Fast Line-Profile Variability in the Spectra of O Stars

A program of the search for and analysis of profile variability in the spectra of bright O supergiants with a time resolution of 5–30 min is described. Preliminary results of the spectroscopic observations of the stars λ Ori, α Cam, and 19 Cep with the 1-m Special Astrophysical Observatory telescope in 2001 are presented. Line-profile variability was detected in the spectra of all the stars studied; variability in the Hα and C III λ5696 A lines in the spectrum of λ Ori has been found for the first time. The variability amplitude is 4–5% for 19 Cep and 1–2% for α Cam and λ Ori on time scales from several hours to 3 or 4 days, and the width of the variable features reaches 2 A (100 km s−1). We detected cyclical variations in the He II λ4686 and C III λ5696 line profiles in the spectrum of λ Ori on time scales of 1.3–1.6 days. Rapid profile variations on time scales of 3.5–7 h were found in the violet parts of the Hα and He I λ4715 line profiles in the spectrum of λ Ori A.