- ID:
- ivo://CDS.VizieR/J/ApJ/706/727
- Title:
- Distance and mass of Infrared Dark Clouds
- Short Name:
- J/ApJ/706/727
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared Dark Clouds (IRDCs) are dark clouds seen in silhouette in mid-infrared surveys. They are thought to be the birthplace of massive stars, yet remarkably little information exists on the properties of the population as a whole (e.g., mass spectrum, spatial distribution). Genetic forward modeling is used along with the Two Micron All Sky Survey and the Besancon Galactic model to deduce the three-dimensional distribution of interstellar extinction toward previously identified IRDC candidates. This derived dust distribution can then be used to determine the distance and mass of IRDCs, independently of kinematic models of the Milky Way. Along a line of sight that crosses an IRDC, the extinction is seen to rise sharply at the distance of the cloud. Assuming a dust-to-gas ratio, the total mass of the cloud can be estimated. The method has been successfully applied to 1259 IRDCs, including over 1000 for which no distance or mass estimate currently exists. The IRDCs are seen to lie preferentially along the spiral arms and in the molecular ring of the Milky Way, reinforcing the idea that they are the birthplace of massive stars. Also, their mass spectrum is seen to follow a power law with an index of -1.75+/-0.06, steeper than giant molecular clouds (GMCs) in the inner Galaxy but comparable to clumps in GMCs. This slope suggests that the IRDCs detected using the present method are not gravitationally bound, but are rather the result of density fluctuations induced by turbulence.
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- ID:
- ivo://CDS.VizieR/J/A+A/646/A74
- Title:
- Distance of HiGAL sources
- Short Name:
- J/A+A/646/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Distances are key to determine the physical properties of sources. In the Galaxy, large (>10000) homogeneous samples of sources for which distance are available, covering the whole galactic distance range, are still missing. Here we present a catalog of velocity and distance for a large sample (>100000) of Hi-GAL compact sources. We develop a fully automatic Python-package to extract the velocity and determine the distance. To assign a velocity to a Hi-GAL compact source, the code uses all the available spectroscopic data complemented by a morphological analysis. Once the velocity is determined, if no stellar or maser parallax distance is known, the kinematic distance is calculated and the distance ambiguity (for sources located inner the Solar circle) is solved with the HII self-absorption method or from distance-extinction data. Among the 150223 compact sources of the Hi-GAL catalog, we obtained a distance for for 124069 sources for the 5-sigma catalog (and 128351 sources for the 3-sigma catalog), where sigma represents the noise level of each molecular spectrum used for the lines detection made at 5-sigma and 3-sigma, to produce the respective catalog.
- ID:
- ivo://CDS.VizieR/J/ApJS/136/463
- Title:
- Distances and metallicities of HVCs and IVCs
- Short Name:
- J/ApJS/136/463
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A table is presented that summarizes published absorption line measurements for the high- and intermediate-velocity clouds (HVCs and IVCs). New values are derived for N(HI) in the direction of observed probes, in order to arrive at reliable abundances and abundance limits (the HI data are described in Paper II, Wakker et al., 2001ApJS..136..537W). Distances to stellar probes are revisited and calculated consistently, in order to derive distance brackets or limits for many of the clouds, taking care to properly interpret nondetections.
- ID:
- ivo://CDS.VizieR/J/ApJS/256/46
- Title:
- Distances & color excesses of high gal. mol. clouds
- Short Name:
- J/ApJS/256/46
- Date:
- 03 Mar 2022 14:08:03
- Publisher:
- CDS
- Description:
- Based on the accurate color excess E_GBP,GRP_ of more than 4 million stars and the E_NUV,GBP_ of more than 1 million stars from Paper I (Sun+, 2021ApJS..254...38S), the distance and extinction of the molecular clouds (MCs) in the Magnani-Blitz-Mundy (MBM; 1985ApJ...295..402M) catalog at |b|>20{deg} are studied in combination with the distance measurement of Gaia/EDR3. The distance, as well as the color excess, is determined for 66 MCs. The color excess ratio E_NUV,GBP_/E_GBP,GRP_ is derived for 39 of them, which is obviously larger and implies more small particles at smaller extinction. In addition, the scale height of the dust disk is found to be about 100 pc and becomes large at the anticenter direction due to the disk flaring.
- ID:
- ivo://CDS.VizieR/J/MNRAS/422/3178
- Title:
- Distances of 793 BGPS sources
- Short Name:
- J/MNRAS/422/3178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By positional matching to the catalogue of Galactic Ring Survey molecular clouds, we have derived distances to 793 Bolocam Galactic Plane Survey (BGPS) sources out of a possible 806 located within the region defined by Galactic longitudes l=28.5{deg}-31.5{deg} and latitudes |b|<=1{deg}. This section of the Galactic plane contains several major features of Galactic structure at different distances, mainly mid-arm sections of the Perseus and Sagittarius spiral arms and the tangent of the Scutum-Centaurus arm, which is coincident with the end of the Galactic long bar. By utilizing the catalogued cloud distances plus new kinematic distance determinations, we are able to separate the dense BGPS clumps into these three main line-of-sight components to look for variations in star formation properties that might be related to the different Galactic environments. We find no evidence of any difference in either the clump mass function or the average clump formation efficiency (CFE) between these components that might be attributed to environmental effects on scales comparable to Galactic structure features.
- ID:
- ivo://CDS.VizieR/J/A+A/327/325
- Title:
- Distances of molecular cloud
- Short Name:
- J/A+A/327/325
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used a deep CO survey (at 115GHz) of the third galactic quadrant (May et al., 1993A&AS...99..105M) to derive the physical properties of molecular clouds in the outer Galaxy. Within the range of this survey, from 194{deg} to 270{deg} in galactic longitude, 177 molecular clouds have been identified beyond 2 kpc from the Sun. Distances have been determined kinematically using the rotation curve of Brand (1986, Ph.D. Thesis, University of Leiden) with R_{sun}_=8.5kpc and {Theta}_{sun}_=220km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A51
- Title:
- Distances to molecular clouds in SFR
- Short Name:
- J/A+A/633/A51
- Date:
- 14 Jan 2022 08:01:32
- Publisher:
- CDS
- Description:
- Accurate distances to local molecular clouds are critical for understanding the star and planet formation process, yet distance measurements are often obtained inhomogeneously on a cloud-by-cloud basis. We have recently developed a method which combines stellar photometric data with Gaia DR2 parallax measurements in a Bayesian framework to infer the distances of nearby dust clouds to a typical accuracy of ~5%. After refining the technique to target lower latitudes and incorporating deep optical data from DECam in the southern Galactic plane, we have derived a catalog of distances to molecular clouds in Reipurth (2008, Star Formation Handbook, vols I and II) which contains a large fraction of the molecular material in the solar neighborhood. Comparison with distances derived from maser parallax measurements towards the same clouds shows our method produces consistent distances with <10% scatter for clouds across our entire distance spectrum (150pc-2.5kpc). We hope this catalog of homogeneous distances will serve as a baseline for future work.
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/1822
- Title:
- Distances to nine dark globules
- Short Name:
- J/MNRAS/369/1822
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Distances to nine dark globules are determined by a method using optical (VRI) and near-infrared (near-IR) (JHK) photometry of stars projected towards the field containing the globules. In this method, we compute intrinsic colour indices of stars projected towards the direction of the globule by dereddening the observed colour indices using various trial values of extinction A_V_ and a standard extinction law.
- ID:
- ivo://CDS.VizieR/J/ApJ/672/930
- Title:
- Distant CO clouds in third galactic quadrant
- Short Name:
- J/ApJ/672/930
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine optical and radio observations to trace the spiral structure in the third quadrant of the Milky Way. The optical observations consist of a large sample of young open clusters and associations, whereas the radio observations consist of a survey of nearby and distant clouds observed in CO. Both the optical and radio samples are the largest ones thus far presented in the literature. We use this unique material to analyze the behavior of interstellar extinction and to trace the detailed structure of the third Galactic quadrant (TGQ).
- ID:
- ivo://CDS.VizieR/J/A+A/590/A93
- Title:
- Doubly ^13^C-substituted ethyl cyanide
- Short Name:
- J/A+A/590/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. Line intensities of the main isotopic species of ethyl cyanide and its singly ^13^C-substituted isotopomers observed toward the hot molecular core Sagittarius B2(N2) suggest that the doubly ^13^C-substituted isotopomers should also be detectable. We want to determine the spectroscopic parameters of all three doubly ^13^C-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. We investigated the laboratory rotational spectra of the three species between 150GHz and 990GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the ^12^C and singly ^13^C-substituted isotopologues assuming local thermodynamic equilibrium.
