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We critically discuss the recent observations of the binary system at thecenter of the bipolar planetary nebula Henize 2-428. We find that the proposedexplanation of two equal-mass degenerate objects with a total mass larger thanthe Chandrasekhar limiting mass that supposedly will merge in less than aHubble time, possibly leading to a SN~Ia, is controversial. This hypothesisrelies on the assumption that the variability of the He II 5412A spectral lineis due to two absorption components. Instead, we propose that it can beaccounted for by a broad absorption line from the central system on top ofwhich there is a narrow emission line from the nebula. This prompted us tostudy if the binary system can be made of a degenerate star and a low-mass mainsequence companion, or of two degenerate objects of smaller mass. We find thatalthough both scenarios can account for the existence of two symmetric broadminima in the light curve, the second one agrees better with observations. Wethus argue that the claim that Henize 2-428 provides observational evidencesupporting the double-degenerate scenario for SN~Ia is premature.

Is the central binary system of the planetary nebula Henize 2-428 a Type Ia supernova progenitor?