- ID:
- ivo://CDS.VizieR/J/A+A/569/A36
- Title:
- G53.541-0.011 ^12^CO and ^13^CO data cubes
- Short Name:
- J/A+A/569/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate how a large-scale infrared bubble centered at l=53.9{deg} and b=0.2{deg} forms, and to study if star formation is taking place at the periphery of the bubble, we performed a multiwavelength study. Using the data from the Galactic Ring Survey (GRS) and Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), we performed a study of a large-scale infrared bubble with a size of about 16pc at a distance of 2.0kpc. We present the ^12^CO J=1-0, ^13^CO J=1-0, and C^18^O J=1-0 observations of HII region G53.54-0.01 (Sh2-82) obtained at the Purple Mountain Observation (PMO) 13.7m radio telescope to investigate the detailed distribution of associated molecular material. In addition, we also used radiorecombination line and VLA data. To select young stellar objects (YSOs) consistent with this region, we used the GLIMPSE I catalog.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/488/224
- Title:
- 4.85 GHz fluxes of H II regions
- Short Name:
- J/ApJ/488/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an all-sky flux catalog of 760 H II regions with angular sizes ranging up to 10' at 4.85GHz. The data were compiled in a self-consistent manner from existing images of the Green Bank and Parkes-MIT-NRAO 4.85GHz radio continuum surveys. Nearly 35% of these H II regions have fluxes measured from these surveys for the first time. We compared our results to the previously published source catalogs which fit the same data. The new flux measurements agree within 5%-7% of these values and fall well within the formal errors. The diameters fall within 16% of the previously published fits to the same data, within the formal uncertainties of these values.
- ID:
- ivo://CDS.VizieR/J/ApJS/245/12
- Title:
- 6.7GHz methanol masers & RRLs in MSX regions
- Short Name:
- J/ApJS/245/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a systematic survey of a 6.7GHz Class II methanol maser toward a sample of 448 sources selected from the Red Midcourse Space Experiment Source catalog. These sample sources are composed of high-mass star-forming region (HMSFR) candidates and have been studied as tracers of HMSFRs, such as water masers or radio continuum emission of ultracompact HII region. The survey was conducted using the Shanghai Tianma Radio Telescope. Through the observations, we simultaneously studied the 4.7 and 6.0GHz excited-state interstellar hydroxyl (OH) maser lines and 10 hydrogen radio recombination lines (RRLs) in the C band. In total, we detected 6.7GHz methanol masers and RRLs from 102 and 116 sources, respectively. In addition, 4, 3, and 10 sources exhibit OH masers at 4765.56, 6030.75, and 6035.09MHz transitions, respectively. Through the survey, we identified four new 6.7GHz methanol maser sources and three new excited-state OH maser sources (one at 4750MHz and two at 6035MHz). The statistical analysis demonstrated that there is a positive correlation of luminosity between 6.7GHz methanol masers and RRLs. A good correlation of integrated luminosity between radio continuum emission and the 6.7GHz methanol masers is presented with respect to the RRL emission sources. The average of the integrated luminosities of the RRLs in the sources with 6.7GHz masers is greater than those without the 6.7GHz masers; similarly, the average of integrated luminosities of the 6.7GHz methanol masers in the sources with RRLs is greater than those without the RRLs. Moreover, we found that the averages of the emission measure and electron temperature of HII regions associated with 6.7GHz methanol masers are larger than those without the 6.7GHz methanol masers. This suggests that the masers are most likely produced in high gas density and luminous regions with brighter RRLs and higher radio continuum emission.
- ID:
- ivo://CDS.VizieR/J/A+A/413/233
- Title:
- 12.2 GHz methanol survey
- Short Name:
- J/A+A/413/233
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of 12.2GHz methanol maser survey done with the Torun 32 meter radio telescope. We examined 261 star forming sites, known as containing 6.7GHz maser emission sources. The survey resulted in 49 sources with maser line detection, with 21 previously unknown emissions. All detected 12.2GHz masers have been observed at 6.7GHz transition. Only one 12.2GHz source has no 6.7GHz counterpart. We compared basic spectral line properties at both transitions. In a few cases we observed absorption features and emitting counterparts in the other monitored frequency, at the same velocity.
- ID:
- ivo://CDS.VizieR/J/ApJ/777/157
- Title:
- 90GHz obs. of high-mass star-forming regions
- Short Name:
- J/ApJ/777/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical changes of high-mass star-forming regions provide a potential method for classifying their evolutionary stages and, ultimately, ages. In this study, we search for correlations between molecular abundances and the evolutionary stages of dense molecular clumps associated with high-mass star formation. We use the molecular line maps from Year 1 of the Millimetre Astronomy Legacy Team 90GHz (MALT90) Survey. The survey mapped several hundred individual star-forming clumps chosen from the ATLASGAL survey to span the complete range of evolution, from prestellar to protostellar to H II regions. The evolutionary stage of each clump is classified using the Spitzer GLIMPSE/MIPSGAL mid-IR surveys. Where possible, we determine the dust temperatures and H_2_ column densities for each clump from Herschel/Hi-GAL continuum data. From MALT90 data, we measure the integrated intensities of the N_2_H^+^, HCO^+^, HCN and HNC(1-0) lines, and derive the column densities and abundances of N_2_H^+^ and HCO^+^. The Herschel dust temperatures increase as a function of the IR-based Spitzer evolutionary classification scheme, with the youngest clumps being the coldest, which gives confidence that this classification method provides a reliable way to assign evolutionary stages to clumps. Both N_2_H^+^ and HCO^+^ abundances increase as a function of evolutionary stage, whereas the N_2_H^+^(1-0) to HCO^+^(1-0) integrated intensity ratios show no discernable trend. The HCN(1-0) to HNC(1-0) integrated intensity ratios show marginal evidence of an increase as the clumps evolve.
- ID:
- ivo://CDS.VizieR/J/AZh/62/229
- Title:
- Giant H II region Ratan-600 observations
- Short Name:
- J/AZh/62/229
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of observations of a giant H II region, situated at the longitudes 4-10deg, at the wavelength 7.6cm are presented. A catalogue has been compiled containing 63 sources for which the positions, flux densities, and angular dimensions have been determined. Forty-four objects with the fluxes P<1Jy and having small angular sizes have been detected. The radio brightness distribution of the background component of the galactic radio emission has been obtained. A weak background extended by more than 2deg in the galactic latitude has been registered. It is shown that the detected weak objects represent a more high-latitude population than the strong galactic sources and are probably associated with the weak extended background.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1739
- Title:
- Giant HII regions BOND abundances
- Short Name:
- J/MNRAS/460/1739
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Bayesian oxygen and nitrogen abundance determinations (bond) method. bond is a Bayesian code (available at: http://bond.ufsc.br) to simultaneously derive oxygen and nitrogen abundances in giant HII regions. It compares observed emission lines to a grid of photoionization models without assuming any relation between O/H and N/O. Our grid spans a wide range in O/H, N/O and ionization parameter U, and covers different starburst ages and nebular geometries. Varying starburst ages accounts for variations in the ionizing radiation field hardness, which arise due to the ageing of HII regions or the stochastic sampling of the initial mass function. All previous approaches assume a strict relation between the ionizing field and metallicity. The other novelty is extracting information on the nebular physics from semistrong emission lines. While strong lines ratios alone ([OIII]/H{beta}, [OII]/H{beta} and [NII]/H{beta}) lead to multiple O/H solutions, the simultaneous use of [ArIII]/[NeIII] allows one to decide whether an HII region is of high or low metallicity. Adding HeI/H{beta} pins down the hardness of the radiation field. We apply our method to HII regions and blue compact dwarf galaxies, and find that the resulting N/O versus O/H relation is as scattered as the one obtained from the temperature-based method. As in previous strong-line methods calibrated on photoionization models, the bond O/H values are generally higher than temperature-based ones, which might indicate the presence of temperature fluctuations or kappa distributions in real nebulae, or a too soft ionizing radiation field in the models.
- ID:
- ivo://CDS.VizieR/J/ApJS/212/2
- Title:
- Giant molecular clouds in the 4th Galactic quadrant
- Short Name:
- J/ApJS/212/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Columbia University-Universidad de Chile CO Survey of the southern Milky Way is used to separate the CO(1-0) emission of the fourth Galactic quadrant within the solar circle into its dominant components, giant molecular clouds (GMCs). After the subtraction of an axisymmetric model of the CO background emission in the inner southern Galaxy, 92 GMCs are identified, and for 87 of them the twofold distance ambiguity is solved. Their total molecular mass is M(H_2_)=1.14+/-0.05x10^8^M_{sun}_, accounting for around 40% of the molecular mass estimated from an axisymmetric analysis of the H_2_ volume density in the Galactic disk, M(H_2_)_disk_=3.03x10^8^M_{sun}_. The large-scale spiral structure in the southern Galaxy, within the solar circle, is traced by the GMCs in our catalog; three spiral arm segments, the Centaurus, Norma, and 3 kpc expanding arm, are analyzed. After fitting a logarithmic spiral arm model to the arms, tangent directions at 310{deg}, 330{deg}, and 338{deg}, respectively, are found, consistent with previous values from the literature. A complete CS(2-1) survey toward IRAS point-like sources with far-IR colors characteristic of ultracompact H II regions is used to estimate the massive star formation rate per unit H_2_ mass (MSFR) and the massive star formation efficiency ({epsilon}) for GMCs. The average MSFR for GMCs is 0.41+/-0.06L_{sun}_/M_{sun}_, and for the most massive clouds in the Norma arm it is 0.58+/-0.09L_{sun}_/M_{sun}_. Massive star formation efficiencies of GMCs are, on average, 3% of their available molecular mass.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A131
- Title:
- Giant molecular filaments in the Milky Way
- Short Name:
- J/A+A/590/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Filamentary structures are common morphological features of the cold, molecular interstellar medium (ISM). Recent studies have discovered massive, hundred-parsec-scale filaments that may be connected to the large-scale, Galactic spiral arm structure. Addressing the nature of these giant molecular filaments (GMFs) requires a census of their occurrence and properties. We perform a systematic search of GMFs in the fourth Galactic quadrant and determine their basic physical properties. We perform a systematic search of GMFs in the fourth Galactic quadrant and determine their basic physical properties. Methods. We identify GMFs based on their dust extinction signatures in the near- and mid-infrared and the velocity structure probed by ^13^CO line emission. We use the ^13^CO line emission and ATLASGAL dust emission data to estimate the total and dense gas masses of the GMFs. We combine our sample with an earlier sample from literature and study the Galactic environment of the GMFs.
- ID:
- ivo://CDS.VizieR/J/A+A/653/A108
- Title:
- Globules and pillars in Cygnus X
- Short Name:
- J/A+A/653/A108
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- IRAS 20319+3958 in Cygnus X South is a rare example of a free-floating globule (mass ~240M_{sun}_, length ~1.5pc) with an internal HII region created by the stellar feedback of embedded intermediate-mass stars, in particular, one Herbig Be star. In Schneider et al. (2012A&A...542L..18S) and Djupvik et al. (2017A&A...599A..37D, Cat. J/A+A/599/A37), we proposed that the emission of the far-infrared (FIR) lines of [CII] at 158um and [OI] at 145um in the globule head are mostly due to an internal photodissociation region (PDR). Here, we present a Herschel/HIFI [CII] 158um map of the whole globule and a large set of other FIR lines (mid-to high-J CO lines observed with Herschel/PACS and SPIRE, the [OI] 63um line and the ^12^CO 16->15 line observed with upGREAT on SOFIA), covering the globule head and partly a position in the tail. The [CII] map revealed that the whole globule is probably rotating. Highly collimated, high-velocity [CII] emission is detected close to the Herbig Be star. We performed a PDR analysis using the KOSMA-{tau}PDR code for one position in the head and one in the tail. The observed FIR lines in the head can be reproduced with a two-component model: an extended, non-clumpy outer PDR shell and a clumpy, dense, and thin inner PDR layer, representing the interface between the HII region cavity and the external PDR. The modelled internal UV field of ~2500Go is similar to what we obtained from the Herschel FIR fluxes, but lower than what we estimated from the census of the embedded stars. External illumination from the ~30pc distant Cyg OB2 cluster, producing an UV field of ~150-600Go as an upper limit, is responsible for most of the [CII] emission. For the tail, we modelled the emission with a non-clumpy component, exposed to a UV-field of around 140Go.
