Emission-Line Eclipse Mapping of Velocity Fields in a Dwarf-Nova Accretion Disk

摘要

Weproposeanewmethod,emission-lineeclipsemapping,tomapthevelocityfieldsofanaccretiondiskinpositionspace.Quiescentdwarfnovaeusuallyexhibitdouble-peakedemission-lineprofilesbecauseofdiskrotation.Sinceapartofadiskhavingadifferentline-of-sightvelocityissuccessivelyobscuredbyacompanionineclipsingsystems,theyshowtime-varyinglineprofiles.Wecalculatedthetimechangesoftheemission-lineprofiles,assumingKeplerianrotationfields($$v_varphiproptor^{-1/2}$$with$$r$$beingthedistancefromthediskcenter)andanemissivitydistributionof$$jproptor^{-3/2}$$.We,then,appliedtheusualeclipsemappingtechniquetothelightcurvesateachof12a€“24wavelengthsacrossthelinecentertomaptheregionwiththesameline-of-sightvelocity.Thereconstructedimagestypicallyexhibitaa€?two-eyea€?patternforhighline-of-sightvelocities,andwecanrecovertherelation,$$v_varphiproptod^{-1/2}$$,ontheassumptionofanaxisymmetricdisk,where$$d$$istheseparationbetweenthetwoa€?eyesa€?.WewillbeabletoprobetheKeplerianrotationlaw,themostfundamentalassumptionadoptedinmanydiskmodels,byhigh-speedspectroscopicobservationswith8-mclasstelescopes.