X Per in 1996 - 1999: the Variability of Hydrogen and Helium lines

Abstract

We present the results of high-resolution (0.24Å/pix) monitoring of the variability of Hα and He I 6678 lines in the spectrum of X Per in 1996-99 at Tartu Observatory. The main characteristics of the line variability distinguishable in our data are:1) the intensity of emission peaks in both lines varies with a cycle-length ≈450 days, and displays a phase-lag between curves of two lines considered,2) in a cycle, both violet or red emission peaks emerge at high Doppler velocities but attain their maxima and disappear gradually at much lower velocities,3) despite of the considerable variability of equivalent width (EW) of both lines, the “relative emission measure” (EW(Hα)/EW(HeI)) behaves more constantly.