Magnetic propeller effect in the spectra of young stars

Гринин, В. П.; Potravnov, I. S.; Ilyin, I.; Shulman, S. G.

doi:10.1134/s1063773715070014

Cited by 20 publications

(19 citation statements)

References 41 publications

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“…However, there are principal differences between UXORs and the RW Aur A case, namely, a much longer duration and a larger depth of eclipses, higher linear polarization and stability of its orientation during the eclipses. This indicates that if in the case of UXORs the eclipses are produced by relatively small clouds of circumstellar dust (Grinin 1988), then in the case of RW Aur A the eclipses are caused by a much more extended circumstellar dusty environment.…”

Section: Discussionmentioning

confidence: 99%

“…Grinin (1988) and references therein] is clearly seen in the V −Rc, V −Ic colours and possibly present in the B −V colour. It is reasonable to assume that explanations of the effect in both cases are similar: as the star fades, the contribution of more blue light, scattered by the circumstellar dust, increases (Grinin 1988). However, the amplitude (∆V ≈ 5 mag) and duration (several years) of RW Aur A's dimmings are significantly larger than in the case of UXORs, which indicates that in our case, we dealing with suggestive of a larger scale phenomenon than an eclipse of the star by a relatively small dust cloud orbiting the star.…”

Section: Photometrymentioning

confidence: 91%

“…UX Ori (UXOR) type behaviour ['bluing effect', see e.g. Grinin (1988) and references therein] is clearly seen in the V −Rc, V −Ic colours and possibly present in the B −V colour. It is reasonable to assume that explanations of the effect in both cases are similar: as the star fades, the contribution of more blue light, scattered by the circumstellar dust, increases (Grinin 1988).…”

Section: Photometrymentioning

confidence: 99%

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Analysis of colour and polarimetric variability of RW Aur A in 2010–2018

Dodin

Grankin

Ламзин

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Results of U BV RIJHKLM photometry and V RI polarimetry of a young star RW Aur A observed during unprecedented long and deep (up to ∆V ≈ 5 mag) dimming events in 2010-11 and 2014-18 are presented. The polarization degree p of RW Aur A at this period has reached 30 per cent in the I band. As in the case of UX Ori type stars (UXORs), the so-called 'bluing effect' in the colour-magnitude V versus V − R c , V − I c diagrams of the star and a strong anticorrelation between p and brightness were observed. But the duration and the amplitude of the eclipses as well as the value and orientation of polarization vector in our case differ significantly from that of UXORs. We concluded that the dimmings of RW Aur A occurred due to eclipses of the star and inner regions of its disc by the axisymmetric dust structure located above the disc and created by the disc wind. Taking into account both scattering and absorption of stellar light by the circumstellar dust, we explain some features of the light curve and the polarization degree -magnitude dependence. We found that near the period of minimal brightness mass-loss rate of the dusty wind was > 10 −9 M ⊙ yr −1 .

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Section: Discussionmentioning

confidence: 99%

Section: Photometrymentioning

confidence: 91%

Section: Photometrymentioning

confidence: 99%

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Analysis of colour and polarimetric variability of RW Aur A in 2010–2018

Dodin

Grankin

Ламзин

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…These bursts are thought to be triggered by instabilities in the inner parts of the circumstellar disk (D'Angelo & Spruit 2010, 2012Armitage 2016). Observationally, EXor are quite rare systems, with only a few tens of examples known so far (see e.g., Audard et al 2014) and in some cases the classification is uncertain since the observed properties (burst amplitude, cadence, optical/IR colors) are attributable to accretion as well as to extinction episodes related to orbiting dust structures that move along the line of sight (UXors variables, Grinin 1988). These latter are more compatible with repeating brightness variations with the same period and amplitude, while more erratic variations favor the accretion hypothesis.…”

Section: Introductionmentioning

confidence: 99%

The 2016–2017 peak luminosity of the pre-main sequence variable V2492 Cygni

Giannini

Munari

Antoniucci

et al. 2018

A&A

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Context. V2492 Cyg is a young pre-main sequence star presenting repetitive brightness variations of significant amplitude (∆R ≥ 5 mag) whose physical origin has been ascribed to both extinction (UXor-type) and accretion (EXor-type) variability, although their mutual proportion has not been clarified yet. Recently, V2492 Cyg has reached a level of brightness ever registered in the period of its documented activity. Aims. We aim to derive the variation of the mass accretion rate between low-and high-state and to get new insights on the origin of the variability of V2492 Cyg. Methods. Optical and near-infrared photometry and spectroscopy have been obtained in October 2016 and between March and July 2017. The source has remained bright until the end of May 2017, then it started to rapidly fade since the beginning of June at a rate of ∼ 0.08 mag/day. On mid-July 2017 the source has reached the same low-brightness level as two years before. Extinction and mass accretion rate were derived by means of the luminosity of the brightest lines, in particular Hα and Hβ. A couple of optical high-resolution spectra are also presented to derive information on the gas kinematics. Results. Visual extinction variations do not exceed a few magnitudes, while the mass accretion rate is estimated to vary from less than 10 −8 up to a few 10 −7 M ⊙ yr −1 . This latter is comparable to that estimated on the previous high-state in 2010, likely occurred under more severe extinction conditions. Conclusions. The combined analysis of the optical and near-infrared (NIR) observations extends to the present event the original suggestion that the V2492 Cyg variability is a combination of changing extinction and accretion.

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“…Bursts of both classes are thought to be triggered by instabilities originating in the disk itself (Zhu et al 2009, D'Angelo & Spruit 2010, 2012, in particular in the inner connection region between star and disk. To have a more complete account for the scenario of the young variables, UXors objects must also be considered (Grinin 1988), whose brightness variations are related to orbiting dust structures that move along the line of sight.…”

Section: Introductionmentioning

confidence: 99%

Towards a better classification of unclear eruptive variables: the cases of V2492 Cyg, V350 Cep, and ASASSN-15qi

Jurdana-Šepić

Munari

Antoniucci

et al. 2018

A&A

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Context. Eruptive variables are young stars that show episodic variations of brightness: EXors/FUors variations are commonly associated with enhanced accretion outbursts occurring at intermittent cadence of months/years (EXors) and decades/centuries (FUors). Variations that can be ascribed to a variable extinction along their line of sight are instead classified as UXors. Aims. We aim at investigating the long-term photometric behaviour of three sources classified as eruptive variables. We present data from the archival plates of the Asiago Observatory relative to the fields where the targets are located. For the sake of completeness we have also analysed the Harvard plates of the same regions that cover a much longer historical period, albeit at a lower sensitivity, however we are only able to provide upper limits. Methods. A total of 273 Asiago plates were investigated, providing a total of more than 200 magnitudes for the three stars, which cover a period of about 34 yr between 1958 and 1991. We have compared our data with more recently collected literature data.Results. Our plates analysis of V2492 Cyg provides historical upper limits that seem not to be compatible with the level of the activity monitored during the last decade. Therefore, recently observed accretion phenomena could be associated with the outbursting episodes, more than repetitive obscuration. While a pure extinction does not seem the only mechanism responsible for the ASASSN-15qi fluctuations, it can account quite reasonably for the recent V350 Cep variations.

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Magnetic propeller effect in the spectra of young stars

Cited by 20 publications

References 41 publications

Analysis of colour and polarimetric variability of RW Aur A in 2010–2018

Analysis of colour and polarimetric variability of RW Aur A in 2010–2018

The 2016–2017 peak luminosity of the pre-main sequence variable V2492 Cygni

Towards a better classification of unclear eruptive variables: the cases of V2492 Cyg, V350 Cep, and ASASSN-15qi

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