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Start Over Subject milky way galaxy Subject radio astronomy
1. Accurate OH maser positions from SPLASH. III.
ID:
ivo://CDS.VizieR/J/ApJS/247/5
Title:
Accurate OH maser positions from SPLASH. III.
Short Name:
J/ApJS/247/5
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present high spatial resolution observations of ground-state OH masers achieved with the Australia Telescope Compact Array (ATCA). These observations targeted 253 pointing centers containing OH maser candidates at all four ground-state OH transitions identified in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) across 96deg^2^ of the southern Galactic plane (332{deg}<l<334{deg} and -2{deg}<b<+2{deg}, 344{deg}<l<355{deg} and -2{deg}<b<+2{deg}, 358{deg}<l<4{deg} and +2{deg}<b<+6{deg}, 5{deg}<l<10{deg} and -2{deg}<b<+2{deg}). We detect maser emission toward 236 fields and suggest that 7 out of 17 nondetections are due to the slightly lower sensitivity of the ATCA observations, combined with some temporal variability. The superior resolution provided by the ATCA data has allowed us to identify 362 OH maser sites in the 236 target fields. Almost half (160 of 362) of these masers have been detected for the first time. Comparison between these 362 maser sites and information presented in the literature allowed us to categorize 238 sites as evolved star sites (66%), 63 as star formation (17%), 8 as supernova remnants, and 53 as unknown maser sites (15%). We present an analysis of the OH masers across the full SPLASH survey range (176deg^2^) and find that the detection rate of 1.7GHz radio continuum sources (18%) is lower than that previously found at 8.2 and 9.2GHz (38%). We also find that the velocity separations of evolved star sites with symmetric 1612MHz maser profiles are generally smaller than those with asymmetric profiles.
2. A 4-6GHz RRL survey in the Milky Way
ID:
ivo://CDS.VizieR/J/ApJS/248/3
Title:
A 4-6GHz RRL survey in the Milky Way
Short Name:
J/ApJS/248/3
Date:
21 Oct 2021
Publisher:
CDS
Description:
We performed a radio recombination line (RRL) survey to construct a high-mass star-forming region (HMSFR) sample in the Milky Way based on the all-sky Wide-Field Infrared Survey Explorer point-source catalog. The survey was observed with the Shanghai 65m Tianma radio telescope covering 10 hydrogen RRL transitions ranging from H98{alpha} to H113{alpha} (corresponding to the rest frequencies of 4.5-6.9GHz) simultaneously. Out of 3348 selected targets, we identified an HMSFR sample consisting of 517 sources traced by RRLs; a large fraction of this sample (486) is located near the Galactic Plane (|b|<2{deg}). In addition to the hydrogen RRLs, we also detected helium and carbon RRLs toward 49 and 23 sources, respectively. We crossmatch the RRL detections with the 6.7 methanol maser sources built up in previous works for the same target sample. As a result, 103 HMSFR sources were found to harbor both emissions. In this paper, we present the HMSFR catalog accompanied by the measured RRL line properties and a correlation with our methanol maser sample, which is believed to trace massive stars at earlier stages. The construction of an HMSFR sample consisting of sources in various evolutionary stages indicated by different tracers is fundamental for future studies of high-mass star formation in such regions.
3. AMI Galactic Plane Survey at 16GHz. I.
ID:
ivo://CDS.VizieR/J/MNRAS/429/3330
Title:
AMI Galactic Plane Survey at 16GHz. I.
Short Name:
J/MNRAS/429/3330
Date:
21 Oct 2021
Publisher:
CDS
Description:
The AMI Galactic Plane survey is being made with the Arcminute Microkelvin Imager (AMI) Small Array at 15.7GHz and with resolution of approximately 3arcmin. This is the first data release, covering ~868deg^2^ of the Northern Galactic plane between |b|~+/-5{deg} and above {delta}=40{deg} with a noise level of ~3mJy/beam away from bright sources. The source catalogue contains a total of 3503 sources.
4. AMI Galactic Plane Survey at 16GHz. II.
ID:
ivo://CDS.VizieR/J/MNRAS/453/1396
Title:
AMI Galactic Plane Survey at 16GHz. II.
Short Name:
J/MNRAS/453/1396
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Arcminute Microkelvin Imager Galactic Plane Survey (AMIGPS) provides mJy-sensitivity, arcminute-resolution interferometric images of the northern Galactic plane at ~16GHz. The first data release covered 76{deg}<=l<=170{deg} between latitudes of |b|<=5{deg}; here we present a second data release, extending the coverage to 53{deg}<=l<=193{deg} and including high-latitude extensions to cover the Taurus and California giant molecular cloud regions, and the recently discovered large supernova remnant G159.6+7.3. The total coverage is now 1777{deg}^2^ and the catalogue contains 6509 sources. We also describe the improvements to the data processing pipeline which improves the positional and flux density accuracies of the survey.
5. 8.35 and 14.35GHz flux at Galactic plane
ID:
ivo://CDS.VizieR/J/AJ/119/2801
Title:
8.35 and 14.35GHz flux at Galactic plane
Short Name:
J/AJ/119/2801
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first images of the Galactic plane (GP; |b|<5{deg}, -15{deg}<l<255{deg}) at 8.35 and 14.35 GHz. These observations used the National Radio Astronomy Observatory-NASA Green Bank Earth Station to survey the sky simultaneously at these frequencies. These are the first results from the GP survey observations, a program to monitor the sky at 8.35 and 14.35 GHz. The GP survey series is intended to detect short-lived radio sources. We present four independent observations of the Galactic plane, combined to provide a set of reference images of the Galactic plane. The first survey, GPA, covers 0.82 sr (6.5%) of the sky. A source list is presented for all sources brighter than 0.9 Jy at 8.35 GHz and also for all sources brighter than 2.5 Jy at 14.35 GHz. The FITS format images, residual images, source lists, and archive data are available over the Internet. Later papers will present the results of the variable source search.
6. ATLASGAL: dust condensations in Galactic plane
ID:
ivo://CDS.VizieR/J/A+A/565/A75
Title:
ATLASGAL: dust condensations in Galactic plane
Short Name:
J/A+A/565/A75
Date:
21 Oct 2021
Publisher:
CDS
Description:
The formation processes and the evolutionary stages of high-mass stars are poorly understood compared to low-mass stars. Large-scale surveys are needed to provide an unbiased census of high column density sites which can potentially host precursors to high-mass stars. The ATLASGAL survey covers 420 sq. degree of the Galactic plane, between -80{deg}<l<+60{deg} at 870um. Here we identify the population of embedded sources throughout the inner Galaxy. With this catalog we first investigate the general statistical properties of dust condensations in terms of their observed parameters, such as flux density and angular size. Then using mid-IR surveys we aim to investigate their star-formation activity and the Galactic distribution of star-forming and quiescent clumps. Our ultimate goal is to determine the statistical properties of quiescent and star-forming clumps within the Galaxy and to constrain the star-formation processes. We optimized the source extraction method, referred to as MRE-GCL, for the ATLASGAL maps in order to generate a catalog of compact sources. This technique is based on a multi-scale filtering to remove extended emission from clouds to better determine the parameters corresponding to the embedded compact sources. In a second step we extract the sources by fitting 2D Gaussians with the Gaussclumps algorithm.
7. ATLASGAL 6.7GHz methanol masers
ID:
ivo://CDS.VizieR/J/MNRAS/431/1752
Title:
ATLASGAL 6.7GHz methanol masers
Short Name:
J/MNRAS/431/1752
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the 870um APEX Telescope large area survey of the Galaxy, we have identified 577 submillimetre continuum sources with masers from the methanol multibeam survey in the region 280{deg}<l<20{deg}; |b|<1.5{deg}. 94 per cent of methanol masers in the region are associated with submillimetre dust emission. We estimate masses for ~450 maser-associated sources and find that methanol masers are preferentially associated with massive clumps. These clumps are centrally condensed, with envelope structures that appear to be scale-free, the mean maser position being offset from the peak column density by 0+/-4 arcsec. Assuming a Kroupa initial mass function and a star formation efficiency of ~30 per cent, we find that over two-thirds of the clumps are likely to form clusters with masses >20M_{sun}_. Furthermore, almost all clumps satisfy the empirical mass-size criterion for massive star formation. Bolometric luminosities taken from the literature for ~100 clumps range between ~100 and 10^6^L_{sun}_. This confirms the link between methanol masers and massive young stars for 90 per cent of our sample. The Galactic distribution of sources suggests that the star formation efficiency is significantly reduced in the Galactic Centre region, compared to the rest of the survey area, where it is broadly constant, and shows a significant drop in the massive star formation rate density in the outer Galaxy.
8. BGPS. IX. Data release 2.
ID:
ivo://CDS.VizieR/J/ApJS/208/14
Title:
BGPS. IX. Data release 2.
Short Name:
J/ApJS/208/14
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a re-reduction and expansion of the Bolocam Galactic Plane Survey (BGPS), first presented by Aguirre+ (2011ApJS..192....4A) and Rosolowsky+ (2011, J/ApJS/188/123). The BGPS is a 1.1mm survey of dust emission in the Northern galactic plane, covering longitudes -10{deg}<{ell}<90{deg} and latitudes |b|<0.5{deg} with a typical 1{sigma} rms sensitivity of 30-100mJy in a ~33" beam. Version 2 of the survey includes an additional ~20deg^2^ of coverage in the third and fourth quadrants and ~2deg^2^ in the first quadrant. The new data release has improved angular recovery, with complete recovery out to ~80" and partial recovery to ~300", and reduced negative bowls around bright sources resulting from the atmospheric subtraction process. We resolve the factor of 1.5 flux calibration offset between the v1.0 data release and other data sets and determine that there is no offset between v2.0 and other data sets. The v2.0 pointing accuracy is tested against other surveys and is demonstrated to be accurate and an improvement over v1.0. We present simulations and tests of the pipeline and its properties, including measurements of the pipeline's angular transfer function. The Bolocat cataloging tool was used to extract a new catalog, which includes 8594 sources, with 591 in the expanded regions. We have demonstrated that the Bolocat 40" and 80" apertures are accurate even in the presence of strong extended background emission. The number of sources is lower than in v1.0, but the amount of flux and area included in identified sources is larger.
9. Catalog of 5 GHz Galactic Plane Sources
ID:
ivo://CDS.VizieR/VIII/20
Title:
Catalog of 5 GHz Galactic Plane Sources
Short Name:
VIII/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is a catalog of 915 sources in the galactic plane between l=190 - 360 - 40 for -2 < b < 2. The l, b pair of galactic coordinates is given in columns 1 and 2 and essentially constitutes the galactic source name. The 1950 equatorial coordinates for each source are given in columns 3 and 4, and values for the peak brightness temperature and flux density are given in columns 5 and 6. The reader should refer to Section 3 of the source reference for information relating to the determination of the flux densities. Column 7 gives an estimate of the source extension in minutes of arc. Extents are given for source in nonconfused regions only. Finally, in column 8 comments on each source are included where appropriate. Identifications with known supernova remnants are included from the compilation of Clark and Caswell (1976MNRAS.174..267C). Identifications with HII regions are based principally on H109alpha recombination-line emission data, which are mostly obtained from Wilson et al. (1970A&A.....6..364W) but with some unpublished Parkes observations included also.
10. CH_3_OH & OH line emission from Galactic center
ID:
ivo://CDS.VizieR/J/ApJS/227/10
Title:
CH_3_OH & OH line emission from Galactic center
Short Name:
J/ApJS/227/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
Class I methanol masers are collisionally pumped and are generally correlated with outflows in star-forming sites in the Galaxy. Using the Very Large Array in its A-array configuration, we present a spectral line survey to identify methanol J=4_-1_->3_0_E emission at 36.169GHz. Over 900 pointings were used to cover a region 66'x13' along the inner Galactic plane. A shallow survey of OH at 1612, 1665, 1667, and 1720MHz was also carried out over the area covered by our methanol survey. We provide a catalog of 2240 methanol masers with narrow line-widths of ~1km/s, spatial resolutions of ~0.14"x0.05", and rms noises ~20mJy/beam per channel. Lower limits on the brightness temperature range from 27000 to 10000000K, showing that the emission is of non-thermal origin. We also provide a list of 23 OH (1612), 14 OH (1665), 5 OH (1667), and 5 OH (1720MHz) masers. The origin of such a large number of methanol masers is not clear. Many methanol masers appear to be associated with infrared dark clouds, though it appears unlikely that the entire population of these masers traces the early phase of star formation in the Galactic center.