We investigated three fan-shaped jets observed above sunspot light bridges or nearby sunspot regions. The study aimed to explore the dynamics and physical properties of jets’ features that appear as blob-like structures at the tips of the jets, which we call ‘dark blobs’. A transparent region is observed beneath the dark blobs, creating a visible gap between the dark blobs and the trailing body of the jets. These phenomena were studied in chromospheric and transition region imaging and spectral high-resolution co-observations from the Visible Imaging Spectrometer of the Goode Solar Telescope at the Big Bear Solar Observatory and the Interface Region Imaging Spectrograph (IRIS), together with data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. We analyzed the jets’ morphology and fine structure. We obtained the spatial scale and the dynamics of the dark blobs that are seen mostly in the wings of the Hα line and have a cross-section of about 0.2′′–0.3′′. The dark blobs and the transparent regions are seen bright (in emission) in the IRIS slit-jaw 1330 Å, 1400 Å, and AIA 304 Å images. The IRIS Si iv 1394 Å spectrum of the brightenings showed blue-shifted emission of about 16 km s−1 with non-thermal velocities of up to 40 km s−1. We also estimated the electron density of the blue-shifted brightenings to be 1012.1±0.2 cm−3. Our findings likely suggest that we detect the observational signatures of shock waves that generate and/or contribute to the evolution of fan-shaped jets.

Introduction
Observational Material
Results
    Jet on 2022 July 11 (JET1)
    Jet on 2015 September 3 (JET2)
    Jet on 2016 May 10 (JET3)
Discussion
Summary and Conclusions
Acknowledgments
References
Diagnosing the Electron Number Density of the UV/EUV Brightening at the Edge of the Jet.

• Heesu Yang(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea) Corresponding author
• Eun-Kyung Lim(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Maria S. Madjarska(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea, Max Planck Institute for Solar System Research, 37077 Göttingen, Germany, Space Research and Technology Institute, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria)
• Daniel Nóbrega-Siverio(Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain, Universidad de La Laguna, Dept. Astrofísica, E-38206 La Laguna, Tenerife, Spain, Rosseland Centre for Solar Physics, University of Oslo, 0315 Oslo, Norway, Institute of Theoretical Astrophysics, University of Oslo, 0315 Oslo, Norway)
• Klaus Galsgaard(School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews KY16 9SS, Scotland, UK)