Periodicities in the Ultraviolet Flux of α Orionis

Abstract

We have used low-resolution spectra from the International Ultraviolet Explorer (IUE) to look for periodicities in the ultraviolet flux from α Orionis. The total continuum flux for each observation was integrated, producing longwave (1900-3200 Å) and shortwave (1250-1750 Å) light curves. The periodograms resulting from the shortwave data are noiselike, but the longwave light curves yield statistically significant periods of T₁=3.46 yr and T₂=0.531 yr. From the shortwave data, we found no statistically significant periods. Both periods are further supported by harmonic fits and data folding. We discuss the possible implications of these periodic fluctuations, specifically in regards to pulsation, convection, and binarity.