Earth's Alfvén Wings Driven by the April 2023 Coronal Mass Ejection

• Published in: Geophysical research letters 2024-07, Vol.51 (14), p.n/a
• Main Authors: Chen, Li‐Jen, Gershman, Daniel, Burkholder, Brandon, Chen, Yuxi, Sarantos, Menelaos, Jian, Lan, Drake, James, Dong, Chuanfei, Gurram, Harsha, Shuster, Jason, Graham, Daniel B., Le Contel, Olivier, Schwartz, Steven J., Fuselier, Stephen, Madanian, Hadi, Pollock, Craig, Liang, Haoming, Argall, Matthew, Denton, Richard E., Rice, Rachel, Beedle, Jason, Genestreti, Kevin, Ardakani, Akhtar, Stanier, Adam, Le, Ari, Ng, Jonathan, Bessho, Naoki, Pandya, Megha, Wilder, Frederick, Gabrielse, Christine, Cohen, Ian, Wei, Hanying, Russell, Christopher T., Ergun, Robert, Torbert, Roy, Burch, James
• Format: Article
• Language: English
• Subjects: Alfv & eacute; Alfvén wings; CME-magnetosphere interaction; Cold shock; Corona; Coronal mass ejection; Earth; Earth ionosphere; Earth magnetosphere; Extrasolar planets; Filaments; Fluctuations; Highways; Ionosphere; Jupiter; Jupiter atmosphere; Jupiter satellites; magnetic cloud; Magnetic clouds; Magnetic field; Magnetic fields; Magnetic flux; Mercury; Mercury (planet); n wings; planetary magnetosphere; Planetary magnetospheres; Plasma; Saturn; Sciences of the Universe; Solar corona; Solar wind; Stellar coronas; Stellar magnetic fields; Stellar systems; Streaming; Sun; Sun-Earth connection; Wings
• ISSN: 0094-8276; 1944-8007; 1944-8007
• DOI: 10.1029/2024GL108894

We report a rare regime of Earth's magnetosphere interaction with sub‐Alfvénic solar wind in which the windsock‐like magnetosphere transforms into one with Alfvén wings. In the magnetic cloud of a Coronal Mass Ejection (CME) on 24 April 2023, NASA's Magnetospheric Multiscale mission distinguishes the following features: (a) unshocked and accelerated low‐beta CME plasma coming directly against Earth's dayside magnetosphere; (b) dynamical wing filaments representing new channels of magnetic connection between the magnetosphere and foot points of the Sun's erupted flux rope; (c) cold CME ions observed with energized counter‐streaming electrons, evidence of CME plasma captured due to by reconnection between magnetic‐cloud and Alfvén‐wing field lines. The reported measurements advance our knowledge of CME interaction with planetary magnetospheres, and open new opportunities to understand how sub‐Alfvénic plasma flows impact astrophysical bodies such as Mercury, moons of Jupiter, and exoplanets close to their host stars. Plain Language Summary Like supersonically fast fighter jets creating sonic shocks in the air, planet Earth typically moves in the magnetized solar wind at super‐Alfvénic speeds and generates a bow shock. Here we report unprecedented observations of Earth's magnetosphere interacting with a sub‐Alfvénic solar wind brought by an erupted magnetic flux rope from the Sun, called a coronal mass ejection (CME). The terrestrial bow shock disappears, leaving the magnetosphere exposed directly to the cold CME plasma and the strong magnetic field from the Sun's corona. Our results show that the magnetosphere transforms from its typical windsock‐like configuration to having wings that magnetically connect our planet to the Sun. The wings are highways for Earth's plasma to be lost to the Sun, and for the plasma from the foot points of the Sun's erupted flux rope to access Earth's ionosphere. Our work indicates highly dynamic generation and interaction of the wing filaments, shedding new light on how sub‐Alfvénic plasma wind may impact astrophysical bodies in our solar and other stellar systems. Key Points MMS observed a rare regime of magnetosphere interaction with unshocked low‐beta CME plasma Wing filaments represent dynamical channels of magnetic connection between the magnetosphere and foot points of the Sun's erupted flux rope Cold CME ions observed on closed field lines, likely generated by dual‐wing reconnection