TY - JOUR

T1 - Dynamics of magnetic flux tubes in accretion disks of Herbig Ae/Be stars

AU - Khaibrakhmanov, Sergey A.

AU - Dudorov, Alexander E.

PY - 2022/1/1

Y1 - 2022/1/1

N2 - The dynamics of magnetic flux tubes (MFTs) in the accretion disk of typical Herbig Ae/Be star (HAeBeS) with fossil large-scale magnetic field is modeled taking into account the buoyant and drag forces, radiative heat exchange with the surrounding gas, and the magnetic field of the disk. The structure of the disk is simulated using our magnetohydrodynamic model, taking into account the heating of the surface layers of the disk with the stellar radiation. The simulations show that MFTs periodically rise from the innermost region of the disk with speeds up to 10-12 km s - 1 {{\rm{s}}}^{-1}. MFTs experience decaying magnetic oscillations under the action of the external magnetic field near the disk's surface. The oscillation period increases with distance from the star and initial plasma beta of the MFT, ranging from several hours at r = 0.012 au r=0.012\hspace{0.33em}{\rm{au}} up to several months at r = 1 au r=1\hspace{0.33em}{\rm{au}}. The oscillations are characterized by pulsations of the MFT's characteristics including its temperature. We argue that the oscillations can produce observed IR-variability of HAeBeSs, which would be more intense than in the case of T Tauri stars, since the disks of HAeBeSs are hotter, denser, and have stronger magnetic field.

AB - The dynamics of magnetic flux tubes (MFTs) in the accretion disk of typical Herbig Ae/Be star (HAeBeS) with fossil large-scale magnetic field is modeled taking into account the buoyant and drag forces, radiative heat exchange with the surrounding gas, and the magnetic field of the disk. The structure of the disk is simulated using our magnetohydrodynamic model, taking into account the heating of the surface layers of the disk with the stellar radiation. The simulations show that MFTs periodically rise from the innermost region of the disk with speeds up to 10-12 km s - 1 {{\rm{s}}}^{-1}. MFTs experience decaying magnetic oscillations under the action of the external magnetic field near the disk's surface. The oscillation period increases with distance from the star and initial plasma beta of the MFT, ranging from several hours at r = 0.012 au r=0.012\hspace{0.33em}{\rm{au}} up to several months at r = 1 au r=1\hspace{0.33em}{\rm{au}}. The oscillations are characterized by pulsations of the MFT's characteristics including its temperature. We argue that the oscillations can produce observed IR-variability of HAeBeSs, which would be more intense than in the case of T Tauri stars, since the disks of HAeBeSs are hotter, denser, and have stronger magnetic field.

KW - accretion discs

KW - Herbig Ae/Be

KW - ISM: magnetic fields

KW - MHD

KW - stars: variables: T Tauri

UR - http://www.scopus.com/inward/record.url?scp=85127911284&partnerID=8YFLogxK

U2 - 10.1515/astro-2022-0017

DO - 10.1515/astro-2022-0017

M3 - Article

AN - SCOPUS:85127911284

VL - 31

SP - 125

EP - 135

JO - Open Astronomy

JF - Open Astronomy

SN - 2543-6376

IS - 1

ER -