Interstellar Polarization in the Southern Milky way.

Smith, Elske V. P.

doi:10.1086/146202

Cited by 21 publications

(13 citation statements)

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“… Photopolarimetry sources: (1) Guetter & Vrba (1989); (2) Hiltner (1956); (3) Klare & Neckel (1977); (4) Kobulnicky et al (1994); (5) Lupie & Nordsieck (1987); (6) McMillan & Tapia (1977, O ≃ R ); (7) Östreicher & Schulte‐Ladbeck (1982); (8) Serkowski (1965); (9) Serkowski (1968); (10) Serkowski et al (1975); (11) Serkowski & Roberston (1969); (12) van Smith (1956, wavelength unspecified); (13) Whittet et al (1992). …”

Section: Observed Polarizationmentioning

confidence: 99%

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Spectropolarimetry of O supergiants

Harries¹,

Howarth²,

Evans³

2002

Monthly Notices of the Royal Astronomical Society

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We present medium-resolution spectropolarimetry at high signal-to-noise ratio of the Hα emission line of 20 O-type supergiants. Five stars (25 per cent) of the sample show a statistically significant change in polarization through the line.We combine our Hα data with new K-band spectropolarimetry and archival low-resolution optical spectropolarimetry to determine the polarigenic mechanism in the stars that show a line effect. We show that the line polarization change in the binary systems is caused by the classical 'dilution' mechanism, in which the Hα emission is essentially unpolarized and the continuum polarization is caused by intrabinary scattering. We find that the line effect in HD 108 is also well modelled by pure dilution, but suggest that the continuum polarization is the result of stochastic wind clumping. A similar description applies to the continuum polarization of HD 188001, although the line effect cannot be reproduced by pure dilution. We use low-resolution spectropolarimetry to determine the interstellar polarization vector to λ Cephei, and confirm that the intrinsic polarization of the object is very low (<0.1 per cent, corresponding to an equator:pole density ratio of <1.25). The line polarization of this star is modelled using the TORUS three-dimensional radiative-transfer code. We show that the line effect is a consequence of symmetry breaking caused by the rapid rotation of the system (>200 km s −1 ), and that the system is similar polarimetrically to the O4 supergiant ζ Puppis.Finally, we note that the precision of current photo-and spectro-polarimetric observations is insufficient to test structured wind models, which predict a continuum polarization of ∼0.1 per cent.

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Section: Observed Polarizationmentioning

confidence: 99%

“… 1 We have converted polarizations in the older literature, expressed in magnitudes, to percentage polarizations using p (per cent) =100 ×[(10 0.4 p (Δ m ) − 1)/2] ; however, this does not precisely reproduce Hiltner's transformations, which appear to be simply linear [ p (per cent) =46 p (Δ m ) ; see also van Smith 1956 . ] …”

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confidence: 99%

Spectropolarimetry of O supergiants

Harries¹,

Howarth²,

Evans³

2002

Monthly Notices of the Royal Astronomical Society

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“…µ 1 Sco is a semi-detached binary where the secondary is close to or just filling its Roche lobe (van Antwerpen & Moon 2010;Budding et al 2015). According to Budding et al (2015) the secondary's over-sized character implies on-going late-state interactive stellar evolution, believed to be of the 'Case A' type (i.e.…”

Section: µ 1 Scomentioning

confidence: 99%

“…Despite being labelled as "Variable" in SIMBAD 6 µ 2 Sco is not considered so by most observers, and is frequently used as a constant check star in observations of µ 1 Sco (van Antwerpen & Moon 2010; Handler & Schwarzenberg-Czerny 2013). It was the subject of two unfiltered 7 polarimetric observations by van Smith (1956) giving an average p = 4605 ± ∼<1302 ppm 5 , P A = 25 ± 4 • . That these values are the same as those of µ 1 Sco within error suggests that the majority of the polarization is interstellar in origin.…”

Section: µ 1 Scomentioning

confidence: 99%

Phase-locked polarization by photospheric reflection in the semidetached eclipsing binary μ1 Sco

Cotton

Bailey

Kedziora-Chudczer

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We report the detection of phase-locked polarization in the bright (mV = 2.98 − 3.24) semidetached eclipsing binary μ1 Sco (HD 151890). The phenomenon was observed in multiple photometric bands using two different HIPPI-class (HIgh Precision Polarimetric Instrument) polarimeters with telescopes ranging in size from 35-cm to 3.9-m. The peak-to-trough amplitude of the polarization is wavelength dependent and large, ∼700 parts-per-million in green light, and is easily seen with even the smallest telescope. We fit the polarization phase curve with a SYNSPEC/VLIDORT polarized radiative transfer model and a Wilson-Devinney geometric formalism, which we describe in detail. Light from each star reflected by the photosphere of the other, together with a much smaller contribution from tidal distortion and eclipse effects, wholly accounts for the polarization amplitude. In the past polarization in semidetached binaries has been attributed mostly to scattering from extra-stellar gas. Our new interpretation facilitates determining masses of such stars in non-eclipsing systems.

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“…Measuring optical polarization is a powerful method for probing the geometry and composition of dust in galaxies because the data contain directional and intensity information (Hall 1949;Hiltner 1949;Whittet 2003). Polarization studies have been done on a variety of objects, including stars in the Milky Way (MW) (Heiles 2000;van Smith 1956;Mathewson & Ford 1970), accretion disks around black holes (Antonucci 1984;Stockman et al 1984;Wills et al 1992;Brindle et al 1990), and young stellar objects (Bastien & Menard 1990). Measuring optical polarization of galaxies is a key way to learn more about their dust and magnetic field properties.…”

Section: Introductionmentioning

confidence: 99%

Integrated Optical Polarization of Nearby Galaxies

Jones

Wang

Krisciunas

et al. 2012

ApJ

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We performed an integrated optical polarization survey of 70 nearby galaxies to study the relationship between linear polarization and galaxy properties. To date this is the largest survey of its kind. The data were collected at McDonald Observatory using the Imaging Grism Polarimeter on the Otto Struve 2.1m telescope. Most of the galaxies did not have significant level of linear polarization, where the bulk is < 1%. A fraction of the galaxies showed a loose correlation between the polarization and position angle of the galaxy, indicating that dust scattering is the main source of optical polarization. The unbarred spiral galaxies are consistent with the predicted relationship with inclination from scattering models of ∼ sin 2 i.

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Interstellar Polarization in the Southern Milky way.

Cited by 21 publications

References 0 publications

Spectropolarimetry of O supergiants

Spectropolarimetry of O supergiants

Phase-locked polarization by photospheric reflection in the semidetached eclipsing binary μ1 Sco

Integrated Optical Polarization of Nearby Galaxies

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