Emission-Line Profiles from Be-Star Envelopes with m=1 Perturbation Patterns

Atsuo T. OKAZAKI
College of General Education, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062, Japan
Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Kruislaan 403,
1098 SJ Amsterdam, The Netherlands

(Received 1991 January 30; accepted 1996 January 25)

Abstract:

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 exhibit remarkable variabilities like the observed V/R variations. These variabilities occur for a wide range of disk sizes and line optical depths.

Keywords: Line profiles -- Stars: Be -- Stars: circumstellar shells -- Stars: emission lines -- Stars: variable

• 1 Introduction
• 2 m=1 Perturbation Patterns in Isothermal Equatorial Disks
  • 2.1 The Unperturbed Disk Model
  • 2.2 m=1 Perturbation Patterns
• 3 Methods for Computing Emission Line Profiles
• 4 Emission-Line Profiles from the Unperturbed Disks
• 5 Variations of Line Profiles Due to m=1 Perturbation Patterns
• 6 Summary
• References