Published in "QSO Absorption Lines", Space Telescope Science Institute Symposium Series 2, 1987, eds. J. C. Blades, D. A. Turnshek and C. A. Norman

Abstract. The current status of observations pertaining to BAL QSOs is reviewed. Evidence which motivates a simple disk-like geometric and kinematic model for the BAL region is presented. This includes constraints on distance, covering factor and the acceleration/deceleration of the BAL region flow. Evidence which suggests that BAL region abundances are enhanced relative to solar values is also reviewed. The relation between this model and models for QSO broad and narrow emission line regions is discussed. Finally, evidence which suggests that some of the narrow absorption line systems seen in QSO spectra are intrinsic or caused by the BAL phenomenon is considered.

Table of Contents

• INTRODUCTION
• OBSERVATIONS
• Fraction of QSOs with BALs
• Characteristics of BALs
• Correlation Between BAL and Broad Emission Line Profiles
• Emission Line Properties of BAL QSOs
• Radio Properties of BAL QSOs
• Optical Polarization and Variability of BAL QSOs
• BAL Trough Variability
• Imaging of BAL QSOs
• MODEL PROPERTIES
• The Starting Point of a Model
• The Size Scale of the BAL Region
• The Global BAL Region Covering Factor
• The Large and Small Scale Geometry of the BAL Region
• Is the BAL Region Flow Accelerating or Decelerating?
• Abundances and Ionization in the BAL Region
• Relation Between the BAL Region and the Emission Line Regions
• RELATION TO THE NARROW ABSORPTION LINES
• Similarity Between the BALs and the Narrow Absorption Lines
• Z_abs Near Z_em Systems
• Highly Displaced Metal Line Systems
• Damped Ly-α Systems
• Ly-α Forest Systems
• The Effect of the BAL Region Outflow
• FUTURE WORK
• REFERENCES