Observation of Interchange Reconnection on Mars

Abstract

Without a global dipole magnetic field, Mars has magnetic anomalies, i.e., crustal fields, in the southern hemisphere and interesting flexible magnetic fields in the magnetotail. The magnetic field topology is complex and flexible in the Martian magnetotail, especially over regions of strong crustal fields. However, the answer to how the magnetic field topology within crustal field regions transitions is elusive. Here we report the first case of interchange reconnection between open and closed crustal fields in the near-Mars magnetotail, using Mars Atmosphere and Volatile Evolution (MAVEN) observations. While MAVEN crossed from a region of closed crustal field to one of open crustal field, several characteristics of reconnection, such as the Hall magnetic field and plasma outflow, were observed. And plasmas are exchanged in the reconnection region. Our observations demonstrate that interchange reconnection can occur between open and closed crustal fields in the Martian near-magnetotail. Interchange reconnection occurring on the nightside changes the magnetic field topology within the crustal field regions and contributes to the escape of heavy ions.

Direct Observations of Magnetic Reconnections at the Magnetopause of the Martian Mini‐Magnetosphere

“…On the night side of Mars, the magnetic field topology can switch frequently, which probably occurs due to reconnection between the crustal field and the draped field (Harada et al, 2018;Weber et al, 2020) or the crustal field itself (Chen et al, 2023;Lin et al, 2024). This process may similarly occur above the crustal field on the dayside, where magnetic reconnection can occur and change the local magnetic field topology when the IMF direction is opposite to the crustal field direction, as shown in the present study.…”

“…Cravens et al (2020) evaluated the role of magnetic reconnection in the dayside ionosphere of Mars in the collisional regime. Magnetic reconnection across crustal field regions in the Martian magnetotail has been reported (Chen et al, 2023;Lin et al, 2024). Recently, a magnetohydrodynamic simulation showed dayside magnetic reconnection between the solar wind and the Martian crustal field (M. Wang et al, 2022).…”

Guide Field Dependence of Energy Conversion and Magnetic Topologies in Reconnection Turbulent Outflow

“…The diffusion region, comprising the ion diffusion region (IDR) and electron diffusion region (EDR), plays a pivotal role in governing the energy conversion process (e.g., Hesse et al, 1999;Mozer et al, 2003;Pritchett & Mozer, 2009;Xiong et al, 2022aXiong et al, , 2022b. Within these regions, particles undergo acceleration and heating, contributing to the formation of high-speed jets in the outflow region (e.g., Huang, Zhou, et al, 2015;Lin et al, 2024;Torbert et al, 2018;Xiong et al, 2022cXiong et al, , 2023b. Moreover, it is suggested that these outflow jets can extend further downstream than theoretically predicted (e.g., Huang et al, 2021;Phan et al, 2007;Zhong et al, 2020), inducing turbulence within the outflow (e.g., Leonardis et al, 2013;Fu et al, 2017).…”