The subject of this thesis is the time-series analysis of 130 échelle spectra of ε Ori obtained at Ritter Observatory on the campus of the University of Toledo. These data were acquired over seven observing seasons between 1998 and 2006. The spectra include the Hα line, which is formed mainly in the inner wind region, and the He I λ5876 triplet, which is mostly a photospheric absorption line with weak wind features present in the wings. The equivalent widths of Hα (net) and the He I were measured and radial velocity measurements were obtained from the central absorption of the He I line.
Temporal variance spectra were computed in order to quantify the variability and revealed significant wind variability in both Hα and He I. The He I TVS had a double-peaked profile consistent with radial velocity oscillations due to pulsations. Periodicity searches were carried out on the equivalent width, radial velocity and wavelength-binned spectral time series. A method developed by Bretthorst (2001) which applies Bayesian inference to the Lomb-Scargle (Lomb, 1976; Scargle, 1982) periodogram has been used in the period search on all data. The CLEAN algorithm (Roberts, Lehar, and Dreher, 1987) was also applied to the equivalent width time series. The Bayesian technique was used to construct 2D periodograms from the wavelength-binned spectra.
This research has uncovered several apparently real periods. Signals with time scales on the order of the rotational period, which may be due to rotationally modulated structure, were detected in data from two seasons. Many periods with time scales of 2-8 d are present in the data. A photospheric origin is suspected for periods present in He I and radial velocity data but a wind origin cannot be ruled out. The periods detected in the Hα data are likely due to wind variability. A period of 4.4 d, was detected in nearly every season. This period was found in both Hα and He I and may indicate a persistent or recurring phenomenon. A 2.2 d period was detected in the radial velocity data that may be the overtone of the 4.4 d period. The periods have times scales consistent with non-radial pulsations. Pulsations may be inducing harmonic modulation of the wind.