Does reconnection only occur at points of maximum shear on Mercury's dayside magnetopause?
Does reconnection only occur at points of maximum shear on Mercury's dayside magnetopause?
MESSENGER observations of large numbers of flux transfer events (FTEs) during dayside crossings of Mercury's magnetopause have shown that the highly dynamic Hermean magnetosphere is strongly driven by frequent and intense magnetic reconnection. Since FTEs are products of reconnection, study of them can reveal information about whether reconnection sites favor points of maximum shear on the magnetopause. Here, we analyze 201 FTEs formed under relatively stable upstream solar wind conditions as observed by MESSENGER during inbound magnetopause crossings. By modeling paths of these FTEs along the magnetopause, we determine the conditions and locations of the reconnection sites at which these FTEs were likely formed. The majority of these FTE formation paths were found to intersect with high-magnetic shear regions, defined as shear angles above 135°. Seven FTEs were found where the maximum shear angle possible between the reconnecting magnetic field lines was less than 80° and three of these had shear angles less than 70°, supporting the idea that very low-shear reconnection could be occurring on Mercury's dayside magnetopause under this global-scale picture of magnetic reconnection. Additionally, for the FTEs formed under these low-shear reconnection conditions, tracing a dominant X-line connecting points of maximum shear along the magnetopause that passes through a region of very low-shear may be difficult to justify, implying reconnection could be occurring anywhere along Mercury's magnetopause and may not be confined to points of maximum shear.
Mercury, flux transfer events, magnetic shear angle, magnetopause, reconnection
Zomerdijk‐russell, S.
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Masters, A.
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Sun, W. J.
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Fear, R. C.
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Slavin, J. A.
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1 November 2023
Zomerdijk‐russell, S.
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Masters, A.
4cea46b1-d34e-4e7a-b00a-ea1bb182250e
Sun, W. J.
2c350b8d-15d6-4eb3-b329-37da74267451
Fear, R. C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Slavin, J. A.
18c6ffa4-123f-47db-a157-2d8865090bbd
Zomerdijk‐russell, S., Masters, A., Sun, W. J., Fear, R. C. and Slavin, J. A.
(2023)
Does reconnection only occur at points of maximum shear on Mercury's dayside magnetopause?
Journal of Geophysical Research: Space Physics, 128 (11), [e2023JA031810].
(doi:10.1029/2023JA031810).
Abstract
MESSENGER observations of large numbers of flux transfer events (FTEs) during dayside crossings of Mercury's magnetopause have shown that the highly dynamic Hermean magnetosphere is strongly driven by frequent and intense magnetic reconnection. Since FTEs are products of reconnection, study of them can reveal information about whether reconnection sites favor points of maximum shear on the magnetopause. Here, we analyze 201 FTEs formed under relatively stable upstream solar wind conditions as observed by MESSENGER during inbound magnetopause crossings. By modeling paths of these FTEs along the magnetopause, we determine the conditions and locations of the reconnection sites at which these FTEs were likely formed. The majority of these FTE formation paths were found to intersect with high-magnetic shear regions, defined as shear angles above 135°. Seven FTEs were found where the maximum shear angle possible between the reconnecting magnetic field lines was less than 80° and three of these had shear angles less than 70°, supporting the idea that very low-shear reconnection could be occurring on Mercury's dayside magnetopause under this global-scale picture of magnetic reconnection. Additionally, for the FTEs formed under these low-shear reconnection conditions, tracing a dominant X-line connecting points of maximum shear along the magnetopause that passes through a region of very low-shear may be difficult to justify, implying reconnection could be occurring anywhere along Mercury's magnetopause and may not be confined to points of maximum shear.
Text
JGR Space Physics - 2023 - Zomerdijk‐Russell - Does Reconnection Only Occur at Points of Maximum Shear on Mercury s Dayside
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Accepted/In Press date: 7 October 2023
e-pub ahead of print date: 26 October 2023
Published date: 1 November 2023
Additional Information:
Funding Information:
S.Z.‐R. is supported by an STFC Studentship 2439770. A.M. is supported by a Royal Society University Research Fellowship. R.C.F is supported by an STFC Consolidated Grant ST/V000942/1. W.S. and J.A.S. are supported by NASA Grant 80NSSC21K0052 and Discovery Data Analysis Program Grant 80NSSC22K1061.
Publisher Copyright:
©2023. The Authors.
Keywords:
Mercury, flux transfer events, magnetic shear angle, magnetopause, reconnection
Identifiers
Local EPrints ID: 484568
URI: http://eprints.soton.ac.uk/id/eprint/484568
ISSN: 2169-9380
PURE UUID: 4434e611-6b1d-4288-8ce8-db47adef82e8
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Date deposited: 16 Nov 2023 18:06
Last modified: 18 Mar 2024 03:28
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Contributors
Author:
S. Zomerdijk‐russell
Author:
A. Masters
Author:
W. J. Sun
Author:
J. A. Slavin
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