The Variable Central Star of PN G243.8-37.1

Abstract

Spectroscopic and photometric variations of the central star of the planetary nebula PRTM 1 (PN G243.8-37.1) have been detected from optical spectrophotometric data. The photometric variations can be as large as ΔV~1 mag, but most of the time they are within 0.2 mag. The phenomenon seems to be cyclic. These optical changes confirm the UV variations reported by W. Feibelman from IUE archived data. The star presents a highly ionized spectrum, showing absorption lines of H I and He II. The stellar features also change, becoming deeper when the star is brighter, while at the same time the C IV λ5808 doublet appears in emission. The star cannot be classified as an ``O VI'' star, as proposed by W. Feibelman, because the optical O VI lines are absent from the spectrum. The nebular lines show no sign of variation. The possible origin of the stellar changes is discussed.