Turbulent Origins of Solar and Stellar Winds
Steven Cranmer (University of Colorado Boulder)
May 07, 2015
Abstract: All stars are believed to possess expanding outer atmospheres known as stellar winds. The continual evaporation of gas from stars has a significant impact on stellar and planetary evolution, and also on the larger-scale evolution of gas and dust in galaxies. Despite more than a half-century of study, though, the basic mechanisms responsible for producing many kinds of stellar winds are still unknown. Fortunately, there has been a great deal of recent progress toward identifying and characterizing the processes that produce our own Sun’s hot corona and fast wind. Based on this progress, we have developed a new generation of theoretical models of stellar wind acceleration for cool main- sequence stars and evolved giants. These models follow the production of magnetohydrodynamic turbulent motions from subsurface convection zones to their eventual dissipation and escape through the stellar wind. This talk will also briefly discuss other types of stars (mainly more massive than the Sun) with winds driven by their intense radiation fields. Although these stars do not appear to exhibit solar-like coronal heating, the study of heliospheric waves and turbulence nevertheless has been useful to apply to their fluctuating winds.