---
author:
- |
    Soon-Wook [Kim]{},[^1]\
    [*Department of Astronomy, Seoul National University, 151-742, Seoul, Korea*]{}\
    [*E-mail: skim@astro.snu.ac.kr*]{}\
    J. Craig [Wheeler]{},\
    [*Department of Astronomy, University of Texas at Austin, RLM 15.308, Austin, TX 78712-1083, U.S.A.*]{}\
    and\
    Shin [Mineshige]{}\
    [*Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502*]{}
title: 'Black-Hole X-Ray Transients: The Effect of Irradiation on Time-Dependent Accretion Disk Structure'
---

Introduction
============

There is now broad recognition that the most common form of black-hole binary candidates in the Galaxy are transients (Chen et al. 1997). The cause of the primary rise in outburst is most likely to be due to the disk thermal instability associated with the ionization of hydrogen and helium (Cannizzo et al. 1982; Mineshige, Wheeler 1989). The disk-instability model can also produce ultra-soft X-rays ($\lta$ keV) and a strong correlation between the optical and X-rays in the outburst evolution (Mineshige et al. 1990a). There remain many interesting issues, however. The original disk-instability model (without irradiation) failed to produce a plateau in the $V$-magnitude like that 100–200 days after the peak in some systems. Although the disk-instability model can to account for the beautiful exponential decays (Cannizzo et al. 1995), it has difficulty in producing 