THEORY OF ACCRETION DISKS .2. APPLICATION TO OBSERVED SYSTEMS

Accretion disks are important for many astrophysical phenomena, includ ing galactic nuclei, interacting binary stars, and young stellar objec ts. The central issue in the theory of accretion disks is to identify the dominant mechanisms that regulate angular momentum transfer and ma ss flow in a variety of contexts. In the first part of this review, we described some recent advances in the study of the physical processes that may be present in accretion disks. Concurrent with these theoret ical developments, the arrival of high-resolution astronomical instrum ents has led to explosive progress on the observational side. In many cases, the study of accretion disks has evolved from their inferred pr esence based on circumstantial. evidence to direct imaging and detaile d spectral analyses. Here, we summarize the theoretical interpretation of these data. We review the constraints that may be imposed on the e fficiency and nature of angular momentum transfer processes in a varie ty of astrophysical contexts.