http://arxiv.org/abs/1808.01251
Abell 70 is a planetary nebula (PN) whose nucleus at optical wavelengths is a G8 star with enhanced carbon and s-process abundances–a “barium star.” The cool star is a binary companion of the true, hot central star. In several other members of this rare class, the cool star is known to rotate with a period of only a few days. This is attributed to a spin-up that occurred due to accretion from the wind of the central star during its post-AGB PN ejection; this also accounts for the unusual chemical composition of the companion’s photosphere. We obtained photometry of the central star of Abell 70 on 104 nights in 2010-11, and find a periodic 2.061-day variation, but with a variable amplitude–indicating that the variability is due to starspots on a chromospherically active star. Abell 70 thus joins other members of this class in having a rapidly rotating and chemically peculiar late-type companion of the hot central star.
H. Bond and R. Ciardullo
Mon, 6 Aug 18
28/33
Comments: Accepted by Research Notes of the AAS. Published version will be slightly shorter due to word-count limitations
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