PV CEP and V350 CEP: Stars on the Way between FUors and EXors

Andreasyan, H. R.; Magakian, T. Yu.; Movsessian, T. A.; Моисеев, А. В.

doi:10.1007/s10511-021-09680-5

“…PV Cep and DR Tau were originally included in the first list of EXor variables by Herbig (1989). PV Cep repeatedly undergoes intense outbursts (up to 5 mag) of short duration and brightness between that of FUors and EXors (Andreasyan et al 2021). Its high luminosity (≈100 L e ) is likely attributable to a young Herbig Ae star (see e.g., Lorenzetti et al 2011).…”

Section: The Investigated Samplementioning

confidence: 99%

“…For these reasons Herbig (2008) did not classify V350 Cep as an EXor. Considering its high and stable brightness level and its spectrum rich in emission lines, it is likely that also V350 Cep is an object with properties in between those of FUors and EXors (Andreasyan et al 2021). iPTF15afq is a new candidate EXor, suggested by Miller et al (2015) on the basis of the amplitude of its outburst of about 2.5 mag (in R-band) and its spectrum dominated by lines in emission.…”

Section: The Investigated Samplementioning

confidence: 99%

EXORCISM: A Spectroscopic Survey of Young Eruptive Variables (EXor and Candidates)

Giannini

¹

,

Giunta

²

,

Gangi

³

et al. 2022

ApJ

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We present an optical/near-IR survey of 11 variable young stars (EXors and EXor candidates) aimed at deriving and monitoring their accretion properties. About 30 optical and near-infrared spectra ( R ∼ 1500 – 2000 ) were collected between 2014 and 2019 with the Large Binocular Telescope (LBT). From the spectral analysis we have derived the accretion luminosity (L acc ) and mass accretion rate ( M ̇ acc ), the visual extinction (A V), the temperature and density of the permitted line formation region (T, n H), and the signature of the outflowing matter. Two sources (ASASSN-13db and iPTF15afq) have been observed in outburst and quiescence, three during a high level of brightness (XZ Tau, PV Cep, and NY Ori), and the others in quiescence. These latter have L acc and M ̇ acc in line with the values measured in classical T Tauri stars of similar mass. All sources observed more than once present L acc and M ̇ acc variability. The most extreme case is ASASSN-13db, for which M ̇ acc decreases by two orders of magnitude from the outburst peak in 2015 to quiescence in 2017. Also, in NY Ori L acc decreases by a factor 25 in one year. In 80% of the sample we detect the [O i] 6300 Å line, a tracer of mass loss. From the variability of the Hα/[O i] 6300 Å ratio, we conclude that mass accretion variations are larger than mass loss variations. From the analysis of the H i recombination lines, a correlation is suggested between the density of the line formation region, and the level of accretion activity of the source.

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“…PV Cep and DR Tau were originally included in the first list of EXor variables by Herbig (1989). PV Cep repeatedly undergoes intense outbursts (up to 5 mag) of short duration and brightness between that of FUors and EXors (Andreasyan et al 2021). Its high luminosity (≈ 100 L ) is likely attributable to a young Herbig Ae star (see e.g.…”

Section: The Investigated Samplementioning

confidence: 99%

“…For these reasons Herbig (2008) did not classify V350 Cep as an EXor. Considering its high and stable brightness level and its spectrum rich in emission lines, it is likely that also V350 Cep is an object with properties in between those of FUors and EXors (Andreasyan et al 2021). iPTF15afq is a new candidate EXor, suggested by Miller et al (2015) on the basis of the amplitude of its outburst of about 2.5 mag (in R-band) and its spectrum dominated by lines in emission.…”

Section: The Investigated Samplementioning

confidence: 99%

EXORCISM: a spectroscopic survey of young eruptive variables (EXor and candidates)

Giannini,

Giunta,

Gangi

et al. 2022

Preprint

0

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We present an optical/near-IR survey of 11 variable young stars (EXors and EXor candidates) aimed at deriving and monitoring their accretion properties. About 30 optical and near-infrared spectra ( ∼ 1500-2000) were collected between 2014-2019 with the Large Binocular Telescope (LBT). From the spectral analysis we have derived the accretion luminosity (L acc ) and mass accretion rate ( Ṁacc ), the visual extinction (A V ) , the temperature and density of the permitted line formation region (T, n H ), and the signature of the outflowing matter.Two sources (ASASSN-13db and iPTF15afq) have been observed in outburst and quiescence, three during a high-level of brightness (XZ Tau, PV Cep, and NY Ori), and the others in quiescence. These latter have L acc and Ṁacc in line with the values measured in classical T Tauri stars of similar mass. All sources observed more than once present L acc and Ṁacc variability. The most extreme case is ASASSN-13db, for which Ṁacc decreases by two orders of magnitude from the outburst peak in 2015 to quiescence in 2017. Also, in NY Ori L acc decreases by a factor 25 in one year. In 80% of the sample we detect the [O I] 6300 Å line, a tracer of mass loss. From the variability of the Hα/[O I] 6300 Å ratio, we conclude that mass accretion variations are larger than mass loss variations. From the analysis of the H I recombination lines a correlation is suggested between the density of the line formation region, and the level of accretion activity of the source.

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“…It can describe the magnetic field in the accretion disc surrounding the central black hole in this object. The next important example is connected with the accretion discs which are associated with eruptive stars Andreasyan et al (2021).…”

Section: Introductionmentioning

confidence: 99%

No-z model: results and perspectives for accretion discs

Михайлов

¹

,

Pashentsevay

²

2021

ComBAO

0

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Accretion discs surround different compact astrophysical objects such as black holes, neutron stars and white dwarfs. Also they are situated in systems of variable stars and near the galaxy center. Magnetic fields play an important role in evolution and hydrodynamics of the accretion discs: for example, they can describe such processes as the transition of the angular momentum. There are different approaches to explain the magnetic fields, but most interesting of them are connected with dynamo generation. As for disc, it is quite useful to take no-$z$ approximation which has been developed for galactic discs to solve the dynamo equations. It takes into account that the disc is quite thin, and we can solve the equations only for two plane components of the field. Here we describe the time dependence of the magnetic field for different distances from the center of the disc. Also we compare the results with another approaches which take into account more complicated field structure.

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PV CEP and V350 CEP: Stars on the Way between FUors and EXors

Cited by 5 publications

References 31 publications

EXORCISM: A Spectroscopic Survey of Young Eruptive Variables (EXor and Candidates)

EXORCISM: A Spectroscopic Survey of Young Eruptive Variables (EXor and Candidates)

EXORCISM: a spectroscopic survey of young eruptive variables (EXor and candidates)

No-z model: results and perspectives for accretion discs

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