- 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.
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- ID:
- ivo://CDS.VizieR/J/A+A/524/A99
- Title:
- Polarisation of S Per and VX Sgr in OH
- Short Name:
- J/A+A/524/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two red supergiant star S Per and VX Sgr were observed in the OH 1612 and 1667MHz maser lines with the Nancay radio telescope at several runs in 2002-2005 and 2002-2008, respectively. Both targets were sampled at irregular intervals of 2-3 days up to 4 months. Time series of OH spectra in the Stokes parameters I, Q, U and V are presented. The spectra of the linearly polarized flux density, p=sqrt{Q^2^+U^2^}, the degrees of circular polarization, m_C_=V/I linear polarization, m_L_=p/I, and position angle, {chi}=0.5xtan^-1^(U/Q), drived from the Stokes parameters are also given. The degrees of polarization at 1667MHz show diverse behaviours usually uncorrelated with the total flux, whereas those at 1612MHz are commonly stable on time scales of 4-6yr. Several outbursts of the 1667MHz emission on time scales of 0.5-2yr were found in both targets. The bursting features are highly polarized and show drifts in velocity. Small changes of the degrees of polarization and smooth variations of position angle of linear polarization during the bursts were observed in S Per but they are more dramatic in VX Sgr.
- ID:
- ivo://CDS.VizieR/J/A+A/636/A24
- Title:
- Polarised radiative transfer angular quadratures
- Short Name:
- J/A+A/636/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In three-dimensional (3D) radiative transfer (RT) problems, the tensor product quadratures are generally not optimal in terms of the number of discrete ray directions needed for a given accuracy of the angular integration of the radiation field. In this paper, we derive a new set of angular quadrature rules that are more suitable for solving 3D RT problems with the short- and long-characteristics formal solvers. These quadratures are more suitable than the currently used ones for the numerical calculation of the radiation field tensors that are relevant in the problem of the generation and transfer of polarised radiation without assuming local thermodynamical equilibrium (non-LTE). We show that our new quadratures can save up to about 30% of computing time with respect to the Gaussian-trapezoidal product
- ID:
- ivo://CDS.VizieR/J/ApJ/794/54
- Title:
- Polarization and photometry for blazar W Comae
- Short Name:
- J/ApJ/794/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An R-band photopolarimetric variability analysis of the TeV bright blazar W Comae between 2008 February 28 and 2013 May 17 is presented. The source showed a gradual tendency to decrease its mean flux level with a total change of 3 mJy. A maximum and minimum brightness states in the R band of 14.25+/-0.04 and 16.52+/-0.1 mag, respectively, were observed, corresponding to a maximum variation of {Delta}F=5.40 mJy. We estimated a minimum variability timescale of {Delta}t=3.3 days. A maximum polarization degree P=33.8%+/-1.6%, with a maximum variation of {Delta}P=33.2%, was found. One of our main results is the detection of a large rotation of the polarization angle from 78{deg} to 315{deg} ({Delta}{theta}~237{deg}) that coincides in time with the {gamma}-ray flare observed in 2008 June. This result indicates that both optical and {gamma}-ray emission regions could be co-spatial. During this flare, a correlation between the R-band flux and polarization degree was found with a correlation coefficient of r_F-p _=0.93+/-0.11. From the Stokes parameters, we infer the existence of two optically thin synchrotron components that contribute to the polarized flux. One of them is stable with a constant polarization degree of 11%. Assuming a shock-in jet model during the 2008 flare, we estimated a maximum Doppler factor {delta}_D_~27 and a minimum of {delta}_D_~16; a minimum viewing angle of the jet ~2.0{deg}; and a magnetic field B~0.12 G.
- ID:
- ivo://CDS.VizieR/J/A+A/368/912
- Title:
- Polarization and rotational velocities of Be stars
- Short Name:
- J/A+A/368/912
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of statistical analyses of a sample of 628 Be stars. The parameters of intrinsic polarization p_*_, projected rotational velocity (vsini), and near IR excesses have been investigated. The values of p_*_ have been estimated for a much larger and more representative sample of Be stars (~490 objects) than previously.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/54
- Title:
- Polarization around star-forming regions
- Short Name:
- J/ApJ/743/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper combines new CCD polarimetric data with previous information about protostellar objects in a search for correlations involving the interstellar magnetic field (ISMF). Specifically, we carried out an optical polarimetric study of a sample of 28 fields of 10'x10' located in the neighborhood of protostellar jets and randomly spread over the Galaxy. The polarimetry of a large number of field stars is used to estimate both the average and dispersion of the ISMF direction in each region. The results of the applied statistical tests are as follows. Concerning the alignment between the jet direction and the ISMF, the whole sample does not show alignment. There is, however, a statistically significant alignment for objects of Classes 0 and I. Regarding the ISMF dispersion, our sample presents values slightly larger for regions containing T Tauri objects than for those harboring younger protostars. Moreover, the ISMF dispersion in regions containing high-mass objects tends to be larger than in those including only low-mass protostars. In our sample, the mean interstellar polarization as a function of the average interstellar extinction in a region reaches a maximum value around 3% for A(V)=5, after which it decreases. Our data also show a clear correlation of the mean value of the interstellar polarization with the dispersion of the ISMF: the larger the dispersion, the smaller the polarization. Based on a comparison of our and previous results, we suggest that the dispersion in regions forming stars is larger than in quiescent regions.
- ID:
- ivo://CDS.VizieR/J/A+A/561/A24
- Title:
- Polarization at high galactic latitude
- Short Name:
- J/A+A/561/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured the interstellar polarization for 2400 stars at the distances of up to 600pc and within 60 degrees and 30 degrees from the north and south Galactic poles. These data were used to make interstellar polarization maps of the regions around the north (b>30) and south (b<-60) poles. The new maps give wider and higher resolution views of interstellar polarization at high galactic latitudes and show significant asymmetries in the polarization, one in the northern sky directly across the local spiral and the second between the northern and southern Galactic hemispheres.
- ID:
- ivo://CDS.VizieR/II/34A
- Title:
- Polarization Catalogue
- Short Name:
- II/34A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue is an extension of the catalogue compiled by Mathewson and Ford (1970MmRAS..74..139M) and the list by Klare and Neckel (1977A&AS...27..215K).
- ID:
- ivo://CDS.VizieR/J/A+A/372/276
- Title:
- Polarization catalogue for NGP area
- Short Name:
- J/A+A/372/276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of interstellar polarization measurements for the North Galactic Pole area (b>70{deg}). Our list contains 336 stars of spectral classes from A to K for which the linear polarization has been measured by us and other researchers. The data are useful for investigation of the distribution of dust, to estimate the amount of interstellar extinction and to map Galactic magnetic field at high galactic latitudes. We discuss also the data selection, sampling and completeness of the catalog.
- ID:
- ivo://CDS.VizieR/J/ApJ/847/92
- Title:
- Polarization data toward the protostar Serpens SMM1
- Short Name:
- J/ApJ/847/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high angular resolution dust polarization and molecular line observations carried out with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the Class 0 protostar Serpens SMM1. By complementing these observations with new polarization observations from the Submillimeter Array (SMA) and archival data from the Combined Array for Research in Millimeter- wave Astronomy (CARMA) and the James Clerk Maxwell Telescopes (JCMT), we can compare the magnetic field orientations at different spatial scales. We find major changes in the magnetic field orientation between large (~0.1pc) scales-where the magnetic field is oriented E-W, perpendicular to the major axis of the dusty filament where SMM1 is embedded-and the intermediate and small scales probed by CARMA (~1000au resolution), the SMA (~350au resolution), and ALMA (~140au resolution). The ALMA maps reveal that the redshifted lobe of the bipolar outflow is shaping the magnetic field in SMM1 on the southeast side of the source; however, on the northwestern side and elsewhere in the source, low-velocity shocks may be causing the observed chaotic magnetic field pattern. High-spatial-resolution continuum and spectral-line observations also reveal a tight (~130au) protobinary system in SMM1-b, the eastern component of which is launching an extremely high-velocity, one-sided jet visible in both CO(J=2->1) and SiO(J=5->4); however, that jet does not appear to be shaping the magnetic field. These observations show that with the sensitivity and resolution of ALMA, we can now begin to understand the role that feedback (e.g., from protostellar outflows) plays in shaping the magnetic field in very young, star-forming sources like SMM1.
