AAS 202nd Meeting, May 2003
Session 32 Stellar Atmospheres and Circumstellar Material
Poster, Tuesday, May 27, 2003, 10:00am-6:30pm, West Exhbit Hall

## [32.14] Winds from Non-Coronal'' and Hybrid'' Stars Driven by MHD Waves

V.S. Airapetian (The Catholic University of America/GSFC), K. Carpenter (NASA/GSFC), L. Ofman (The Catholic University of America/GSFC)

Observations obtained with IUE, HST and FUSE provide extensive data on atmospheric heating and wind dynamics for late-type luminous stars. The physical processes which drive winds in these stars are poorly understood, despite decades of study. In our previous study we have shown that observational signatures of winds can be interpreted by our model of winds driven by propagated Alfvén waves in stellar atmospheres and launched at a single frequency at the wind base (Airapetian et al. 2000). We extend our MHD calculations of winds from luminous late-type stars to include an Alfvén wave driver with a broad-band frequency range. The calculations are applied to non-coronal'' (\alpha Tau) and hybrid'' (\beta Dra) giant stars to consistently reproduce the observed velocity profiles of the winds, its terminal velocity, the turbulent broadening of UV lines and mass loss rates. The nature of wind variability in luminous late-type stars is discussed. We also present the preliminary results of our first MHD and LTE radiative transfer calculations to model the UV spectra from the K5 giant, {\alpha} Tau.

This research is supported by the NASA Research grant from GSFC No. NAG5-12869.