Plasma-neutral gas simulations of reconnection events in cometary tails

Abstract

Abstract. The formation and dynamical evolution of cometary plasma tails and magnetic boundary layers is studied by the first numerical plasma-neutral gas simulations. It is shown that collisional interaction between the cometary neutral envelope and the solar wind plasma leads to the formation of a magnetic barrier that separates the entire cometary body from the solar wind. The overall dynamics, in particular, of the magnetotail are governed by magnetic reconnection. Multiple reconnection events are initiated by the localized excitation of anomalous resistivity modeled by η( j). If the comet encounters a heliospheric current sheet, strong disconnection events characterize the cometary plasma tail. But even in the case of homogeneous solar wind conditions, partial disruption of the tail is triggered by dayside reconnection.

A global model of cometary tail disconnection events triggered by solar wind magnetic variations

“…In Figure 3c, the configuration of magnetic filed lines is gradually evolving to a stage consistent with the resistive MHD results of [ Konz et al , 2004], in which tail magnetic reconnection during such DEs is examined. Compared with the two‐dimensional Konz et al result, which focuses more on the microphysical details, our ideal MHD model is using a reconnection process created by numerical diffusion to study the overall dynamic process.…”

“…It is this coincidence that helps the magnetic reconnection to effectively move a large amount of plasma into the tail. Frontside reconnections during a DE are also discussed in previous MHD results with less grid resolution, where the corresponding resistivity and magnetic diffusion are presented [ Yi et al , 1996; Konz et al , 2004]. At this moment in Figure 3a, the HCS has not yet propagated to the tail, so the thin high density sheet in the tail still represents the steady state tail density distribution.…”

“…Both models have found constant tail reconnection during steady solar wind condition. Konz et al [2004] have examined time evolution of current density and field strength using their plasma‐neutral gas model. The morphology as well as the dayside magnetic diffusion and nightside magnetic reconnection is discussed thereafter.…”

“…An extensive study about the magnetic reconnections during such DEs has been carried out by two‐dimensional simulations of Ogino et al [1986] and Konz et al [2004]. Both models have found constant tail reconnection during steady solar wind condition.…”

The interaction of comet 153P/Ikeya‐Zhang with interplanetary coronal mass ejections: Identification of fast ICME signatures

“…Disconnection events (DEs) are large‐scale removals of essentially entire ion tails. These occur at heliospheric current sheet (HCS) crossings [ Niedner and Brandt , 1978; Yi et al , 1996; Brandt et al , 1999; Konz et al , 2004].…”