Penumbral Microjets in Sunspot Chromospheres: Evidence of Magnetic Reconnection

  • Yukio Katsukawa
Part of the Astrophysics and Space Science Library book series (ASSL, volume 449)


It is not too much to say that the greatest achievement of the Hinode Solar Optical Telescope is observational demonstration of active plasma ejections (i.e., jets) occurring everywhere in the solar chromosphere. Among them, the penumbral microjets newly discovered by Hinode are a small-scale jet phenomenon that occurs frequently in the chromosphere above a sunspot penumbra. They are important because we can show strong evidence supporting magnetic reconnection as a driver of chromospheric jets because we can observe in detail the magnetic field and velocity structures around the site where a penumbral microjet occurs. The observation of penumbral microjets gave rise to strong recognition of the importance of magnetic reconnection in driving transient energy release even when the magnetic fields are not completely antiparallel. Recent progress in high-resolution observations of transition regions and coronae suggests the possible influence of penumbral microjets in the atmosphere outer than the chromosphere.


Sun Hinode Sun: chromosphere Jets Sunspots 



I’d like to thank all the people who contributed to the development and operation of the Hinode SOT in Japan for 10 years, especially Drs. S. Tsuneta, T. Shimizu, Y. Suematsu, K. Ichimoto, T. J. Okamoto, and M. Kubo, and Mr. T. Bando. Members of the US-SOT team, especially Drs. T. Tarbell and R. Shine, are also acknowledged for their close cooperation. I’d also like to thank Drs. J. Jurcak and K. Reardon for their close cooperation in the studies of penumbral microjets.


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© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Solar Science ObservatoryNational Astronomical Observatory of JapanMitaka, TokyoJapan

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