We simulate the dynamics of slender magnetic flux tubes （MFTs） in the accretion disks of T Tauri stars. The dynamical equations of our model take into account aerodynamic and turbulent drag forces, and the radiative...We simulate the dynamics of slender magnetic flux tubes （MFTs） in the accretion disks of T Tauri stars. The dynamical equations of our model take into account aerodynamic and turbulent drag forces, and the radiative heat exchange between the MFT and ambient gas. The structure of the disk is calculated with the help of our MHD model of the accretion disks. We consider the MFTs formed at distances of 0.027 - 0.8 au from the star with various initial radii and plasma betas β0. The simulations show that MFTs with a weak magnetic field （β0 = 10） rise slowly with speeds less than the speed of sound. MFTs withβ0 = 1 form an outflowing magnetized corona above the disk. Strongly magnetized MFTs （β0 = 0.1） can cause outflows with velocities 20 - 50 km s-1. The tubes rise periodically over times from several days to several months according to our simulations. We propose that periodically rising MFTs can absorb stellar radiation and contribute to the IR-variability of young stellar objects.展开更多
The problem of determining the masses and ages of T Tauri star （TTS） using their evolu- tionary status is discussed. We test four pre-main sequence evolutionary models using well determined observational parameters ...The problem of determining the masses and ages of T Tauri star （TTS） using their evolu- tionary status is discussed. We test four pre-main sequence evolutionary models using well determined observational parameters of 12 binary TTSs and two binary red dwarfs. It is shown that the masses derived using the tracks of all models are in good agreement with flhe masses obtained from the obser- vations of TTSs with masses M 〉 0.7 Me （mean error ε,- 10%）. Low-mass stars with M ≤ 0.7 M⊙ have significantly greater mean error; e - 50% for the tracks of Bressan et al. and Chen et al., and e - 30% for the other tracks. The isochrones of all tested evolutionary models diverge for stars with masses M ≤ 0.7 M⊙. The difference increases with the mass decrease and can reach 10% of Kelvin- Helmholtz time for stars with mass M = 0.2 Me. The ages of most of the considered TTSs are smaller than the Kelvin-Helmholtz time. This confirms their evolutionary status of being pre-main sequence stars.展开更多
基金supported by Russian Foundation for Basic Research(project 18-02-01067)
文摘We simulate the dynamics of slender magnetic flux tubes （MFTs） in the accretion disks of T Tauri stars. The dynamical equations of our model take into account aerodynamic and turbulent drag forces, and the radiative heat exchange between the MFT and ambient gas. The structure of the disk is calculated with the help of our MHD model of the accretion disks. We consider the MFTs formed at distances of 0.027 - 0.8 au from the star with various initial radii and plasma betas β0. The simulations show that MFTs with a weak magnetic field （β0 = 10） rise slowly with speeds less than the speed of sound. MFTs withβ0 = 1 form an outflowing magnetized corona above the disk. Strongly magnetized MFTs （β0 = 0.1） can cause outflows with velocities 20 - 50 km s-1. The tubes rise periodically over times from several days to several months according to our simulations. We propose that periodically rising MFTs can absorb stellar radiation and contribute to the IR-variability of young stellar objects.
文摘The problem of determining the masses and ages of T Tauri star （TTS） using their evolu- tionary status is discussed. We test four pre-main sequence evolutionary models using well determined observational parameters of 12 binary TTSs and two binary red dwarfs. It is shown that the masses derived using the tracks of all models are in good agreement with flhe masses obtained from the obser- vations of TTSs with masses M 〉 0.7 Me （mean error ε,- 10%）. Low-mass stars with M ≤ 0.7 M⊙ have significantly greater mean error; e - 50% for the tracks of Bressan et al. and Chen et al., and e - 30% for the other tracks. The isochrones of all tested evolutionary models diverge for stars with masses M ≤ 0.7 M⊙. The difference increases with the mass decrease and can reach 10% of Kelvin- Helmholtz time for stars with mass M = 0.2 Me. The ages of most of the considered TTSs are smaller than the Kelvin-Helmholtz time. This confirms their evolutionary status of being pre-main sequence stars.
