- ID:
- ivo://CDS.VizieR/J/MNRAS/376/371
- Title:
- Polarisation of flat-spectrum radio sources
- Short Name:
- J/MNRAS/376/371
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the very large JVAS/CLASS 8.4GHz surveys of flat-spectrum radio sources to obtain a large, uniformly observed and calibrated, sample of radio source polarizations. These are useful for many investigations of the properties of radio sources and the interstellar medium. We discuss comparisons with polarization measurements from this survey and from other large-scale surveys of polarization in flat-spectrum sources.
Number of results to display per page
Search Results
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/541/A52
- Title:
- Polarization efficiency and dust phase
- Short Name:
- J/A+A/541/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compiled the polarimetric data for a sample of lines of sight with known abundances of Mg, Si, and Fe. We correlated the degree of interstellar polarization P and polarization efficiency (the ratio of P to the colour excess E(B-V) or extinction AV) with dust phase abundances. We detect an anticorrelation between P and the dust phase abundance of iron in non silicate-containing grains [Fe(rest)/H]_d_, a correlation between P and the abundance of Si, and no correlation between P/E(B-V) or P/AV and dust phase abundances. These findings can be explained if mainly the silicate grains aligned by the radiative mechanism are responsible for the observed interstellar linear polarization.
- ID:
- ivo://CDS.VizieR/J/ApJ/775/84
- Title:
- Polarization from stars behind IC63 nebula
- Short Name:
- J/ApJ/775/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the interstellar medium (ISM), molecular hydrogen is expected to form almost exclusively on the surfaces of dust grains. Due to that molecule's large formation energy (-4.5eV), several dynamical effects are likely associated with the process, including the alignment of asymmetric dust grains with the ambient magnetic field. Such aligned dust grains are, in turn, believed to cause the broadband optical/infrared polarization observed in the ISM. Here, we present the first observational evidence for grain alignment driven by H_2_ formation, by showing that the polarization of the light from stars behind the reflection nebula IC 63 appears to correlate with the intensity of H_2_ fluorescence. While our results strongly suggest a role for "Purcell rockets" in grain alignment, additional observations are needed to conclusively confirm their role. By showing a direct connection between H_2_ formation and a probe of the dust characteristics, these results also provide one of the first direct confirmations of the grain-surface formation of H_2_. We compare our observations to ab initio modeling based on Radiative Torque Alignment (RAT) theory.
