Plasma ejections from a light bridge in a sunspot umbra

We present conspicuous activities of plasma ejections along a light bridge of a stable and mature sunspot in NOAA Active Region 8971 on 2000 May 2. We found the ejections both in the H alpha (10(4) K) images obtained with the Domeless Solar Telescope at Hida Observatory and in the 171 Angstrom (Fe I X/Fe X; similar to 10(6) K) images obtained with the Transition Region and Coronal Explorer. Main characteristics of the ejections are as follows: (1) Ejections occur intermittently and recurrently. (2) The velocities and the timings of the 171 Angstrom ejections are the same as those of H alpha eje ctions. (3) The appearance of the ejections are different from one another; i.e., the H alpha ejections have a jetlike appearance, while the 171 Angst rom ejections are like loops.