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.
Publication Source (Journal or Book title)
Benson, P., Clayton, G., Garnavich, P., & Szkody, P. (1994). Z Ursa Minoris - A new R coronae borealis variable. Astronomical Journal, 108 (1), 247-250. https://doi.org/10.1086/117063