General Discussion

Abstract

This dissertation tests the disk-instability model as for four kinds of recently detected light variations in dwarf novae. This chapter summarizes the contents in Chaps. 3–5 from this point of view and give discussion. I briefly introduce alternative hypothesis of dwarf-nova outbursts and compare it with the disk-instability model. Throughout this work, it becomes clear that it is important to consider new aspects which are not included in existing works about the disk instability in order to systematically explain a rich variety in dwarf-nova outbursts. Additionally, I discuss about the evolutionary stage of dwarf novae since the studies on outbursts in dwarf novae are more or less related to the evolution of low-mass binary systems. Furthermore, I discuss the disk-instability model in other kinds of systems like low-mass X-ray binaries. There are a lot of astronomical objects showing outbursts and having accretion disks in the universe. The accretion disk in dwarf novae is the simplest, so that the results in this dissertation may be applicable for other kinds of systems.KeywordsDwarf novaeAccretion disksOutburstsInstabilityBinary evolutionX-ray binaries