Journal Article

Martian Bow Shock Oscillations Driven by Solar Wind Variations: Simultaneous Observations From Tianwen‐1 and MAVEN

Su, Zhenpeng, Xiao, Sudong, Wu, Zhiyong, Hao, Xinjun, Chen, Manming, Mitchell, David L., Li, Yiren, Espley, Jared, Xu, Shaosui, Johnson, Catherine, Pan, Zonghao, Liu, Kai, Lillis, Robert, Halekas, Jasper S., Mittelholz, Anna, Wang, Guoqiang, Wang, Yuming, Zou, Zhuxuan, Chi, Yutian, Cheng, Long, Langlais, Benoit, Zhang, Tielong, Eparvier, Frank

2023

Overview

The Martian bow shock stands as the first defense against the solar wind and shapes the Martian magnetosphere. Previous studies showed the correlation between the Martian bow shock location and solar wind parameters. Here we present direct evidence of solar wind effects on the Martian bow shock by analyzing Tianwen‐1 and MAVEN data. We examined three cases where Tianwen‐1 data show rapid oscillations of the bow shock, while MAVEN data record changes in solar wind plasma and magnetic field. The results indicate that the bow shock is rapidly compressed and then expanded during the dynamic pressure pulse in the solar wind, and is also oscillated during the IMF rotation. The superposition of variations in multiple solar wind parameters leads to more intensive bow shock oscillation. This study emphasizes the importance of joint observations by Tianwen‐1 and MAVEN for studying the real‐time response of the Martian magnetosphere to the solar wind. Plain Language Summary The Martian bow shock is a standing shock wave that forms ahead of Mars due to the interaction with the solar wind, where the supersonic solar wind flow drops sharply to subsonic. The bow shock plays a crucial role in shaping the Martian magnetosphere and controlling the energy, mass, and momentum exchange between the solar wind and the Martian atmosphere. Previous research has shown that the position of Mars' bow shock is related to the solar wind. This research presents two‐spacecraft observations of how the solar wind affects the Martian bow shock. By analyzing data obtained by two orbiters, Tianwen‐1 and MAVEN, we find that the bow shock quickly contracts when the solar wind dynamic pressure rises or when the interplanetary magnetic field direction turns radial. When there are multiple changes in the solar wind at the same time, the bow shock moves around even more. This study shows how important it is to look at data from Tianwen‐1 and MAVEN at the same time to understand how Mars' magnetosphere reacts to the solar wind. Key Points First observations of the real‐time response of the Martian bow shock to changes in the upstream solar wind Direct evidence of the compression of the Martian bow shock under increased solar wind dynamic pressure Direct evidence of motion of the Martian bow shock caused by the rotation of the interplanetary magnetic field

• Publisher: John Wiley & Sons, Inc,American Geophysical Union,Wiley
• Subject: Charged particles / Contracts / Dynamic pressure / Interplanetary magnetic field / Magnetic field / Magnetic fields / Magnetospheric-solar wind relationships / Mars / Mars atmosphere / Momentum / Oscillations / Parameters / Planetary magnetospheres / Sciences of the Universe / Shock / Shock waves / Solar magnetic field / Solar oscillations / Solar wind / Solar wind effects / Solar wind flow / Solar wind parameters / Spacecraft / Time response / Wind effects / Wind flow / Wind variations