Emission-line profiles from Be-star envelopes with m=1 perturbation patterns

We have studied the variations in the Balmer-line profiles from Be-star disks with eccentric (i.e., m = 1) perturbation patterns. In order to examine the effects of oscillations on the line profiles, we assumed that the nonlinear perturbation patterns are similar to the linear m = 1 eigenfunctions. In addition, we assumed that the source function is constant over the entire disk. Based on these assumptions, we computed the optically-thick line profiles for various values of the disk parameters. We found that the line-profile variability due to the m = 1 perturbation patterns agrees well with the observed V/R variability. We also found that the amplitude of the profile shift associated with the V/R variation is sensitive to the density gradient in the radial direction. In particular, disks in which the local density decreases as steeply as r(-3) exhibit remarkable variabilities Like the observed V/R variations. These variabilities occur for a wide range of disk sizes and line optical depths.