Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/101723
Title: Dynamics of magnetic flux tubes in accretion discs of T Tauri stars
Authors: Dudorov, A. E.
Khaibrakhmanov, S. A.
Sobolev, A. M.
Issue Date: 2019
Publisher: Oxford University Press
Citation: Dudorov A. E. Dynamics of magnetic flux tubes in accretion discs of T Tauri stars / A. E. Dudorov, S. A. Khaibrakhmanov, A. M. Sobolev. — DOI 10.1093/mnras/stz1654 // Monthly Notices of the Royal Astronomical Society. — 2019. — Vol. 487. — Iss. 4. — P. 5388-5404.
Abstract: Dynamics of slender magnetic flux tubes (MFTs) in the accretion discs of T Tauri stars is investigated. We perform simulations taking into account buoyant, aerodynamic, and turbulent drag forces, radiative heat exchange between MFT and ambient gas, and magnetic field of the disc. The equations of MFT dynamics are solved using Runge-Kutta method of the fourth order. The simulations show that there are two regimes of MFT motion in absence of external magnetic field. In the region r < 0.2 au, the MFTs of radii 0.05 ≤ a0 ≤ 0.16, H (H is the scale height of the disc) with initial plasma beta of 1 experience thermal oscillations above the disc. The oscillations decay over some time, and MFTs continue upward motion afterwards. Thinner or thicker MFTs do not oscillate. MFT velocity increases with initial radius and magnetic field strength. MFTs rise periodically with velocities up to 5-15 km s-1 and periods of 0.5-10 yr determined by the toroidal magnetic field generation time. Approximately 20 per cent of disc mass and magnetic flux can escape to disc atmosphere via the magnetic buoyancy over characteristic time of disc evolution. MFTs dispersal forms expanding magnetized corona of the disc. External magnetic field causes MFT oscillations near the disc surface. These magnetic oscillations have periods from several days to 1-3 months at r < 0.6 au. The magnetic oscillations decay over few periods. We simulate MFT dynamics in accretion discs in the Chameleon I cluster. The simulations demonstrate that MFT oscillations can produce observed IR-variability of T Tauri stars. © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
Keywords: ACCRETION, ACCRETION DISCS
DIFFUSION
ISM: JETS AND OUTFLOWS
ISM: MAGNETIC FIELDS
MHD
STARS: VARIABLES: T TAURI, HERBIG AE/BE
URI: http://hdl.handle.net/10995/101723
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85070070693
PURE ID: 10287498
b9b86628-2d51-445c-8b7f-bad21ccb1386
ISSN: 358711
DOI: 10.1093/mnras/stz1654
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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