A Brightening of the Ultraviolet Spectrum of the Carbon Star HD 59643

The carbon star HD 59643 was observed at 66 A from 3840 to 7200 A in 1970 February. Long- ward of 4000 A the absorption spectrum matches previous descriptions, but weak hydrogen emission has now appeared. Below 4000 A the spectrum appears continuous, broken only by asymmetrical emiss'ion lines of hydrogen. There is no trace of the H- and K-lines of Ca ii which normally appear strongly in absorption when carbon stars are adequately exposed in the ultraviolet. The ultraviolet continuous emission must be of a transitory nature since it was not present when the star was observed by Wildt. Similar activity has been observed in the M star CH Cyg, but has not previously been reported in carbon stars.