Photometric Study of KR Aurigae during the High State in 2001

摘要

WephotometricallyobservedtheVYScl-typecataclysmicvariableKRAurigaeafteritsfinalrisefromafadingepisodein2000a€“2001.Atime-resolvedobservationrevealedthatthelightcurveisdominatedbyapersistentshort-termvariationwithtime-scalesofminutestotensofminutes.Onsomenights,quasi-periodicvariationswithperiodsof10a€“15a€‰minwereobserved.Nocoherentvariationwasdetected.Thepowerspectraldensityofthevariationhasapower-lawcomponent($$f^{-1.63}$$).Thetemporalpropertiesoftheshort-termvariationsinKRAurpresentadditionalsupportforthepossibilitythatflickeringinCVsmaybebetterunderstoodastheresultofaself-organizedcriticalstate,asinblack-holecandidates.Thelightcurvelacksa€?superhumpa€?-typesignals,whicharerelativelyfrequentlyseeninVYScl-typesystemsandwhicharesuggestedtoarisefromatidalinstabilityoftheaccretiondiskinducedbychangingmass-transferrates.ThepresentobservationsuggestsaborderlineofsuperhumpexcitationinVYScl-typestarsbetweenmassratiosof$$q=0.43$$(MVLyr)and$$q=0.60$$(KRAur).