Can the Parker Solar Probe Detect a CME-flare Current Sheet?

Abstract

A current sheet (CS) is the central structure in the disrupting magnetic configuration during solar eruptions. More than 90% of the free magnetic energy (the difference between the energy in the nonpotential magnetic field and that in the potential one) stored in the coronal magnetic field beforehand is converted into the heating and kinetic energy of the plasma, as well as accelerating charged particles, by magnetic reconnection occurring in the CS. However, the detailed physical properties and fine structures of the CS are still unknown, since there is no relevant information obtained via in situ detections. The Parker Solar Probe (PSP) may provide us with such information should it traverse a CS in an eruption. The perihelion of PSP’s final orbit is located at about 10 solar radii from the center of the Sun, so it can observe the CS at a very close distance, or even traverse the CS, which would provide us with a unique opportunity to look into the fine properties and structures of the CS, helping to reveal the detailed physics of large-scale reconnection that would have been impossible before. We evaluate the probability that PSP can traverse a CS, and examine the orbit of a PSP-like spacecraft that has the highest probability to traverse a CS.

Flying through an Eruption-associated Magnetic Reconnection Current Sheet in the Solar Corona

“…The geometry of this CME, based on the forward model [6,38], suggests that a significant portion of it remains above the ecliptic, even though the source region is in the southern hemisphere. As a result, a considerable portion of the CME intersected the PSP trajectory, hinting towards a high probability of association of the current sheet with this CME [48]. Within the eruption current sheet, we observed an enhancement in both proton speed and plasma β, in contrast to typical properties of the HCS formed in the streamer belt, which is associated with high β but slow particle speeds [52].…”

“…We estimated the proxy of current density (j) [11], which features transient peaks at the locations of the steepest magnetic field gradient. Such locations mark the reversal of magnetic field, the width of which is ∼500 m. The width is larger than the upper limit (∼100 m) of the predicted proton Larmor radius [48], but, importantly, these measurements are limited by the temporal resolution of the FIELDS instrument.…”