Goddard Space Flight Center
The Dynamic Connection Between the Sun and Heliosphere
Since the pioneering theoretical work of Parker in 1958, later confirmed by satellite observations in the heliosphere, it has been known that the Sun's atmosphere streams continuously outward in the form of a supersonic wind. At a basic level the origin of the wind is straightforward: the difference in gas pressure between the Sun's million-degree corona and the tenuous interstellar plasma causes the corona to expand outward. The Sun's intense magnetic field, however, adds both structure and dynamics to this simple picture. The field divides the corona into regions that are "open" (i.e., connect to the heliosphere and "closed" (confined to the Sun). Furthermore, the field structures the heliosphere into quasi-steady "fast" wind and fully dynamic "slow" wind. The fast wind has been clearly observed to originate in open coronal regions, but the source of the slow wind has long been one of the major problems in solar/heliospheric physics. I will present an overview of our present state of knowledge of the corona and wind, and then discuss a new theory, the S-Web model, that may explain the slow wind.