Initiation of solar flares: reconnection, heating, particle acceleration -Abstract

Proposer: Astrid Veronig, Institute of Physics, University of Graz, Austria

Abstract

Solar flares and coronal mass ejections (CMEs) are the most energetic phenomena in our solar system. The high radiation, fast particles and magnetic field brought by flare-CME events are the major sources of disturbances of our space weather at Earth. A fundamental process in magnetized plasmas, magnetic reconnection, is believed to drive these energetic events. However, how magnetic reconnection is initiated in flare-CME events, how and in which form the energy is originally released and distributed is still not sufficiently understood.

The pre-flare and early rise phases contain important information on the reconnection onset and the process initiating the energy release. With the launch of NASA's Solar Dynamics Observatory (SDO) in the year 2010, a powerful suite of instruments is continuously observing the Sun's magnetic field and its highly dynamic atmosphere with unprecedented spatial and temporal resolution over a broad temperature range from some 10³ to 10⁷ K. At the same time, NASA's Ramaty High Energy Solar Spectroscopic Imager (RHESSI) continues to provide high-quality X-ray imaging and spectroscopy to diagnose particle acceleration and plasma heating in solar flares.

Based on these unique data sources and on innovative methods to discriminate the thermal and nonthermal flare radiation, the proposed project addresses the following scientific questions, which are important for a better understanding of flare-CME events: (1) In which form is the flare energy originally released (plasma heating vs. particle acceleration)? (2) How and where does magnetic reconnection set in and how does it evolve? (3) How is the flare energy release related to the initiation and evolution of an associated CME eruption?