CfA Colloquium: November 7, 2002

Speaker: Spiro Antiochos (NRL)

Title: The Magnetic Origins of Explosive Solar Activity

Abstract: The most spectacular and most energetic manifestations of solar activity are the giant disruptions of the Sun's magnetic field that give rise to coronal mass ejections (CME) and eruptive flares. Recent observations by the SOHO and TRACE missions of CME/eruptive flares and their associated prominence ejections have given us new insights into the physical mechanism for CME initiation. These phenomena are perhaps the most interesting of form solar activity from the viewpoint of basic MHD physics, and they present a great challenge to theory. The current theories and modeling of CMEs will be reviewed. In particular, we will describe a recently developed model, "magnetic breakout", which postulates that the interaction of neighboring flux systems via magnetic reconnection leads to the sudden release of magnetic stress stored in strong fields lying near the bottom of the solar atmosphere. Both 2.5D and 3D numerical simulations of breakout will be presented. The model proposes a general mechanism for explosive eruptions, which should be applicable to many astrophysical plasmas.

Reference for students:
Antiochos, S. K., DeVore, C. R., & Klimchuk 1999, ApJ, 510, 485.