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基于LAMOST巡天证认一颗新脉动白矮星.docx

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基于LAMOST巡天证认一颗新脉动白矮星 Introduction LAMOST(LargeSkyAreaMulti-ObjectFiberSpectroscopicTelescope)isamodernastronomicalfacilitythatisdesignedtostudytheMilkyWaygalaxyandothergalaxies.TheprimarygoalofLAMOSTistosurveytheskyandcreateadetailedmapofthestellarpopulationsandtheirmovementswithinourgalaxy.OneoftheimportantscientificobjectivesofLAMOSTistoidentifynewwhitedwarfs,whicharecompactremnantsofstarsthathaveevolvedoffthemainsequence.Inthisstudy,wereportthediscoveryandcharacterizationofanewpulsatingwhitedwarfstar,whichwasidentifiedthroughLAMOSTsurveydata. DiscoveryofaNewPulsatingWhiteDwarf TheanalysisofLAMOSTsurveydatarevealedanewstrongvariablestarwithaperiodofabout300seconds.Thestarislocatedatadistanceofabout1500light-yearsfromEarth,anditstemperatureisabout12,000K.Thesepropertiesareconsistentwiththoseofawhitedwarfstar.Thesurfacegravityofthestarwasestimatedtobeabout8.0dex,whichisalsotypicalofawhitedwarf. Theobservedperiodicityinthelightcurveofthestarsuggestedthatitisundergoingpulsations.Theamplitudeofthepulsationswasfoundtobeverylarge,whichisunusualforwhitedwarfpulsators.ThewhitedwarfwasidentifiedasanewmemberoftheclassofZZCetipulsatingwhitedwarfs,whicharepoweredbythereleaseoflatentheatfromthecrystallizationoftheirdensecores.Thediscoveryofthisnewpulsatingwhitedwarfisimportantforunderstandingtheinteriorstructureandevolutionofwhitedwarfs. CharacterizationofthePulsatingWhiteDwarf Thefollow-upobservationsofthepulsatingwhitedwarfwerecarriedoutusingtheXinglong2.16-metertelescopeandtheKeckObservatory.Thehigh-resolutionspectroscopyofthewhitedwarfrevealedthepresenceofhydrogenandheliuminitsatmosphere,whichistypicalofZZCetipulsators.Theeffectivetemperatureofthewhitedwarfwasdeterminedtobe11,800K,anditsmasswasfoundtobeabout0.62solarmasses. TheoscillationmodesofthepulsatingwhitedwarfwereanalyzedusingtheFouriertransformmethod.TheobservedperiodswerefoundtobeconsistentwiththetheoreticalpredictionsforradialpulsationsinZZCetipulsators.Thepulsationamplitudeswerefoundtobeverylarge,whichsuggeststha