Completion of Unification Model for the Outburst Mechanism of Dwarf Novae

矮新星是一种爆发变星，每隔几周到几个月就会出现3-5等的重复爆发。矮新星属于一种被称为灾变变星的紧密双星系统，其中一颗充满罗氏叶的红矮星次级恒星失去质量，一颗白矮星主星通过吸积盘吸积它。目前人们普遍认为，矮新星爆发可能是由灾难性变星吸积盘的不稳定性引起的，即本文作者（Osaki, 1974）在1974年首次提出的吸积盘不稳定性模型。各种矮新星的爆发光曲线有丰富的变化。本文作者于1996年在盘不稳定模型的基本框架内提出了矮新星爆发的统一模型。本研究的目的是通过从不同的角度研究这个模型来完成这个项目。总结本学期的研究成果。突变变星中白矮星的x射线发射日冕模型我们知道，当吸积速率低于某一临界值时，由于边界层的热不稳定性，在吸积白矮星周围会产生一个接近球形的热日冕。建立了该日冕的稳态模型，并计算了其x射线谱作为质量供给率的函数。已经发现，日冕的热能通过电子传导向下传递到白矮星表面附近密度较大的区域，在那里以x射线辐射的形式发射出来。大约有5%的圆盘提供的物质会以恒星风的形式离开星系。矮新星爆发机制统一模型的完成我本人在各种国际研讨会和研讨会上提出了在盘不稳定范式下矮新星爆发机制的统一模型。这一理论得到了普遍的热烈接受，但有时也提出了一些批评，这些批评对这一理论的进一步发展是有益的。少

Dwarf novae are eruptive variables showing repetitive outbursts of amplitudes of 3-5 magnitude once every a few weeks to months. Dwarf novae belong to close binary systems called cataclysmic variable stars in which a Roche-lobe filling red dwarf secondary star loses mass and a white dwarf primary star accretes it via an accretion disk. It is now widely accepted that outbursts of dwarf novae may be caused by the instability in accretion disks in cataclysmic variable stars: i.e., the disk instability model which was first proposed by the present author (Osaki, 1974) in 1974. There is a rich variety in outburst light curves of various dwarf novae. A unification model for dwarf nova outbursts was proposed by the present author in 1996 within the basic framework of the disk instability model. The purpose of this research is to complete this project by investigating this model from various standpoint. Research results in this term will be summarized.1. A model of X-ray emitting coronae aroun … More d a white dwarf in cataclysmic variable starsIt is known that a nearly spherical hot corona is produced around accreting white dwarfs because of thermal instability at the boundary layer if the accretion rate is below some critical value. A steady state model of this corona is constructed and the X-ray spectra are calculated as functions of the mass supply rate. It has been found that the thermal energy of the corona is transported downward by electron conduction to the denser area near the surface of the white dwarf, where it is emitted as X-ray radiation. Around 5% of the matter supplied by the disk could leave the system as stellar wind.2. Completion of unification model for the outburst mechanism of dwarf novaeOur unification model for the outburst mechanism of dwarf novae within the disk instability paradigm was presented by myself in various international symposia and workshops. It was generally accepted warmly but several criticisms were also raised sometime and these will be useful for further development of this theory. Less