An Isaac Newton Institute Workshop

Reconnection in the Sun and Magnetosphere (Hewlett-Packard and Spitalfields Days)

Some open problems for magnetic reconnection in solar flares

10th August 2004

Author: Bernhard Kliem (AIP, Potsdam, Germany)

Abstract

Following a brief overview of current flare models and the role of reconnection suggested for them, I will discuss a few open problems, which appear to be promising items for further research, in relation to the observations. These include the following questions.

(1) Does a termination shock in the downward reconnection outflow form?

(2) What is the nature of the hot, hazy structure that has been observed in a few flares above the post-flare loop arcade? What is the nature of the dark downflows typically observed in them?

(3) Can we explain the large numbers of individual hard X-ray spikes typically observed in the impulsive phase of flares by ``impulsive bursty'', i.e. resistive, reconnection?

(4) Does reconnection actually produce the waves supposed by models of stochastic particle acceleration (e.g. Miller et al. 1997, JGR 102, 14,631)?

(5) Does reconnection in a current sheet formed above erupting flux play an important role in the flare process? Which typical observational consequences do we expect?