Letter to the Editor
The effects of high-frequency Alfvén waves on coronal heating and solar wind acceleration
Received 31 October 1996 / Accepted 28 November 1996
Wave effects in a two-fluid model for the solar corona and wind are studied. Heating and acceleration are achieved by high-frequency Alfvén waves, which are assumed to be created through small-scale reconnections in the chromospheric network. The wave energy flux is given in the model as a lower boundary condition. Waves with a power spectrum of the form in the frequency range from 1 to 800 Hz and with nT2 /Hz and Hz, corresponding to an integrated amplitude of 35 km/s, can heat the corona to a temperature of K at , and K (the maximum) at , starting from K at . Thermal and wave pressure gradients accelerate the wind to speeds of 100 km/s at , and 212 km/s at , starting from 2 km/s at in a rapidly diverging stream tube. Asymptotic wind speeds in the observed range of 700 to 800 km/s at 0.3 AU are obtained with wave amplitudes of 30 to 37 km/s in the frequency range from 1 to 30 Hz, corresponding to nT2 /Hz.
Key words: Sun: corona, solar wind
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© European Southern Observatory (ESO) 1997
Online publication: July 3, 1998