star formation: the central galaxy interaction and a region near the tip of the southern tidal tail. In these fields, we detect HII regions and diffuse ionized gas to unprecedented depth. About 15% of the ionized gas was undetected by previous observing campaigns. This newly detected faint ionized gas is visible everywhere around the central merger, and shows filamentary structure. We estimate diffuse gas fractions of about 60% in the central field and 10% in the southern region. We are able to show that the southern region contains a significantly different population of HII regions, showing fainter luminosities. By comparing HII region luminosities with the HST catalog of young star clusters in the central field, we estimate that there is enough Lyman-continuum leakage in the merger to explain the amount of diffuse ionized gas that we detect. We compare the Lyman-continuum escape fraction of each HII region against emission line ratios that are sensitive to the ionization parameter. While we find no systematic trend between these properties, the most extreme line ratios seem to be strong indicators of density bounded ionization. Extrapolating the Lyman-continuum escape fractions to the southern region, we conclude that simply from the comparison of the young stellar populations to the ionized gas there is no need to invoke other ionization mechanisms than Lyman-continuum leaking HII regions for the diffuse ionized gas in the Antennae.
- ID:
- ivo://CDS.VizieR/J/ApJ/690/706
- Title:
- Distances of Galactic HII regions
- Short Name:
- J/ApJ/690/706
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We resolve the kinematic distance ambiguity for 266 inner Galaxy HII regions out of a sample of 291 using existing HI and ^13^CO sky surveys. Our sample contains all HII regions with measured radio recombination line emission over the extent of the ^13^CO Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (18<l<55{deg} and |b|<1) and contains ultra compact (UC), compact, and diffuse HII regions. We use two methods for resolving the distance ambiguity for each HII region: HI emission/absorption (HI E/A) and HI self-absorption (HI SA).
