Observational Properties of Type II Plateau Supernovae

We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties, from the $^{56}$Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, $^{56}$Ni poor SNe (e.g. SN 1997D). We pro

arXiv:astro-ph/0310056v1 2 Oct 2003

We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties, from the $^{56}$Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, $^{56}$Ni poor SNe (e.g. SN 1997D). We pro

2A.Pastorelloetal.

decays.Thesampleincludes6Nipoor(<10 2M⊙)SNe,5intermediateNimass(1–5×10 2M⊙)SNeand5morerichNimass(>7×10 2M⊙)events.

Table1.MaindataoftheselectedSNeII–P

SN

1987A18.490.602446849.82SAAO1999br31.190.082451278[5],[8]1992am36.740.4424487991994N33.340.132449451

1996W31.950.702450180[12]1999eu31.080.092451394[8]2002gd33.090.222452552[9]

( )referenceforspectro–photometricdata[9][8]µAVt0(JD)ref.( )[9]1996an31.500.162450222

InTab.1welistthemaindataabouttheselectedSNe(seealsoRamina,LaureaThesis,2003,unpublishedandreferencestherein).Whenthedistancemodulusµisobtainedfromthehostgalaxyrecessionvelocity,H0hasbeenassumedtobeequalto65kms 1Mpc 1.ThetotalextinctionreportedinTab.1isthesumofthehostgalaxyreddeningplustheGalacticcontribu-tion,fromSchlegeletal.[11].MoredetailsontheestimateddistancesandinterstellarextinctionareinRamina[LaureaThesis,2003,unpublished].Fig.1.Spectraoflow–luminositySNeII–Pat～100daysaftertheexplosion.

We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties, from the $^{56}$Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, $^{56}$Ni poor SNe (e.g. SN 1997D). We pro

ObservationalPropertiesofTypeIIPlateauSupernovae3

1.1FaintSNeII–P

SN1997D

[13,1]istheprototypeofahomogeneousgroupofCC–SNewithuniqueobservationalproperties.Thelightcurves,showing atplateauxlasting～90–110days,areunderluminousatallepochs,andtheirspectra,redderthan“typical”SNeII–P,showstrongandnarrowP–Cygnifeaturesindicatingverysmallexpansionvelocities(～1000kms 1attheendoftheplateauphase,seeFig.1).InPastorelloetal.[8]andZampierietal.[14]othersimilarSNewerediscussed(SNe1994N,1999br,1999euand2001dc).Thedatabasehasbeenrecentlyenrichedbythediscoveryofawellrepresentativeevent,SN2003Z,extensivelymonitoredatTNG4.ThisSNprovidesaverygoodexampleofthespectro–photometricevolutionoflow–luminositySNe(seeFig.2).TheSNwasobservedbothinspectroscopyandphotometryduringthephotosphericphase,andobservationsduringthenebularphase,usefultoestimatethe56Nimass,arestillinprogress.Preliminarylate–timephotometrysuggeststhatSN2003Zejected0.006M⊙of56Ni.Wesuggestthatlow–luminosityeventsmayoccuratanintrinsicallyhighfrequency.

Fig.2.Photometricandspectroscopicevolutionofthelow–luminositySN2003Z.Un lteredmeasurementsandVSNET(http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/)dataarealsoreported.

TheobservedpropertiesofthefaintCC–SNeareconsistentwithverysmallejected56Nimass(<10 3M⊙)andlowexplosionenergy( 1051erg,[14]).Thissuggestshigh–massprogenitors(MMS>20–25M⊙)forwhichsigni cantfall–backmighthaveoccurred([14]andZampierietal.,theseProceedings).

1.2NormalSNeII–P

Thesamplecontainsalsoanumberof“normal”andhighluminosityeventscoveringalargerangeofphysicalproperties(e.g.Nimass,explosionenergy,

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We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties, from the $^{56}$Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, $^{56}$Ni poor SNe (e.g. SN 1997D). We pro

4A.Pastorelloet

al.

Fig.3.Top:LuminosityevolutionofourselectedsampleofSNeII–P.Bottom:ex-pansionvelocitiesobtainedfromtheblueshiftoftheminimumofScIIlines.Adoptedcoloursare:redforfaint1997D–likeSNe,magentaforintermediate–luminositySNe,blackfornormalandhighluminosityevents;blue(solidline)isSN1987A.

ejectedmass).Evenifweobservealargespreadbothinluminosity(2–20×1042ergs 1)andinexpansionvelocity(3000–5000kms 1atthebeginningofrecombination),theseSNenevershowtheextremepropertiesofSN1997Dandotherfaintevents.Zampierietal.(theseProceedings)suggestthattheejectedenvelopemassisintherange12–26M⊙,withnode nitetendencytovarywiththeotherSNparameters.

PeculiaristhecaseofSN2002gd,wellobservedduringtheplateau,thanlostbehindthesun.Theplateauluminosityisrelativelyhigh,buttheex-pansionvelocitydeducedfromtheP–Cygniminimaofspectrallinesissmall,

We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties, from the $^{56}$Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, $^{56}$Ni poor SNe (e.g. SN 1997D). We pro

ObservationalPropertiesofTypeIIPlateauSupernovae5

closetothatoffaintestSNeII–P.ThisSNwasrecentlyobservedandourpreliminaryphotometrysuggestsanunusuallystrongpost–plateauluminos-itydecrease.Wemayexplainitwithaverylowamountof56Niejected(<10 3M⊙).Or,alternatively,dustformationintotheejectamightabsorbthelightatopticalwavelengths,leadingustounderestimatethe56Nimass.Be-causeofitspeculiarbehaviour,otherlate–timeobservationsarerequiredtobetterunderstandthiseventandbeforethatanysystematicanalysisofitspropertiescanbeperformed.

2TheheterogeneousfamilyofSNeII–P

Acomparisonamongthepseudo–bolometriclightcurvesfortheSNeII–PofoursampleisshowninFig.3.Thelightcurvesappeartobeheterogeneousinshapeandluminosityatallepochs.Inparticulartheexponentialtailsarepoweredbyverydi erentamountsof56Co(0.002–0.3M⊙).It’sremarkablethatthelow–luminositySNearefainteratallstagesthanallotherSNeshowninFig.3.

Alsotheevolutionoftheexpansionvelocity,obtainedmeasuringtheblueshiftoftheminimaoftheFeIIlines(seeFig.3)showsalargespreadatallepochs,rangingf …… 此处隐藏：4968字，全部文档内容请下载后查看。喜欢就下载吧 ……