S Persei--A Semi-regular Variable With Two Periods

Volume 3 number 1 (1974)

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Horace A. Smith

Abstract

The Variable star S Persei (021558) was discovered by A. Krueger in 1872 (Krueger, 1874) and it has been theobject of regular observation for more than ninety years, beginning in 1880. S Persei is listed in the 1969 GCVS as an SRc variable of spectral and luminosity types M3eIa-M4eIa, which is to say, a red supergiant with semi-regular variabiltiy. Figures 1(a) and 1(c) show the visual light curve of S Persei from 1880 until early 1974, after 1911 being based on AAVSO observations for the most part. Inspection of the light curve indicates that S Persei has distinctly cyclic light oscillations of greatly varying amplitude.