Magnetic field buoyancy in accretion disks of young stars

TL;DR

This paper investigates how magnetic buoyancy, driven by Parker instability, influences the strength and behavior of magnetic fields in accretion disks around young stars, particularly T Tauri stars.

Contribution

It introduces a model incorporating buoyancy as a flux escape mechanism and calculates magnetic field intensities considering flux tube sizes in young star disks.

Findings

Buoyancy limits the growth of toroidal magnetic fields.

Magnetic field strength becomes comparable to vertical fields for small flux tubes.

The model explains magnetic field regulation in young stellar accretion disks.

Abstract

Buoyancy of the fossil magnetic field in the accretion disks of young stars is investigated. It is assumed that the Parker instability leads to the formation of slender flux tubes of toroidal magnetic field in the regions of effective magnetic field generation. Stationary solution of the induction equation is written in the form in which buoyancy is treated as the additional mechanism of the magnetic flux escape. We calculate the fossil magnetic field intensity in the accretion disks of young T Tauri stars for the cases when radius of the magnetic flux tubes $a_{\mathrm{mft}} = 0.1H$, $0.5 H$ or $1H$, where $H$ is the accretion disk height scale. Calculations show that the buoyancy limits toroidal magnetic field growth, so that its strength is comparable with the vertical magnetic field strength for the case $a_{\mathrm{mft}}=0.1H$.