Z Ursa Minoris-A New R Coronae Borealis Variable

We have monitored Z Ursa Minoris using a V filter beginning 1992 April. It suddenly dimmed by almost 6 mag in late summer 1993. We obtained a spectrum 1993 November 20.54 UT which confirms that Z UMi is probably an R Coronae Borealis (RCB) star. The spectrum of Z UMi shows the strong carbon bands and weak hydrogen lines of an RCB star. It also shows the typical late decline emission in the Na I D lines. The light curve shows evidence for stellar pulsations as well as the large and rapid fading which characterizes the RCB stars.