Influence of Ohmic and ambipolar heating on the thermal structure of accretion discs

S. A. Khaibrakhmanov^{1, 2} - A. E. Dudorov²

¹ Ural Federal University, 51 Lenin str., Ekaterinburg 620000, Russia
² Chelyabinsk State University, 129 Br. Kashirinykh str., Chelyabinsk 454001, Russia

Abstract
Dynamics of accretion discs of young stars with a fossil large-scale magnetic field are investigated. The presented magneto-gas-dynamic (MHD) model of accretion discs includes the equations of Shakura and Sunyaev, induction equation, equations of thermal and collisional ionization. The induction equation takes into account Ohmic and magnetic ambipolar diffusion, magnetic buoyancy. The influence of Ohmic and ambipolar heating on the thermal structure of accretion discs is considered, and the influence of the considered dissipative MHD effects on the temperature of the accretion discs around the classical T Tauri star is analyzed. Simulations show that Ohmic and ambipolar heating operates near the borders of the region with a low ionization fraction (`dead' zone). The temperature grows by  ∼ 1000 K near the inner boundary of the `dead' zone, r ≈ (0.5−1) AU, and by  ∼ 100 K near its outer boundary, r ≈ (30−50) AU. Figs 3, Refs 26.