THEORETICAL-MODELS FOR THE SOLAR-WIND

Theoretical models for the solar wind are reviewed from the point of view that a hot corona cannot be simply assumed as a given inner boundary but rather as part of the overall problem and needs to be explained in the first place. Models including the transition region and the heating of the corona and the coronal radiative and conductive losses are discussed. The input at the sun of small-scale mechanical energy and of waves and turbulence in the wind are addressed, as well as interplanetary constraints placed on the coronal and wind expansion by in situ measurements. Recent theoretical attempts to explain the relative constancy of the observed mass flux in the framework of multifluid models including Coulomb collisions are presented. Whether or not the coronal temperature inversion can be modeled by exospheric kinetic models, a currently debated issue, is briefly dealt with. More exotic concepts of solar wind acceleration by means of plasmoids are also discussed.