Evolution of Accretion Disks with Mass Evaporation during the Quiescence of WZ Sge-Type Dwarf Novae and X-Ray Novae

摘要

WeproposeanewscenariofordiskevolutionduringthequiescenceofWZSge-typedwarfnovaeandX-raynovae.Aholecreatedbyevaporationoftheinnerdiskmaterialsteadilyexpandstowardslargerradii,eventuallyremovingthermallyunstableportionsofthedisk.Thediskis,however,notinasteadystate,sinceacertainamountofangularmomentumiscontinuouslybroughtinbyanincomingstream,whereasangular-momentumlossesduetotheevaporationandtothetidalactionbyacompanionstararelikelytobesmallinthequiescence.Accordingly,thetotalangularmomentumofthediskmonotonicallyincreases,whereasanincreaseinthediskmassissomewhatslowerbecauseofthemassevaporation.Thisresultsinanexpansionofthediskandanaccumulationofmassintheoutermostpartofthedisk.Thequiescencewillbeterminatedifathermalinstabilityisignitedbeforethediskexpandstothecriticalradiusforthe3:1resonancebetweenKeplerandorbitalangularfrequencies.Ifnot,superhumpsareexpectedduringquiescence.