OISTER optical and near-infrared observations of the super-Chandrasekhar supernova candidate SNa€‰2012dn: Dust emission from the circumstellar shell

摘要

Wepresentextensivelydenseobservationsofthesuper-Chandrasekharsupernova(SCa€‰SN)candidateSNa€‰2012dnfroma?’11to+140a€‰dafterthedateofitsB-bandmaximumintheopticalandnear-infrared(NIR)wavelengthsconductedthroughtheOISTERToO(OpticalandInfraredSynergeticTelescopesforEducationandResearchTargetofOpportunity)program.TheNIRlightcurvesandcolorevolutionsupto35daysaftertheB-bandmaximumprovidedanexcellentmatchwiththoseofanotherSCa€‰SNa€‰2009dc,providingfurthersupporttothenatureofSNa€‰2012dnasanSCa€‰SN.WefoundthatSNa€‰2012dnexhibitedstrongexcessesintheNIRwavelengthsfrom30a€‰daftertheB-bandmaximum.TheH-andKs-bandlightcurvesexhibitedmuchlatermaximumdatesat40and70a€‰daftertheB-bandmaximum,respectively,comparedwiththoseofnormalSNea€‰Ia.TheH-andKs-bandlightcurvessubtractedbythoseofSNa€‰2009dcdisplayedplateauedevolutions,indicatinganNIRechofromthesurroundingdust.Thedistancetotheinnerboundaryofthedustshellislimitedto4.8a€“6.4?—10a?’2a€‰pc.Noemissionlineswerefoundinitsearlyphasespectra,suggestingthattheejectaa€“circumstellarmaterialinteractioncouldnotoccur.Ontheotherhand,wefoundnosignaturethatstronglysupportsthescenarioofdustformation.Themass-lossrateofthepre-explosionsystemisestimatedtobe10a?’6a€“10a?’5a€‰Ma??a€‰yra?’1,assumingthatthewindvelocityofthesystemis10a€“100a€‰kma€‰sa?’1,whichsuggeststhattheprogenitorofSNa€‰2012dncouldbearecurrentnovasystem.WeconcludethattheprogenitorofthisSCa€‰SNcouldbeexplainedbythesingle-degeneratescenario.