Authors: Bin Zhuang (University of New Hampshire), Noé Lugaz (University of New Hampshire), Charles J. Farrugia (University of New Hampshire), Xiaocan Li (Los Alamos National Laboratory), Tingyu Gou (Harvard-Smithsonian Center for Astrophysics), Nada Al-Haddad (University of New Hampshire), and Sahanaj A. Banu (University of New Hampshire)

The coherence of coronal mass ejections (CMEs) is an important topic for understanding the evolution of CME flux rope structures and for improving space weather forecasting. Previous studies have shown that magnetic reconnection is one of the main reasons that cause CME incoherence. This reconnection usually happens near the front or rear boundary of the CME, or is caused by the interaction between CMEs and other large-scale solar wind structures. However, for isolated CMEs, large-scale current sheets can also form near the center of the CME. The internal magnetic reconnection caused by such current sheets can greatly change the structure and properties of the flux rope. We investigate the 2023 April 23 CME, which was observed in situ by several near-Earth spacecraft including Wind, ACE, DSCOVR, and ARTEMIS, as well as by STEREO-A, which was located about 10 degrees east of Earth at that time. Using remote sensing observations from heliospheric imagers on STEREO-A and Solar Orbiter, we confirm that both near-Earth spacecraft and STEREO-A observed the same isolated CME. However, the in-situ magnetic field measurements show clear differences between the two groups of spacecraft. We find that these differences are closely related to a large-scale current sheet that is detected near the center of the CME, but only by the near-Earth spacecraft. This current sheet moves together with the CME and drives internal magnetic reconnection inside the flux rope. We discuss how this current sheet is formed inside the CME, and how the internal reconnection, combined with the different spacecraft trajectories, leads to the different flux rope measurements observed at the two locations.