Solitary Magnetic Structures Developed From Gyro‐Resonance With Solar Wind Ions at Mars and Earth. Issue 3 (4th February 2022)

• Record Type: Journal Article
• Authors: Chen, Li‐Jen; Halekas, Jasper; Wang, Shan; DiBraccio, Gina A.; Romanelli, Norberto; Ng, Jonathan; Russell, Christopher T.; Schwartz, Steven J.; Sibeck, David G.; Farrell, William; Pollock, Craig; Gershman, Daniel; Giles, Barbara; Collado‐Vega, Yaireska M.
• Is Part Of: Geophysical research letters. Volume 49:Issue 3(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-04
• Subjects: instabilities -- foreshock -- nonlinear waves -- planetary magnetosphere -- space weather -- Mars ion escape; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL097600
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We investigate solitary magnetic structures in the foreshock of Mars and Earth. The structures exhibit pulse‐like magnetic field and density enhancements along with plasma heating and local solar wind (SW) ion reflection. The structures at Mars resemble the foreshock structures developed from ultra‐low‐frequency electromagnetic waves gyro‐resonant with SW ions at Earth, and propagate toward the magnetosphere. We perform fully kinetic simulations to reproduce the solitary structures and the nonlinear evolution of ion distribution functions, illustrating their resonance with SW ions. The structures present self‐induced foreshock turbulence that can have space weather effects. Our results advance the fundamental understanding of how SW interacts with planetary magnetospheres, and have potential impact on the current picture of planet‐origin ion escape. Plain Language Summary: The permanent magnetic field at Mars, even though much weaker than that of the Earth, works together with the ionosphere to stand off the solar wind and produce a bow shock. We study planet‐sized magnetic field pulses locally generated and amplified in the region just upstream of the shocked solar wind (SW). These pulses locally heat the plasma and reflect the incoming SW, behaving like mini‐shocks moving toward the planets. We discuss how the pulses are generated and their potential to lead to dayside escape of planetary ions. Key Points: Solitary magnetic structures with density enhancements, plasma heating, and ion reflection are observed in the Martian foreshock The structures resemble those developed from foreshock waves gyro‐resonant with solar wind ions at Earth The structures and ion distributions are reproduced by simulations, and shown to be self‐induced turbulence