Can the Solar Wind be Driven by Magnetic Reconnection in the Sun's Magnetic Carpet?

摘要

The physical processes that heat the solar corona and accelerate the solarwind remain unknown after many years of study. Some have suggested that thewind is driven by waves and turbulence in open magnetic flux tubes, and othershave suggested that plasma is injected into the open tubes by magneticreconnection with closed loops. In order to test the latter idea, we developedMonte Carlo simulations of the photospheric "magnetic carpet" and extrapolatedthe time-varying coronal field. These models were constructed for a range ofdifferent magnetic flux imbalance ratios. Completely balanced models representquiet regions on the Sun and source regions of slow solar wind streams. Highlyimbalanced models represent coronal holes and source regions of fast windstreams. The models agree with observed emergence rates, surface fluxdensities, and number distributions of magnetic elements. Despite having noimposed supergranular motions, a realistic network of magnetic "funnels"appeared spontaneously. We computed the rate at which closed field lines openup (i.e., recycling times for open flux), and we estimated the energy fluxreleased in reconnection events involving the opening up of closed flux tubes.For quiet regions and mixed-polarity coronal holes, these energy fluxes werefound to be much lower than required to accelerate the solar wind. For the mostimbalanced coronal holes, the energy fluxes may be large enough to power thesolar wind, but the recycling times are far longer than the time it takes thesolar wind to accelerate into the low corona. Thus, it is unlikely that eitherthe slow or fast solar wind is driven by reconnection and loop-openingprocesses in the magnetic carpet.