Using high-resolution observations from the New Vacuum Solar Telescope (NVST), PhD student WU Guotang and his advisor, Researcher YAN Xiaoli, from the Fuxian Lake Solar Observatory of Yunnan Observatories, Chinese Academy of Sciences, have detailed the physical characteristics of chromospheric jets in and around a sunspot. Their findings were published in The Astrophysical Journal.

The study focused on active region NOAA 13386, which was observed by the NVST on July 31, 2023. By analyzing high-resolution Hα data alongside extreme ultraviolet and magnetic field observations from the Solar Dynamics Observatory (SDO), the team performed a systematic analysis of the physical characteristics of chromospheric jets in and around the sunspot.

The results show that the inside jets have projected velocities of 4–14 km/s, lengths of 1–4 Mm, widths of 0.2–0.6 Mm, and lifetimes of 135–450 s; In contrast, the outside jets exhibit projected velocities of 8–50 km/s, lengths of 1–20 Mm, widths of 0.3–0.8 Mm, and lifetimes of 135–630 s, indicating that the outside jets have larger spatial and temporal scales than the inside jets.

Multiwavelength observations show that both types of jets exhibit clear brightenings in the corona, indicating high-temperature signatures. This suggests a potential contribution to chromospheric and coronal heating. Further analysis indicates that the inside jets are driven by partial magnetic reconnection between intersecting filaments, while line-of-sight magnetograms show that the outside jets are usually located in regions of opposite magnetic polarities and are closely associated with magnetic flux emergence.

This research provides new observational evidence for understanding the formation mechanisms of active-region jets and their roles in energy transport in the solar atmosphere. It also highlights the capability of high spatiotemporal resolution NVST data for investigating small-scale activities in the solar chromosphere.

This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Science Foundation of China, the Yunnan Key Laboratory of Solar Physics and Space Science, the Yunnan Fundamental Research Projects, the Yunnan Provincial Department of Education Science Research Fund Project, and the Chuxiong Normal University Doctoral Research Initiation Fund Project.

Figure 1. (a) Distribution of the sunspot and the jets analyzed in this study. The umbra is marked in black and the penumbra in white. The colors of the jets indicate the projected velocities. (b)–(e) Histograms comparing the velocity, length, width, and lifetime of the jets. Inside jets are shown in red, while outside jets are shown in blue. The dashed lines mark the mean values of each group. Image by WU.

Contact:
YAN Xiaoli
Yunnan Observatories, CAS
E-mail:yanxl@ynao.ac.cn