Completion of Unification Model for the Outburst Mechanism of Dwarf Novae

矮新星是一种喷发变星，每隔几周到几个月就会爆发一次3-5级的重复爆发。矮星属于接近的双星系统，称为激变变星，其中充满罗氏叶的红矮星次级星失去质量，而白矮星主星通过吸积盘将其吸积起来。现在人们普遍认为，矮新星的爆发可能是由激变变星中吸积盘的不稳定性引起的，即由作者(Osaki，1974)于1974年首次提出的盘不稳定性模型。各种矮新星的爆发光曲线具有丰富的多样性。在圆盘不稳定模型的基本框架内，作者于1996年提出了一个矮新星爆发的统一模型。本研究的目的是从不同的角度对这一模式进行研究，以完成这一课题。将对本学期的研究成果进行总结。…附近的X射线日冕发射模型激变变星中的更多白矮星已知，如果吸积率低于某一临界值，则由于边界层的热不稳定性，在吸积的白矮星周围会产生近球形的热冕。建立了该日冕的稳态模型，计算了X射线能谱随质量供给率的变化。已经发现，日冕的热能通过电子传导向下传输到白矮星表面附近较密集的区域，在那里以X射线辐射的形式发射出来。盘提供的大约5%的物质可能会以恒星风的形式离开系统。矮新星爆发机制统一模型的完善本人在各种国际会议和研讨会上提出了我们在圆盘不稳定范式下的矮新星爆发机制统一模型。它得到了普遍的接受，但也有一些批评，这些都将有助于这一理论的进一步发展。较少

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