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arXiv · 2509.06792

3D structures of the base of small-scale recurrent jets revealed by Solar orbiter

Xiaohong Li·Sami K. Solanki·Thomas Wiegelmann·Gherardo Valori·Daniele Calchetti·Johann Hirzberger·Juan Sebastian Castellanos Duran·Joachim Woch·Achim Gandorfer·the Solar Orbiter team
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Abstract

Solar jets, characterized by small-scale plasma ejections along open magnetic field lines or the legs of large-scale coronal loops, play a crucial role in the dynamics of the solar atmosphere. Although spectral and EUV images have been widely used to analyze the formation and evolution of jets, the detailed 3D structure at the base of the jet has not been studied in detail due to the limitations in the spatial resolution of observations. Solar Orbiter enables us to investigate the structure of solar jets with much higher spatial and temporal resolutions and from a different angle than from Earth. By combining observations made by instruments onboard Solar Orbiter with data from the SDO, we analyzed recurrent solar jets originating in a mixed-polarity region near an active region. Additionally, we employed potential field and magnetohydrostatic extrapolation techniques to determine the magnetic field topology associated with the jets. The jets display dynamic, multi-strand outflows emanating from compact bright kernels above the magnetic inversion line, with apparent speeds exceeding 100 km/s. Magnetic field evolution reveals continuous flux cancellation at the jet footpoints. Throughout the sequence, base flows are confined within quasi-separatrix layers, with the highest velocities and temperatures located near coronal null points. Over four eruptions, the magnetic topology evolves from a simple fan-spine configuration with a single null to a more complex dome-shaped base containing multiple nulls with separatrix curtain, accompanied by a morphological transition from narrow, well-collimated spire to broader, fragmented outflows. These results provide the first direct observational evidence that dynamic changes in null-point geometry modulate jet morphology and energetics via successive reconnection episodes.

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Xiaohong Li, Sami K. Solanki, Thomas Wiegelmann, Gherardo Valori, Daniele Calchetti, Johann Hirzberger, Juan Sebastian Castellanos Duran, Joachim Woch, Achim Gandorfer, the Solar Orbiter team. 2025-09-08. 3D structures of the base of small-scale recurrent jets revealed by Solar orbiter. https://doi.org/10.1051/0004-6361%2F202555972

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