It is shown that a current sheet is formed in Parker's model of the solar corona from the requirement that magnetic helicity is conserved in the presence of a very small but finite plasma resistivity. The presence of dissipation permits slippage of field lines with respect to the plasma, and hence a current sheet can be formed in the presence of smooth photospheric flows. The structure of the current sheet encompasses a thin strip spanning two Y-points. It is shown that the rapid reconnection involved in the formation of the current sheet justifies the use of helicity conservation. Implications for coronal heating and numerical simulations of the corona are discussed.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Magnetic fields
- Sun: corona