In addition to the primary, an A-type giant, there is a smaller and cooler companion in a 1.53 day orbit, probably an F-class star around absolute magnitude 3.0, and a more distant companion (star C or Ac) in an orbit calculated to be 702 days long. The close binary pair forms a rotating ellipsoidal variable with a 1.53 day period. Star C forms an Algol-type variable system with the close binary, showing both primary eclipses (when star C passes in front of the inner pair) and secondary eclipses (when the inner pair passes in front of star C). Timings of the eclipses show a 704.5-day period.
Light curves for b Persei. The top panel, plotted from TESS data, shows the variability of the inner binary pair. The lower panels, plotted from AAVSO data, show two eclipses.
12Samus, N. N.; Durlevich, O. V.; etal. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
123456789Hill, G.; Aikman, G. C. L.; Cowley, A. P.; Bolton, C. T.; Thomas, J. C. (1976). "The radio-flaring triple system B Per". The Astrophysical Journal. 208: 152. Bibcode:1976ApJ...208..152H. doi:10.1086/154590.
↑Koubský, Pavel; Hadrava, Petr; Šarounová, Lenka (December 2004). Study of b Per: an attempt to find lines of other components in the SB1 system. Spectroscopically and Spatially Resolving the Components of the Close Binary Stars. Vol.318. Astronomical Society of the Pacific. pp.103–106. Bibcode:2004ASPC..318..103K.
↑Collins, Donald F.; Sanborn, Jason; Zavala, Robert T. (May 2014). Modern V Photometry of the Eclipsing Triple System b Persei. The Society for Astronomical Sciences 33rd Annual Symposium on Telescope Science. Society for Astronomical Sciences. pp.205–211. Bibcode:2014SASS...33..205C.
12Duerbeck, H. W.; Schettler, A. (1979). "Photometric and spectroscopic study of the ellipsoidal variable b Persei". Acta Astronomica. 29: 225. Bibcode:1979AcA....29..225D.