3996 20190130134523.0 CTALK-2019-0063 van Hoof, P. A. M. Observations of born-again stars 2018 2018-09-13 Born-again stars are central stars of planetary nebulae (PNCS) that have undergone a (very) late thermal pulse after they have left the AGB. Evolutionary models predict that around 10-20% of PNCS should undergo a (V)LTP, yet only a handful of born-again objects are known. Only two of these were seen undergoing the flash: V605 Aql in 1918 and V4334 Sgr (a.k.a. Sakurai's object) in 1996. In my review I will give an overview of the observations of these objects, focusing mainly on V4334 Sgr as this is by far the best observed example of a born-again star. The talk will cover both observations of the central star and the circumstellar material that was ejected in the (V)LTP event. NO Kimeswenger, S. Van de Steene, G. C. Avison, A. Zijlstra, A. A. Guzman Ramirez, L. Herwig, F. Hajduk, M. Hydrogen Deficient Stars 2018, Armagh, UK peter.vanhoof@observatoire.be 2555693 http://publi2-as.oma.be/record/3996/files/vanHoof.pdf 11964 http://publi2-as.oma.be/record/3996/files/vanHoof.gif?subformat=icon icon 7714 http://publi2-as.oma.be/record/3996/files/vanHoof.jpg?subformat=icon-180 icon-180 Invited CTALKINVI