Binary [WR] and wels central stars of planetary nebulae

A sample of 33 [WR] and wels (weak emission‐line central stars) central stars of planetary nebulae was observed in order to search for binary nuclei. One close binary system was discovered. The central star of PN G 222.8 − 04.2 is the first [WR] star in a close binary system known, with a period of 0.63 d . The fraction of close binary central stars, leading to photometrical variability, is lower among the hydrogen‐poor [WR] stars and wels than among their hydrogen‐rich counterparts. This may indicate larger orbital separations or an intrinsically lower binary fraction among [WR] and wels central stars. The detection of one close binary system among the [WR] stars shows that common‐envelope evolution does not preclude such stars. It also shows that although a stellar merger is a possible evolutionary channel towards H‐poor emission‐line stars, it cannot form the only such channel, as PN G 222.8 − 04.2 has avoided a merger.