Transient Mass-Loss Events in the PG 1159 Central Star of Longmore 4

A spectacular, transient mass-loss event in the hydrogen-deficient central star of the planetary nebula Longmore 4 was discovered in 1992 by Werner et al. During that event, the star temporarily changed from its normal PG 1159 spectrum to that of an emission-line [WCE] star. I have been monitoring the spectrum of Lo 4 since 2003. Out of 31 spectra, two of them reveal mass-loss outbursts similar to the one seen in 1992, showing that the phenomenon recurs. I speculate on possible mechanisms for these unique outbursts, but emphasize that we still have no fully convincing explanation.