- ID:
- ivo://CDS.VizieR/J/MNRAS/403/1577
- Title:
- Polarization towards open cluster NGC 6823
- Short Name:
- J/MNRAS/403/1577
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiwavelength linear polarimetric observations of 104 stars towards the region of young open cluster NGC 6823. The polarization towards NGC 6823 is dominated by foreground dust grains and we found evidence for the presence of several layers of dust towards the line of sight. The first layer of dust is approximately located within 200pc towards the cluster, which is much closer to the Sun than the cluster itself (~2.1kpc). The radial distribution of the position angles for the member stars is found to show a systematic change, while the polarization is found to reduce towards the outer parts of the cluster and the average position angle of the coronal region of the cluster is very close to the inclination of the Galactic parallel (~32{deg}). The size distribution of the grains within NGC 6823 is similar to those in the general interstellar medium. The patchy distribution of foreground dust grains is suggested to be mainly responsible for both differential reddening and polarization towards NGC 6823. The majority of the observed stars do not show evidence of intrinsic polarization in their light.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/111/399
- Title:
- Polarization variability in Herbig Ae/Be stars
- Short Name:
- J/A+AS/111/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report our measurements of linear polarization of a number of Herbig Ae/Be stars made at several epochs during the period 1989-1993. These results together with the observations compiled from the published sources have been analysed to study the variability of polarization in Herbig Ae/Be stars. It is found that polarimetric variability is a common feature of this class of objects. Most of the objects are variable on time scales >=1yr. Some objects have shown large variations on time scales as short as ~1 month indicating structural changes in the distribution of circumstellar matter close to the star within a few tens of stellar radii. Variations in the polarization position angle are not always correlated with variations in the degree of polarization.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/578/L6
- Title:
- Polarized images of MWC758
- Short Name:
- J/A+A/578/L6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of dynamical processes in protoplanetary disks is essential to understand planet formation. In this context, transition disks are prime targets because they are at an advanced stage of disk clearing and may harbor direct signatures of disk evolution. We aim to derive new constraints on the structure of the transition disk MWC758, to detect non-axisymmetric features and understand their origin. We obtained infrared polarized intensity observations of the protoplanetary disk MWC758 with SPHERE/VLT at 1.04 microns to resolve scattered light at a smaller inner working angle (0.093") and a higher angular resolution (0.027") than previously achieved. We observe polarized scattered light within 0.53" (148AU) down to the inner working angle (26AU) and detect distinct non-axisymmetric features but no fully depleted cavity. The two small-scale spiral features that were previously detected with HiCIAO are resolved more clearly, and new features are identified, including two that are located at previously inaccessible radii close to the star. We present a model based on the spiral density wave theory with two planetary companions in circular orbits. The best model requires a high disk aspect ratio (H/r~0.20 at the planet locations) to account for the large pitch angles which implies a very warm disk. Our observations reveal the complex morphology of the disk MWC758. To understand the origin of the detected features, the combination of high-resolution observations in the submillimeter with ALMA and detailed modeling is needed.
- 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.
- 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).
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A25
- Title:
- (Possible spiral in the disk around HD34282
- Short Name:
- J/A+A/649/A25
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- During the evolution of protoplanetary disks into planetary systems we expect to detect signatures that trace mechanisms such as planet-disk interaction. Protoplanetary disks display a large variety of structures in recently published high-spatial resolution images. However, the three-dimensional morphology of these disks is often difficult to infer from the two-dimensional projected images we observe. We aim to detect signatures of planet-disk interaction by studying the scattering surface of the protoplanetary disk around HD34282 We spatially resolved the disk using the high-contrast imager VLT/SPHERE in polarimetric imaging mode. We retrieved a profile for the height of the scattering surface to create a height-corrected deprojection, which simulates a face-on orientation. The detected disk displays a complex scattering surface. An inner clearing or cavity extending up to r<0.28" (88au) is surrounded by a bright inclined (i=56{deg}) ring with a position angle of 119{deg}. The center of this ring is offset from the star along the minor axis with 0.07", which can be explained with a disk height of 26au above the midplane. Outside this ring, beyond its southeastern ansa we detect an azimuthal asymmetry or blob at r~0.4". At larger separation, we detect an outer disk structure that can be fitted with an ellipse, which is compatible with a circular ring seen at r=0.62" (=190au) and a height of 77au. After applying a height-corrected deprojection we see a circular ring centered on the star at 88 au; what had seemed to be a separate blob and outer ring could now both be part of a single-armed spiral. We present the first scattered-light image of the disk around HD 34282 and resolve a disk with an inner cavity up to r~90au and a highly structured scattering surface of an inclined disk at a large height H_scat_/r=0.29" above the midplane at the inner edge of the outer disk. Based on the current data it is not possible to conclude decisively whether H_scat_/r remains constant or whether the surface is flared with at most H_scat_ {prop.to} r^1.35^, although we favor the constant ratio based on our deprojections. The height-corrected deprojection allows for a more detailed interpretation of the observed structures, from which we discern the first detection of a single-armed spiral in a protoplanetary disk.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A60
- Title:
- Prominence average magnetic fields in cycle XXI
- Short Name:
- J/A+A/647/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of the present paper is to publish 24 synoptic maps of solar filaments, in which 296 prominence average unambiguous magnetic field vectors were determined by Pic-du-Midi observations between 1974 and 1982, which is the ascending phase of cycle XXI. The magnetic field was determined by interpretation of the Hanle effect observed in the HeI D3 line. Previou the prominence field polarity and prominence chirality were applied to solve the fundamental ambiguity. The meas averaged in each prominence for accuracy reasons. The result is twofold. First, alternating field directions can be observed from one neutral line to the next general field alignment is found along a solar North-South field distorted under the differential rotation effect. The about prominence and their magnetic field coordinates are provided as on-line material associated to this paper.
- ID:
- ivo://CDS.VizieR/J/A+A/591/A101
- Title:
- PSR J1023+0038 & XSS J12270-4859 VRi polarimetry
- Short Name:
- J/A+A/591/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first optical polarimetric study of the two transitional pulsars PSR J1023+0038 and XSS J12270-4859. This work is focused on the search for intrinsically linearly polarised optical emission from the two systems. To this aim, we carried out multiband optical (BVRi) and near-infrared (JHK) photo-polarimetric observations of the two systems using the ESO New Technology Telescope (NTT) at La Silla (Chile), equipped with the EFOSC2 and the SOFI instruments.
