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51. Galactic MCs associated with HII regions
ID:
ivo://CDS.VizieR/J/ApJ/831/73
Title:
Galactic MCs associated with HII regions
Short Name:
J/ApJ/831/73
Date:
21 Oct 2021
Publisher:
CDS
Description:
The relations between star formation and properties of molecular clouds (MCs) are studied based on a sample of star-forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of associated MCs and dense clumps. Radio continuum emission and mid-infrared emission were used to determine star formation rates (SFRs), while ^13^CO and submillimeter dust continuum emission were used to obtain the masses of molecular and dense gas, respectively. We test whether total molecular gas or dense gas provides the best predictor of SFR. We also test two specific theoretical models, one relying on the molecular mass divided by the free-fall time, the other using the free-fall time divided by the crossing time. Neither is supported by the data. The data are also compared to those from nearby star-forming regions and extragalactic data. The star formation "efficiency," defined as SFR divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all of the molecular gas.
52. Galactic midplane Spitzer red sources
ID:
ivo://CDS.VizieR/J/AJ/136/2413
Title:
Galactic midplane Spitzer red sources
Short Name:
J/AJ/136/2413
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a highly reliable flux-limited census of 18949 point sources in the Galactic midplane that have intrinsically red mid-infrared colors. These sources were selected from the Spitzer Space Telescope Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE) I and II surveys of 274{deg}^2^ of the Galactic midplane, and consist mostly of high- and intermediate-mass young stellar objects (YSOs) and asymptotic giant branch (AGB) stars. The selection criteria were carefully chosen to minimize the effects of position-dependent sensitivity, saturation, and confusion. The distribution of sources on the sky and their location in the Infrared Array Camera and the Multiband Image Photometer for Spitzer 24um color-magnitude and color-color space are presented. Using this large sample, we find that YSOs and AGB stars can be mostly separated by simple color-magnitude selection criteria into approximately 50%-70% of YSOs and 30%-50% of AGB stars. Planetary nebulae and background galaxies together represent at most 2%-3% of all the red sources. 1004 red sources in the GLIMPSE II region, mostly AGB stars with high mass-loss rates, show significant (>=0.3mag) variability at 4.5 and/or 8.0um. With over 11,000 likely YSOs and over 7000 likely AGB stars, this is to date the largest uniform census of AGB stars and high- and intermediate-mass YSOs in the Milky Way Galaxy.
53. Galactic plane dust temperature maps with Herschel
ID:
ivo://CDS.VizieR/J/A+A/564/A111
Title:
Galactic plane dust temperature maps with Herschel
Short Name:
J/A+A/564/A111
Date:
21 Oct 2021
Publisher:
CDS
Description:
Dust grains absorb the interstellar far ultra-violet and visible photons and re-emit them in far-infrared (FIR) wavebands. The dust FIR continuum can be predicted by a grid of models using various values of the interstellar radiation field. We analyze the dust continuum emission in two Hi-GAL science-demonstration phase (SDP) fields using both the radiative transfer code, Cloudy, and the DustEM dust model, to explore the effect of radiative transfer on dust temperature. The 500um sub-millimeter excess emission and the very small grain (VSG) contribution to the 70um intensity are investigated by spectral energy distribution (SED) fitting using the Cloudy model.
54. Galactic plane VERA survey
ID:
ivo://CDS.VizieR/J/PASJ/52/631
Title:
Galactic plane VERA survey
Short Name:
J/PASJ/52/631
Date:
21 Oct 2021
Publisher:
CDS
Description:
In order to search for new VLBI sources in the galactic plane that can be used as phase reference sources in differential VLBI, we conducted 22GHz observations of radio sources in the galactic plane using the Japanese VLBI Network (J-Net). We have observed 267 VLBI source candidates selected from existing radio surveys and have detected 93 sources at a signal-to-noise ratio larger than 5. While 42 of the 93 detected sources had already been detected with VLBI at relatively lower frequency (typically 2 to 8GHz), the remaining 51 are found to be new VLBI sources detected for the first time. These are located within |b|<=5{deg}, and have a large number of galactic maser sources around them. Thus, they are potential candidates for phase reference sources for VLBI Exploration of Radio Astrometry (VERA), which is the first VLBI array dedicated to phase-referencing VLBI astrometry aimed at measuring the parallax and proper motion of maser sources in the whole Galaxy.
55. Galactic plane VLA survey
ID:
ivo://CDS.VizieR/J/AJ/96/1655
Title:
Galactic plane VLA survey
Short Name:
J/AJ/96/1655
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a continuum VLA snapshot survey of the galactic plane in the longitude range 0{deg}<=l<=90{deg} at 1.5GHz. Observations were taken every 0.5{deg} in longitude at b=0{deg}. Most fields are complete to about 30mJy peak flux density. The positions, peak, and total flux density of 471 compact sources (<30") have been measured. A complete sample of 329 sources is defined. An excess of sources above that expected from extragalactic source counts is seen for l<40{deg} at all flux-density intervals. We find 86 compact sources that are within 2.4arcmin of a source in the recent radio recombination-line survey of Lockman (1989ApJS...71..469L) Source counts excluding these 86 sources agree with extragalactic source counts for all flux-density and longitude intervals. there may only be a small number of galactic objects present in this survey that remain unidentified as such.
56. Galactic Worms
ID:
ivo://CDS.VizieR/J/ApJ/390/108
Title:
Galactic Worms
Short Name:
J/ApJ/390/108
Date:
21 Oct 2021
Publisher:
CDS
Description:
A catalog of candidates for the Galactic Worms that are possibly the walls surrounding the superbubbles is compiled; 118 isolated structures that appear both in HI and in IR (60 and 100{mu}m). 52 are possibly associated with HII regions. It is found that the 100-{mu}m emissivity increases systematically toward the Galactic interior, which is consistent with the increase of the general interstellar radiation field. The 100-{mu}m emissivity of the structures associated with the HII regions is larger than that of the structures without associated HII regions. The 60-100{mu}m ratio is large, 0.28+/-0.03, which may indicate that the grains associated with the atomic gas have a relatively large population of small grains. 35 structures appear in the 408MHz continuum. The IR and the radio continuum properties suggest that the 408MHz continuum emission in those structures is very likely thermal. The implications of these results on the ionization of gas far from the Galactic plane are discussed.
57. Gal. midplane Spitzer/IRAC candidate YSOs (SPICY)
ID:
ivo://CDS.VizieR/J/ApJS/254/33
Title:
Gal. midplane Spitzer/IRAC candidate YSOs (SPICY)
Short Name:
J/ApJS/254/33
Date:
19 Jan 2022 09:09:49
Publisher:
CDS
Description:
We present ~120000 Spitzer/IRAC candidate young stellar objects (YSOs) based on surveys of the Galactic midplane between l~255{deg} and 110{deg}, including the GLIMPSE I, II, and 3D, Vela-Carina, Cygnus X, and SMOG surveys (613 square degrees), augmented by near-infrared catalogs. We employed a classification scheme that uses the flexibility of a tailored statistical learning method and curated YSO data sets to take full advantage of Spitzer's spatial resolution and sensitivity in the mid-infrared ~3-9{mu}m range. Multiwavelength color/magnitude distributions provide intuition about how the classifier separates YSOs from other red IRAC sources and validate that the sample is consistent with expectations for disk/envelope-bearing pre-main-sequence stars. We also identify areas of IRAC color space associated with objects with strong silicate absorption or polycyclic aromatic hydrocarbon emission. Spatial distributions and variability properties help corroborate the youthful nature of our sample. Most of the candidates are in regions with mid-IR nebulosity, associated with star-forming clouds, but others appear distributed in the field. Using Gaia DR2 distance estimates, we find groups of YSO candidates associated with the Local Arm, the Sagittarius-Carina Arm, and the Scutum-Centaurus Arm. Candidate YSOs visible to the Zwicky Transient Facility tend to exhibit higher variability amplitudes than randomly selected field stars of the same magnitude, with many high-amplitude variables having light-curve morphologies characteristic of YSOs. Given that no current or planned instruments will significantly exceed IRAC's spatial resolution while possessing its wide-area mapping capabilities, Spitzer-based catalogs such as ours will remain the main resources for mid-infrared YSOs in the Galactic midplane for the near future.
58. GaussPy+ decomposition of Galactic Ring Survey
ID:
ivo://CDS.VizieR/J/A+A/633/A14
Title:
GaussPy+ decomposition of Galactic Ring Survey
Short Name:
J/A+A/633/A14
Date:
21 Oct 2021
Publisher:
CDS
Description:
The analysis of large molecular line surveys of the Galactic plane is essential for our understanding of the gas kinematics on Galactic scales and, in particular, its link with the formation and evolution of dense structures in the interstellar medium. An approximation of the emission peaks with Gaussian functions allows for an efficient and straightforward extraction of useful physical information contained in the shape and Doppler-shifted frequency of the emission lines contained in these enormous data sets. In this work, we present an overview and the first results of a Gaussian decomposition of the entire Galactic Ring Survey (GRS) ^13^CO (1-0) data that consists of about 2.3 million spectra. We performed the decomposition with the fully automated GaussPy+ algorithm and fitted about 4.6 million Gaussian components to the GRS spectra. These decomposition results enable novel and unexplored ways to interpret and study the gas velocity structure. We discuss the statistics of the fit components and relations between the fitted intensities, velocity centroids, and velocity dispersions. We find that the magnitude of the velocity dispersion values increase towards the inner Galaxy and around the Galactic midplane, which we speculate is partly due to the influence of the Galactic bar and regions with higher non-thermal motions located in the midplane, respectively. We also used our decomposition results to infer global properties of the gas emission and find that the number of fit components used per spectrum is indicative of the amount of structure along the line of sight. We find that the emission lines from regions located on the far side of the Galaxy show increased velocity dispersion values, which are likely due to beam averaging effects. We demonstrate how this trend has the potential to aid in characterising Galactic structure by disentangling emission that belongs to the nearby Aquila Rift molecular cloud from emission that is more likely associated with the Perseus and Outer spiral arms. With this work, we also make our entire decomposition results available.
59. 90GHz obs. of high-mass star-forming regions
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.
60. 86GHz SiO maser survey in the Inner Galaxy
ID:
ivo://CDS.VizieR/J/A+A/418/103
Title:
86GHz SiO maser survey in the Inner Galaxy
Short Name:
J/A+A/418/103
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a compilation and study of DENIS, 2MASS, ISOGAL, MSX and IRAS 1-25 microns photometry for a sample of 441 late-type stars in the inner Galaxy, which we previously searched for 86GHz SiO maser emission (Messineo et al., 2002, Cat. <J/A+A/393/115>). The comparison of the DENIS and 2MASS J and Ks magnitudes shows that most of the SiO targets are indeed variable stars. The MSX colours and the IRAS [12]-[25] colour of our SiO targets are consistent with those of Mira type stars with dust silicate feature at 9.7 microns feature in emission, indicating only a moderate mass-loss rate.

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