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1261. Polarisation of 404 radio sources at 6 and 20cm
ID:
ivo://CDS.VizieR/J/AJ/87/859
Title:
Polarisation of 404 radio sources at 6 and 20cm
Short Name:
J/AJ/87/859
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurate positions of 404 compact radio sources used as calibrators by the VLA are presented. In addition, the structure and polarization of each source at both 4885 and 1465MHz are given. Eighty-five percent of the sources have spectral indices flatter than 0.5; all of these are dominated by an unresolved core. Half of these flat-spectrum sources contain nearby, associated diffuse structure at a level exceeding approximately 0.4% of the core brightness at 20cm.
1262. Polarization in OMC 1/4
ID:
ivo://CDS.VizieR/J/ApJ/604/717
Title:
Polarization in OMC 1/4
Short Name:
J/ApJ/604/717
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use extensive 350{mu}m polarimetry and continuum maps obtained with the Hertz polarimeter and SHARC II (Submillimeter High Angular Resolution Camera II) along with HCN and HCO+ spectroscopic data to trace the orientation of the magnetic field in the Orion A star-forming region. Using the polarimetry data, we find that the direction of the projection of the magnetic field in the plane of the sky relative to the orientation of the integral-shaped filament varies considerably as one moves from north to south. By combining the polarimetry and spectroscopic data, we were able to measure a set of average values for the inclination angle of the magnetic field relative to the line of sight. We also present polarimetry data for the OMC-4 region located some 13' south of OMC-1.
1263. Polarization of extragalactic sources
ID:
ivo://CDS.VizieR/J/MNRAS/360/1305
Title:
Polarization of extragalactic sources
Short Name:
J/MNRAS/360/1305
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have observed a sample of 64 small-diameter sources towards the central -6<l<6, -2<b<2 of the Galaxy with the aim of studying the Faraday rotation measure near the Galactic Centre region. All the sources were observed at 6- and 3.6-cm wavelengths using the ATCA and the VLA. 59 of these sources are inferred to be extragalactic. The observations presented here constitute the first systematic study of the radio polarization properties of the background sources towards this direction and increase the number of known extragalactic radio sources in this part of the sky by almost an order of magnitude. Based on the morphology, spectral indices and lack of polarized emission, we identify four Galactic HII regions in the sample.
1264. Polarized DRAO sources
ID:
ivo://CDS.VizieR/J/ApJ/733/69
Title:
Polarized DRAO sources
Short Name:
J/ApJ/733/69
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Dominion Radio Astrophysical Observatory Deep Field polarization study has been matched with the Spitzer Wide-Area Infrared Extragalactic Survey of the European Large Area Infrared Space Observatory Survey North 1 field. We have used Very Large Array observations with a total intensity rms of 87uJy/beam to match SWIRE counterparts to the radio sources. Infrared color analysis of our radio sample shows that the majority of polarized sources are elliptical galaxies with an embedded active galactic nucleus. Using available redshift catalogs, we found 429 radio sources of which 69 are polarized with redshifts in the range of 0.04<z<3.2. We find no correlation between redshift and percentage polarization for our sample. However, for polarized radio sources, we find a weak correlation between increasing percentage polarization and decreasing luminosity.
1265. Polarized NVSS sources SEDs
ID:
ivo://CDS.VizieR/J/ApJS/212/15
Title:
Polarized NVSS sources SEDs
Short Name:
J/ApJS/212/15
Date:
21 Oct 2021
Publisher:
CDS
Description:
An understanding of cosmic magnetism requires converting the polarization properties of extragalactic radio sources into the rest-frame in which the corresponding polarized emission or Faraday rotation is produced. Motivated by this requirement, we present a catalog of multiwavelength linear polarization and total intensity radio data for polarized sources from the NRAO VLA Sky Survey. We cross-match these sources with a number of complementary measurements --combining data from major radio polarization and total intensity surveys such as AT20G, B3-VLA, GB6, NORTH6CM, Texas, and WENSS, together with other polarization data published over the last 50 years. For 951 sources, we present spectral energy distributions (SEDs) in both fractional polarization and total intensity, each containing between 3 and 56 independent measurements from 400MHz to 100GHz. We physically model these SEDs, and where available provide the redshift of the optical counterpart. For a superset of 25649 sources we provide the total intensity spectral index, {alpha}. Objects with steep versus flat {alpha} generally have different polarization SEDs: steep-spectrum sources exhibit depolarization, while flat-spectrum sources maintain constant polarized fractions over large ranges in wavelength. This suggests the run of polarized fraction with wavelength is predominantly affected by the local source environment, rather than by unrelated foreground magnetoionic material. In addition, a significant fraction (21%) of sources exhibit "repolarization," which further suggests that polarized SEDs are affected by different emitting regions within the source, rather than by a particular depolarization law. This has implications for the physical interpretation of future broadband polarimetric surveys.
1266. Polarized point sources in LOTSS-HETDEX
ID:
ivo://CDS.VizieR/J/A+A/613/A58
Title:
Polarized point sources in LOTSS-HETDEX
Short Name:
J/A+A/613/A58
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have produced a catalog of 92 polarized radio sources at 150MHz at 4.3-arcmin resolution and 1mJy rms sensitivity, which is the largest catalog of polarized sources at such low frequencies. The data used was from the LOFAR Two-Meter Sky Survey (LOTSS) initial release (Shimwell et al., 2017, Cat. J/A+A/598/A104), (10h45m-15h30m right ascension, 45-57{deg} declination, 570 square degrees).
1267. Polarized SiO masers of VX Sgr
ID:
ivo://CDS.VizieR/J/ApJ/728/149
Title:
Polarized SiO masers of VX Sgr
Short Name:
J/ApJ/728/149
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Submillimeter Array observations of high-frequency SiO masers around the supergiant VX Sgr and the semi-regular variable star W Hya. The J=5-4, v=1^28^SiO and v=0^29^SiO masers of VX Sgr are shown to be highly linearly polarized with a polarization from ~5% to 60%. Assuming the continuum emission peaks at the stellar position, the masers are found within ~60mas of the star, corresponding to ~100AU at a distance of 1.57kpc. The linear polarization vectors are consistent with a large-scale magnetic field, with position and inclination angles similar to that of the dipole magnetic field inferred in the H_2_O and OH maser regions at much larger distances from the star. We thus show for the first time that the magnetic field structure in a circumstellar envelope can remain stable from a few stellar radii out to ~1400AU. This provides further evidence supporting the existence of large-scale and dynamically important magnetic fields around evolved stars. Due to a lack of parallactic angle coverage, the linear polarization of masers around W Hya could not be determined. For both stars, we observed the ^28^SiO and ^29^SiO isotopologues and find that they have a markedly different distributions and that they appear to avoid each other. Additionally, emission from the SO 5_5_-4_4_ line was imaged for both sources. Around W Hya, we find a clear offset between the red- and blueshifted SO emission. This indicates that W Hya is likely host to a slow bipolar outflow or a rotating disk-like structure.
1268. 4 post-AGB stars datacubes
ID:
ivo://CDS.VizieR/J/A+A/648/A93
Title:
4 post-AGB stars datacubes
Short Name:
J/A+A/648/A93
Date:
22 Feb 2022
Publisher:
CDS
Description:
There is a class of binary post-AGB stars with a remarkable near-infrared excess that are surrounded by Keplerian or quasi-Keplerian disks and extended outflows composed of gas escaping from the disk. The Keplerian dynamics had been well identified in four cases, namely the Red Rectangle, AC Her, IW Car, and IRAS 08544-4431. In these objects, the mass of the outflow represents ~10% of the nebular mass, the disk being the dominant component of the nebula. We aim to study the presence of rotating disks in sources of the same class in which the outflow seems to be the dominant component. We present interferometric NOEMA maps of ^12^CO and ^13^CO J=2-1 in 89 Her and ^12^CO J=2-1 in AC Her, IRAS 19125+0343, and R Sct. Several properties of the nebula are obtained from the data and model fitting, including the structure, density, and temperature distributions, as well as the dynamics. We also discuss the uncertainties on the derived values. The presence of an expanding component in AC Her is doubtful, but thanks to new maps and models, we estimate an upper limit to the mass of this outflow of <=3x10^-5^M^{sun}_, that is, the mass of the outflow is <=5% of the total nebular mass. For 89 Her, we find a total nebular mass of 1.4x10^-2^M_{sun}_, of which ~50% comes from an hourglass-shaped extended outflow. In the case of IRAS 19125+0343, the nebular mass is 1.1x10^-2^M_{sun}_, where the outflow contributes ~70% of the total mass. The nebular mass of R Sct is 3.2x10^-2^M_{sun}_, of which ~75% corresponds to a very extended outflow that surrounds the disk. Our results for IRAS 19125+0343 and R Sct lead us to introduce a new subclass of binary post-AGB stars, for which the outflow is the dominant component of the nebula. Moreover, the outflow mass fraction found in AC Her is smaller than those found in other disk-dominated binary post-AGB stars. 89 Her would represent an intermediate case between both subclasses.
1269. Precise astrometry with VLBA (VIPS)
ID:
ivo://CDS.VizieR/J/AJ/142/89
Title:
Precise astrometry with VLBA (VIPS)
Short Name:
J/AJ/142/89
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present accurate positions for 857 sources derived from the astrometric analysis of 16 eleven-hour experiments from the Very Long Baseline Array imaging and polarimetry survey at 5GHz (VIPS). Among the observed sources, positions of 430 objects were not previously determined at milliarcsecond-level accuracy. For 95% of the sources the uncertainty of their positions ranges from 0.3 to 0.9mas, with a median value of 0.5mas. This estimate of accuracy is substantiated by the comparison of positions of 386 sources that were previously observed in astrometric programs simultaneously at 2.3/8.6GHz. Surprisingly, the ionosphere contribution to group delay was adequately modeled with the use of the total electron content maps derived from GPS observations and only marginally affected estimates of source coordinates.
1270. Precise positions of methanol masers
ID:
ivo://CDS.VizieR/J/other/PASA/26.454
Title:
Precise positions of methanol masers
Short Name:
J/other/PASA/26.
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Australia Telescope Compact Array (ATCA) has been used to determine positions for many southern methanol maser sites, with accuracy better than 1 arcsec. The results are presented here as a catalogue of more than 350 distinct sites, some of them new discoveries, and many others with positional precision 10-times better than existing published values. Clusters of 2 or 3 sites are occasionally found to account for single previously listed sources. This in turn reveals that the velocity range for each individual site is sometimes smaller than that of the originally tabulated (blended) source. Only a handful of examples then remain with a velocity range of more than 16km/s at a single compact (less than 2 arcsec) site. The precise methanol positions now allow apparent coincidences with OH masers to be confidently accepted or rejected; this has led to the important conclusion that, where a 1665-MHz OH maser lies in a massive star formation region, at more than 80 percent of the OH sites there is a precisely coincident methanol maser. The methanol precision achieved here will also allow clear comparisons with likely associated IR sources when the next generation of far-IR surveys produce precise positions.