Influence of Large-Scale Perturbations in Circumstellar Disks on the Linear Polarization Parameters of UX Ori Stars

Shulman, S. G.; Гринин, В. П.

doi:10.1134/s1063773719100062

Cited by 7 publications

(3 citation statements)

References 36 publications

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“…In our previous paper (Shulman & Grinin 2019b), round hump did not give us 90°positional angle change during the eclipse. Herewith the maximum deviation of the positional angle was achieved after the eclipse, and not during it, as in the above examples.…”

Section: Eclipse Phase Dependencementioning

confidence: 72%

“…Similar geometry of the hump was previously used in O' Sullivan et al (2005) for AA Tau photopolarimetry modelling. In our previous work (Shulman & Grinin 2019b) we used a simpler hump model, determining its shape only by distance from the hump centre. Below the hump is described in the polar coordinate ( = 2 + 2 , = arctan( / )) system with the equation:…”

Section: Disc Humpmentioning

confidence: 99%

“…In our paper (Shulman & Grinin 2019b) we calculated such eclipses for the first time for a flared disc model and a disc with the puffing-up in the inner region. We used as a screen a simple 1-D model of the disc perturbation.…”

Section: Introductionmentioning

confidence: 99%

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UX Ori Stars Eclipses by Large-Scale Disc Perturbations

Shulman,

Grinin

2021

Preprint

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The eclipses of UX Ori type stars by large-scale disc humps are studied in detail. The influence of the hump extension on the eclipse depth and parameters of the linear polarization is modelled and compared with a compact cloud eclipse model. Eclipses were investigated both for the flared disc and for the disc with a puffing-up in the dust sublimation zone. It is shown that the large-scale hump eclipse may be significantly deeper than a compact cloud eclipse and show a greater linear polarization degree compared to it. It is also demonstrated that the hump extension together with the disc puffing-up can strongly affect the degree of polarization and colour index of the star during the eclipse. The position angle of the linear polarization may also change markedly during and after an eclipse by a large scale hump for the model with a puffed-up inner rim. Also, in this model, the maximum degree of the linear polarization can be achieved not at the brightness minimum, but closer to the end of the eclipse.

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Section: Eclipse Phase Dependencementioning

confidence: 72%

Section: Disc Humpmentioning

confidence: 99%

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UX Ori Stars Eclipses by Large-Scale Disc Perturbations

Shulman,

Grinin

2021

Preprint

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UX Ori stars eclipses by large-scale disc perturbations

Shulman

Гринин

2022

Monthly Notices of the Royal Astronomical Society

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We simulate the polarized radiative transfer in vicinities of the UX Ori type stars during their minima. Our model of an eclipse by an extended disc perturbation generalizes the compact gas-dust cloud eclipse model. We apply the radiative transfer method based on enumeration using the directions grid to model the influence of the perturbation extensions along azimuth and radius on the eclipse depth and parameters of the linear polarization. We investigate eclipses both for the flared disc and for the disc with a puffing-up in the dust sublimation zone. The puffing-up is obtained by adding a disc wind to the model. Comparison with a compact cloud eclipse model reveals that the eclipse by a large-scale azimuthally extended perturbation may be significantly deeper and show a greater linear polarization degree. We also demonstrate that the perturbation extension together with the disc puffing-up can strongly affect the degree of polarization and colour index of the star during the eclipse. The position angle of the linear polarization may also change markedly during and after an eclipse by a large scale perturbation for the model with a puffed-up inner rim. Also, in this model, the maximum degree of the linear polarization can be achieved not at the brightness minimum but closer to the end of the eclipse. We discuss the modelling results in the context of the photopolarimetric observations of UX Ori stars.

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Modelling UX Ori star eclipses based on spectral observations with the Nordic Optical Telescope − I. RR Tau

Grinin,

Tambovtseva,

Djupvik

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Based on observations obtained with the Nordic Optical Telescope (NOT) we investigate the spectral variability of the Herbig Ae star RR Tau. This star belongs to the UX Ori family, characterized by very deep fadings caused by the screening of the star with opaque fragments (clouds) of the protoplanetary discs. At the moments of such minima one observes strong spectral variability due to the fact that the dust cloud occults, for an observer, not only the star but also a part of the region where the emission spectrum originates. We calculated a series of obscuration models to interpret the observed variability of the H α line parameters. We consider two main obscuration scenarios: (1) the dust screen rises vertically above the circumstellar disc, and (2) the screen intersects the line-of-sight moving azimuthally with the disc. In both cases, the model of the emission region consists of a compact magnetosphere and a magnetocentrifugal disc wind. Comparison with observations shows that the first scenario explains well the variability of the radiation flux, the equivalent width, as well as the asymmetry of the H α line during eclipses, while the second scenario explains them only partly. This permits us to suggest that in the case of RR Tau, the main causes of the eclipses are either a structured disc wind, or the charged dust lifted along the field lines of the poloidal component of the magnetic field of the circumstellar disc.

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Influence of Large-Scale Perturbations in Circumstellar Disks on the Linear Polarization Parameters of UX Ori Stars

Cited by 7 publications

References 36 publications

UX Ori Stars Eclipses by Large-Scale Disc Perturbations

UX Ori Stars Eclipses by Large-Scale Disc Perturbations

UX Ori stars eclipses by large-scale disc perturbations

Modelling UX Ori star eclipses based on spectral observations with the Nordic Optical Telescope − I. RR Tau

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