The Born-again Planetary Nebulae Abell 30 and Abell 78
H. Todt, M. A. Guerrero, X. Fang, J. A. Toala, , J. S. Arthur, W. P. Blair, Y.-H. Chu, R. A. Gruendl, W.-R. Hamann, R. A. Marquez-Lugo, L. Oskinova, N. Ruiz, M. Steffen, D. Schönberner
The planetary nebulae Abell 30 and Abell 78 are born-again nebulae,
which are believed to have undergone a very late thermal pulse,
resulting in the ejection of hydrogen-poor material.
Born-again PNe are a rare phenomenon, only a few are known. It is really intriguing that in all cases the expansion of the hydrogen-poor ejecta is highly asymmetrical. Here we present new HST observations of the expansion of the ejecta in Abell 30 and Abell 78, and compare them to ≈20 yrs older HST images.