Large-scale Structure of the Heliospheric Current Sheets within the Heliosheath Inferred from Voyager 2 Observations

• Published in: The Astrophysical journal Vol. 974; no. 2; pp. 152 - 164
• Main Authors: Choi, Dooyoung, Lee, Dae-Young, Choi, Kyung-Eun, Noh, Sung Jun, Kim, Kyung-Chan
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.10.2024; IOP Publishing
• Subjects: Current sheets; Equator; Heliosheath; Heliosphere; Latitude; Magnetic reconnection; Solar maximum; Spacecraft; Thickness
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad6e82

Abstract In this paper, we conducted an analysis of the heliospheric current sheets (HCSs) in the heliosheath (HS), utilizing observations by Voyager 2 between 2008 and 2018. Employing rigorous criteria, we identified a total of 34 HCSs that indicate significant changes in magnetic polarity. These occurrences were more prevalent during solar maximum periods when the HCS expanded to higher latitudes, coinciding with the spacecraft positioned at an average latitude of −31° from the solar equator. We determined certain features of the large-scale structures of the identified HCSs. Most importantly, employing two distinct methods indicates that the thickness of the HCSs within the HS ranges from ∼0.003 to ∼0.4 au with an average thickness of ∼0.03 to ∼0.1 au, depending on methods of event selection and fitting techniques. This thickness surpasses that known near 1 au or other heliospheric distances. It is also notably thicker than the typical proton inertial length, implying unfavorable conditions for magnetic reconnection. Additionally, our analysis reveals a frequent tilt of HCS planes relative to the solar equatorial plane by a varying angle up to several tens of degrees, likely implying a common occurrence of a warped structure of the HCS within the HS. Longitudinally, the HCS planes closely align with the Parker spiral field direction expected in the HS. Finally, for a large fraction of the identified HCS events, the HCS planes are likely characterized by a rotational discontinuity. These findings are valid within the limits of the 1 hr resolution data used in this study.