Some observational appearances of m=1 density waves in Be star disks

Abstract

One-armed (i.e., m = 1) density waves are the only global waves in nearly Keplerian disks (Kato 1983). Their frequencies are much smaller than the angular frequency of disk rotation. Based on this theory, Okazaki (1991) proposed that the long-term V/R variations of Be stars are phenomena caused by the global m = 1 oscillations in the equatorial disks. Hummel and Hanuschik (1993) showed that line profiles of disks with m = 1 perturbation patterns are in agreement with the observed V/R variability.