- ID:
- ivo://CDS.VizieR/J/ApJ/665/369
- Title:
- Photopolarimetry of Southern Coalsack stars
- Short Name:
- J/ApJ/665/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new multicolor photopolarimetry of stars behind the Southern Coalsack. Analyzed together with multiband polarization data from the literature, probing the Chamaeleon I, Musca, rho Opiuchus, R CrA, and Taurus clouds, we show that the wavelength of maximum polarization ({lambda}_max_) is linearly correlated with the radiation environment of the grains. Using far-infrared emission data, we show that the large scatter seen in previous studies of {lambda}_max_ as a function of Av is primarily due to line-of-sight effects causing some Av measurements to not be a good tracer of the extinction (radiation field strength) seen by the grains being probed.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/369/449
- Title:
- PKS 0405-385 flux-density monitoring
- Short Name:
- J/MNRAS/369/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The quasar PKS 0405-385 is one of three radio sources (the other two are PKS 1257-326 and J1819+385) which exhibit unusually strong and rapid interstellar scintillations at GHz frequencies. Such a behaviour suggests a nearby (<30pc away) scattering screen along the line of sight to these radio sources. While quasars PKS 1257-326 and J1819+385 scintillate continuously over several years of monitoring, PKS 0405-385 shows episodes of strong scintillations which last only a few months. Here, I present the results of flux-density monitoring of PKS 0405-385 over 6yr at four Stokes parameters and four frequencies. Two explanations of the episodic behaviour of interstellar scintillation in this source are discussed; morphological evolution of the source and changes in the properties of the interstellar medium along the line of sight.
- ID:
- ivo://CDS.VizieR/J/other/PASA/37.29
- Title:
- POGS-II ExGal catalog
- Short Name:
- J/other/PASA/37.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The low-frequency linearly polarised radio source population is largely unexplored. However, a renaissance in low-frequency polarimetry has been enabled by pathfinder and precursor instruments for the Square Kilometre Array. In this second paper from the POlarised GaLactic and Extragalactic All-Sky MWA Survey-the POlarised GLEAM Survey, or POGS-we present the results from our all-sky MWA Phase I Faraday Rotation Measure survey. Our survey covers nearly the entire Southern sky in the Declination range -82{deg} to +30{deg} at a resolution between around three and seven arcminutes (depending on Declination) using data in the frequency range 169-231MHz. We have performed two targeted searches: the first covering 25489 square degrees of sky, searching for extragalactic polarised sources; the second covering the entire sky South of Declination +30{deg}, searching for known pulsars. We detect a total of 517 sources with 200MHz linearly polarised flux densities between 9.9mJy and 1.7Jy, of which 33 are known radio pulsars. All sources in our catalogues have Faraday rotation measures in the range -328.07rad/m^2^ to +279.62rad/m^2^. The Faraday rotation measures are broadly consistent with results from higher-frequency surveys, but with typically more than an order of magnitude improvement in the precision, highlighting the power of low-frequency polarisation surveys to accurately study Galactic and extragalactic magnetic fields. We discuss the properties of our extragalactic and known-pulsar source population, how the sky distribution relates to Galactic features, and identify a handful of new pulsar candidates among our nominally extragalactic source population.
- ID:
- ivo://CDS.VizieR/J/PASP/126/469
- Title:
- PolarBase catalogue of stellar spectra
- Short Name:
- J/PASP/126/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PolarBase is an evolving data base that contains all stellar data collected with the ESPaDOnS and NARVAL high-resolution spectropolarimeters, in their reduced form, as soon as they become public. As of early 2014, observations of 2,000 stellar objects throughout the Hertzsprung-Russell diagram are available. Intensity spectra are available for all targets, and the majority of the observations also include simultaneous spectra in circular or linear polarization, with the majority of the polarimetric measurements being performed only in circularly polarized light (Stokes V). Observations are associated with a cross-correlation pseudo-line profile in all available Stokes parameters, greatly increasing the detectability of weak polarized signatures. Stokes V signatures are detected for more than 300 stars of all masses and evolutionary stages, and linear polarization is detected in 35 targets. The detection rate in Stokes V is found to be anti-correlated with the stellar effective temperature. This unique set of Zeeman detections offers the first opportunity to run homogeneous magnetometry studies throughout the H-R diagram. The web interface of PolarBase is available at http://polarbase.irap.omp.eu.
- ID:
- ivo://CDS.VizieR/B/polarbase
- Title:
- PolarBase spectropolarimetric database (ESPaDOnS, NARVAL)
- Short Name:
- B/polarbase
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PolarBase is an evolving data base that contains all stellar data collected with the ESPaDOnS and NARVAL high-resolution spectropolarimeters, in their reduced form, as soon as they become public. As of early 2014, observations of 2,000 stellar objects throughout the Hertzsprung-Russell diagram are available. Intensity spectra are available for all targets, and the majority of the observations also include simultaneous spectra in circular or linear polarization, with the majority of the polarimetric measurements being performed only in circularly polarized light (Stokes V). Observations are associated with a cross-correlation pseudo-line profile in all available Stokes parameters, greatly increasing the detectability of weak polarized signatures. Stokes V signatures are detected for more than 300 stars of all masses and evolutionary stages, and linear polarization is detected in 35 targets. The detection rate in Stokes V is found to be anti-correlated with the stellar effective temperature. This unique set of Zeeman detections offers the first opportunity to run homogeneous magnetometry studies throughout the H-R diagram. The web interface of PolarBase is available at http://polarbase.irap.omp.eu.
- ID:
- ivo://CDS.VizieR/J/other/NatAs/6.154
- Title:
- Polarimetric asteroseismology of beta Crucis
- Short Name:
- J/other/NatAs/6.
- Date:
- 31 Jan 2022 09:03:48
- Publisher:
- CDS
- Description:
- Here we report the detection of polarization variations due to nonradial modes in the {beta} Cephei star {beta} Crucis. In so doing we confirm 40- year-old predictions of pulsation-induced polarization variability and its utility in asteroseismology for mode identification. In an approach suited to other {beta} Cephei stars, we combine polarimetry with space-based photometry and archival spectroscopy to identify the dominant nonradial mode in polarimetry, f2, as l=3, m=-3 (in the m-convention of Dziembowski, 1977AcA.....27..203D) and determine the stellar axis position angle as 25 (or 205) +/-8 degrees. The rotation axis inclination to the line of sight was derived as approx. 46 degrees from combined polarimetry and spectroscopy, facilitating identification of additional modes and allowing for asteroseismic modelling. This reveals a star of 14.5+/-0.5M_{sun}_ and a convective core containing approx. 28 percent of its mass - making {beta} Crucis the most massive star with an asteroseismic age.
- ID:
- ivo://CDS.VizieR/J/A+A/489/911
- Title:
- Polarimetric measures of selected variable stars
- Short Name:
- J/A+A/489/911
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The purpose of this paper is to summarize and interpret unpublished optical polarimetry for numerous program stars that were observed over the past decades at the Flower and Cook Observatory (FCO), University of Pennsylvania. We also make the individual calibrated measures available for long-term comparisons with new data. We employ three techniques to search for intrinsic variability within each dataset. First, when the observations for a given star and filter are numerous enough and when a period has been determined previously via photometry or spectroscopy, the polarimetric measures are plotted versus phase. If a statistically significant pattern appears, we attribute it to intrinsic variability. Second, we compare means of the FCO data to means from other workers. If they are statistically different, we conclude that the object exhibits long-term intrinsic variability. Third, we calculate the standard deviation for each program star and filter and compare it to the standard deviation estimated from comparable polarimetric standards. If the standard deviation of the program star is at least three times the value estimated from the polarimetric standards, the former is considered intrinsically variable. All of these statements are strengthened when variability appears in multiple filters.
- ID:
- ivo://CDS.VizieR/J/AZh/71/717
- Title:
- Polarimetric Observations of BL Lac
- Short Name:
- J/AZh/71/717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper continues publications that report the results of photoelectric polarization measurements of the blazar BL Lac. Earlier, we published observational data obtained over the period 1969-1982 (Hagen-Torn et al., 1984AZh....61..925H). Here, we discuss the observations over the period 1983-1991.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A86
- Title:
- Polarimetric survey of main-belt asteroids
- Short Name:
- J/A+A/529/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a polarimetric survey of main-belt asteroids at Complejo Astronomico El Leoncito (Casleo), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties, similar to those shown by the asteroid (234) Barbara. The data were obtained with the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows the simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation.
- ID:
- ivo://CDS.VizieR/J/ApJ/864/L33
- Title:
- Polarimetric survey of Phaethon with PICO
- Short Name:
- J/ApJ/864/L33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a function of the solar phase angle, {alpha}, the linear polarization degree (referred to the scattering plane, P_r_) of solar system objects is a good diagnostic for understanding the scattering properties of their surface materials. We report the P_r_ of Phaethon over a wide range of {alpha} from 19.1{deg} to 114.3{deg}. The derived phase-polarization curve shows that the maximum of P_r_, Pmax, is >42.4% at {alpha}>114.3{deg}, a value significantly larger than those of the moderate albedo asteroids (Pmax~9%). The phase-polarization curve classifies Phaethon as B-type as well as M- and K-type asteroids, in the polarimetric taxonomy, being compatible with the spectral property. We compute the geometric albedo, p_v_, of 0.14+/-0.04 independently by using an empirical slope-albedo relation, and the derived p_v_ is consistent with previous results determined from mid-infrared spectra and thermophysical modeling. We find no periodic variation of P_r_ in our polarimetric data in the range from 0 up to 7.208hr (e.g., less than twice the rotational period). We also find significant differences between our P_r_ during the 2017 approach toward Earth and that in 2016, implying that Phaethon has a region with different properties for light scattering near its rotational pole.
