3 Ms in the life of beta Ceti: Sustained flare activity on a clump giant detected by the Extreme Ultraviolet Explorer

A 34 day Extreme Ultraviolet Explorer (EUVE) pointing on the "clump" giant beta Ceti (HD 4128; K0 III) recorded a series of striking coronal flare eve nts, reminiscent of a singular outburst seen previously from mu Velorum (HD 93497; G6 III + dF). The recent flaring episode contrasts with a more plac id behavior in a 6 day EUVE observation of beta Cet 6 years earlier. The av erage 70-180 Angstrom Deep Survey count rate in the new observation is twic e as high, and the 75-150 Angstrom spectrum displays a distinct hardening. The discovery of sustained flare activity on beta Cet raises the possibilit y that such episodes are more common than suspected among the core helium-b urning giants and sharpens the puzzle of the survival of magnetic activity beyond helium flash.