Small-scale explosive events or microflares occur throughout the
chromospheric network of the Sun. They are seen as sudden bursts of highly
Doppler shifted spectral lines of ions formed at temperatures in the range
2x10^4 - 5x10^5 K. They tend to occur near regions of cancelling photospheric
magnetic fields and are thought to be directly associated with magnetic field
reconnection. Recent observations have revealed that they have a bi-directional
jet structure reminiscent of Petschek reconnection. In this paper compressible
MHD simulations of the evolution of a current sheet to a steady Petschek,
jet-like configuration are computed using the Versatile Advection Code. We
obtain velocity profiles that can be compared with recent ultraviolet line
profile observations. By choosing initial conditions representative of magnetic
loops in the solar corona and chromosphere, it is possible to explain the fact
that jets flowing outward into the corona are more extended and appear before
jets flowing towards the chromosphere. This model can reproduce the high
Doppler shifted components of the line profiles but the brightening at low
velocities, near the centre of the bi-directional jet, cannot be explained by
this simple MHD model.Comment: 16 pages, 8 figures. To be published in Solar Physic
