Photometric Observations of an SU UMa-type Dwarf Nova, VW Coronae Borealis, during Outbursts

摘要

WereportonphotometricobservationsofanSUUMa-typedwarfnova,VWCrB,duringtwosuperoutburstsin2001and2003andanormaloutburstin2003.Superhumpswithaperiodof0.07287(1)a€‰dwereobservedduringthe2003superoutburst.Thechangerateofthesuperhumpperiodwaspositive.Duringanormaloutburst,thereissomehintofmodulationuptoa0.2-magamplitude.However,noperiodicitywasfound.Therecurrencecyclesofthenormaloutburstandthesuperoutburst,andthedistancewereestimatedtobe$$ge50,mathrm{d}$$,$$270sim500,mathrm{d}$$,and$$690^{+230}_{-170},mathrm{pc}$$,respectively.TheserecurrencecyclesaretheusualvaluesforanSUUMa-typedwarfnovahavingthissuperhumpperiod.ThesuperhumpperiodofVWCrBwasthelongestamongthoseofSUUMastarswithpositivederivativesofthesuperhumpperiod.Thecoverageofourobservationswas,however,notsufficient,andthevariationofthe$$P_mathrm{SH}$$changerateofVWCrBisstillunknown.Asuperhumpregrowthandabrighteningwereseenneartheendoftheplateauphase.Measuringthedeviationofthestarttimingsofthebrighteningandthesuperhumpregrowth($$gt2$$daysinVWCrB)willbeakeytorevealthemechanismofthesephenomena.