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Abell 70 is a planetary nebula (PN) whose nucleus at optical wavelengths is aG8 star with enhanced carbon and s-process abundances--a "barium star." Thecool star is a binary companion of the true, hot central star. In several othermembers of this rare class, the cool star is known to rotate with a period ofonly a few days. This is attributed to a spin-up that occurred due to accretionfrom the wind of the central star during its post-AGB PN ejection; this alsoaccounts for the unusual chemical composition of the companion's photosphere.We obtained photometry of the central star of Abell 70 on 104 nights in2010-11, and find a periodic 2.061-day variation, but with a variableamplitude--indicating that the variability is due to starspots on achromospherically active star. Abell 70 thus joins other members of this classin having a rapidly rotating and chemically peculiar late-type companion of thehot central star.

Periodic Variability of the Barium Central Star of the Planetary Nebula Abell 70