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Published online by Cambridge University Press: 12 April 2016
IC 418 belongs to the group of about a dozen planetary nebulae with central stars that show irregular spectroscopic and photometric variations. Recent theoretical results provide arguments that this group may constitute a new class of pulsators. We present new photometric observations of the nucleus of IC 418 showing variations with a timescale of about 1/4 day. We discuss two possible explanations of the observed phenomena: pulsational instability and an unstable wind.