MHD waves from inhomogeneous accretion in T Tauri stellar magnetospheres
Abstract
The authors consider the radiation of MHD-waves when a protostellar plasma cloud falls along an ambient magnetic field onto the surface of a T Tauri star. It is shown that the excitation mechanism is efficient in the frequency interval 0 < ω ⪉ 4 vc/rc where the infall velocity vc of the cloud is taken to be subalfvénic and rc is the radius of the cloud. The efficiency of wave-excitation is calculated and turns out to be of order 0.1 (ρc/ρ0)(vc/cA)3 for the Alfvén mode and of order 1.8 (ρc/ρ0)(vc/cA)7 for the fast mode (cA is the Alfvén speed, ρc is the mass density inside the cloud and ρ0 that of the ambient atmosphere).
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1988
- Bibcode:
- 1988A&A...190..178S
- Keywords:
-
- Magnetohydrodynamic Waves;
- Pre-Main Sequence Stars;
- Stellar Magnetic Fields;
- Stellar Magnetospheres;
- Stellar Mass Accretion;
- T Tauri Stars;
- Astrophysics