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Session 93 - Binary and Variable Stars.
Oral session, Friday, January 09
Lee (1997) carried out a photometric survey of light curve modulation among RR Lyrae stars. The goal was to determine the prevalence of the Blazhko effect and to investigate the various forms the effect takes. Of the 107 stars in the sample, V442 Her (period = 0.44 days) stood out for its extreme changes in light curve shape and amplitude over relatively long intervals of time. We have observed this star further and now have data from four observing seasons. The amplitude of the V light curve ranges from 0.29 mag to 1.40 mag. At large amplitude the light curve is a typical of a Bailey type ab RR Lyrae star while at small amplitude it does not resemble any type of RR Lyrae star. The best estimate of the period of the light curve modulation with the existing data is 885 days. Although this is not definitive given the temporal coverage now available, a shorter period appears unlikely from an examination of the data. We conclude that the modulation period of V442 Her is much longer than any other known RR Lyrae star. If the modulation of the light curve of this star is an example of the Blazhko effect, it represents a very extreme case. Whether this is so or whether the modulation is another phenomenon, this star deserves further study.
Program listing for Friday