Novae!
DrMa+DarnleyLiverpoolJohnMooresUniversity
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
Novae:IntroducGon• TheOxfordEnglish
DicGonarydefinesthetermnovaas:novan.(pl.novae)astarshowingasuddenlargeincreaseofbrightnessandthensubsiding.[LaGn,fem.ofnovus’new’,becauseoriginallythoughttobeanewstar]
• Whereas,Wikipediasays:AnovaisacataclysmicnuclearexplosionoriginaGngonthesurfaceofawhitedwarf
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:Images
M31novaoutburstDarnley,2005
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:LightcurvesCanonicalnovalightcurveDarnley,2005
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae!
• StellarEvoluGon• EvoluGonofclosebinarysystems
• CataclysmicVariables• NovaerupGons• Novaremnants• LinktoSNIa• Theimportanceofnovae
Theevolu6onoftheremnantofRSOphO’Brienetal.,2006,Nature,442,279Ribeiroetal.,2009,ApJ,703,1955
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
ClosetoHome:TheSun
• RelaGvelynormal‘mainsequence’star
• Diameter:1,392,000km(109GmestheEarth’s)
• Mass:1,989,100,000,000,000,000,000,000,000,000kg(1,300,000GmesEarth)
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
TheSun:RedGiant• EventuallytheSunwill
exhaustitsHydrogenfuelsupply
• Inana+empttoprolongitslifethecentre/coreoftheSuncontractsandheatsup.
• AsaconsequencetheSunwillswellupandthesurfacecool
• Diameter:>150,000,000km
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
TheSun:PlanetaryNebula• Aieranother100million
yearsorso,theSunwillexhaustit’sHeliumfuelsupply
• AgaintheSunwillexpandsignificantly
• HoweverthisGmetheexpansionisterminalandtheSunwillejectthemajorityofitsmass
• Becoming–briefly–agloriousplanetarynebula
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
TheSun:WhiteDwarf
• OnethenebulahasdissipatedallthatisleibehindisthedensehotexGnguishedcoreoftheSun–awhitedwarf
• AquartertoahalfoftheSun’smasspackedintoanobjectthesizeoftheEarth
• Carbon-Oxygen‘degenerate’ma+er
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
TheSun:AnUnusualStar?• 90%ofstarsareless
luminousandlessmassive
• Theonlystar(known)tosupportlife
• Moststarsarebinarystars:– Singlestars:1/3– Binarystars:1/2– Triplestars:1/8– MulGple:1/24
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
BinaryStars• Sirius–thebrighteststarin
thenightsky–isabinarysystem
• Bothstarsarethesameage–formedtogether
• Themoremassivestar(‘SiriusB’)evolvedquickerandisalreadyawhitedwarf
• Theleastmassive(‘SiriusA’)issGllliketheSun
• SeparaGon20GmesEarth-Sundistance
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
BinaryStars:CloseBinaries
• OccasionallybinarysystemsareformedsuchthatthetwostarsareparGcularlyclose
• Whenthemoremassivestarevolvesintoaredgiantthetwostarsmaycomeintocontact,orthemassivestarmayfullyencompassitscompanion
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
BinaryStars:CommonEnvelope• Importantbutpoorly
understoodbinaryevoluGonarystage
• Dragforceswithintheenvelopecausesthestarstoloseenergy
• Thestarsmovemuchclosertogether
• Commonenvelopephaseendswhenmostmassivestarbecomesaplanetarynebula
• Commonenvelopeleavesawhitedwarf–mainsequencebinary
• OrbitalseparaGonafewSolarradii
• Gravityseverelydistortstheshapeofthemainsequencestar
• Orbitalperiodafewhours• Orbitalvelocityafew
thousandkm/s(1%thespeedoflight)
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:MassTransfer
• AstheMSstarandtheWDaresocloseanymaterial‘lost’bytheMSstarcanbeeasilycapturedbytheWD
• MasstransferfromtheMSstartotheWDiswhatulGmatelypowerstheNovaerupGon
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:AccreGonDisks
• MateriallostbytheMSstardoesn’tfalldirectlyontotheWD
• Thematerialspiralsinwardsineverdecreasingorbits
• This‘accreted’materialformsadiscaroundthewhitedwarf
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
CataclysmicVariables• Thismodelofclosebinary
systemswasdevelopedinthe1960sbyCrawfordandKrai
• ThewiderCVgroupcontaining– ClassicalNovae– DwarfNovae– Polars– TypeIaSupernova?– Manyothers!
• VerysimilartoX-raybinaries
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:WhiteDwarf• Hydrogenrichmaterial
fromMSstareventually–viathedisc–fallsontothesurfaceofthewhitedwarf
• This‘accreted’materialiscompressedandheatedbytheintensegravitaGonalfieldoftheWD
• TheaccretedmaterialreachestemperaturessimilartothatoftheSun’score–andthematerialbecomesdegenerate
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Aside:Degeneracy
ClassicalMa=er• Pressureiscoupledto
temperature• Thepressureofagasisdueto
themoleculesofthatgascollidingwitheachotherandthegassescontainer
• Ifweincreasethetemperaturewegivemoreenergytothemolecules–sotheymovefaster
• Thefastertheymove,thebiggerthecollisions,sothehigherthepressure
DegenerateMa=er• Pressureisuncoupledfrom
temperature• Quantummechanicaleffect–
aconsequenceofthe‘PauliExclusionPrinciple’
• Arisesastwo(idenGcal)parGclescannotoccupythesamespaceatthesameGme
• OnlyappliesatextremelyhighpressuresanddensiGes–higherthanthoseatthecentreoftheSun
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 • @ma+darnley
Novae:TNR• Whentheaccreted
hydrogenreachesabout10millionCelsiusnuclearfusionreacGonsbegin
• ThereacGonsuseCarbonfromtheWDasacatalysttofusefourHydrogennucleiintoHelium
• Asthematerialisdegenerate–pressurecannotregulatethereacGons–hencea‘thermonuclearrunaway’ensues
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:MushroomCloud?
HydrogenBomb NovaModel
Simula6onoftheoutburstofUScoDrake&Orlando,2010,ApJ,720,195
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 • @ma+darnley
Novae:ErupGon• TheTNRpowersthenova
erupGon• Alargeamountofthe
accretedmaterialisejectedfromthesurfaceoftheWD
• Thesystemincreasesinluminositysignificantly,forashortGmebecomingupto1millionGmesbrighterthantheSun
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:Remnants• Aierthenuclearburning
hasceasedthesystemessenGallyreturnstohowitwasbeforetheerupGon
• TheWDandMSstarremainunscathed
• MasstransferfromtheMSstartotheWDwillconGnue
• TheaccreGondiscwillre-establisharoundtheWD
• ForabriefGmeaspectacularremnantoftheerupGonwillremain
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:Recurrence• AieranerupGonthe
novasystemse+lesdownandtheWDbeginstoaccumulatemorematerial
• Typicallyaierafew1,000–1,000,000yearsitwilleruptagain
• However,asmallgroupofnovae–therecurrents–existwithintra-erupGonGmesof10–100years
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
• >1observedoutburst• RecurrenceGmescales10–
100years• Secondary/donor–sub-giants
(USco)orredgiants(RSOph)• HighmassaccreGonrates• HighWDMasses• FasterupGonevoluGon• He/Nspectra• 10GalacGcsystems(aboutthe
sameinM31)• WDmassincreasing
• Onlyoneobservedoutburst• RecurrenceGmescalesfew
thousand–millionyears• Secondary/donor–main
sequencestars• LowmassaccreGonrates• RangeofWDmasses• RangeofevoluGonspeeds• FeIIandHe/Nspectra• 400GalacGcsystems(900
M31)• WDmassdecreasing
Theproblema6csystems• GKPer–classicalnovahosGngasub-giant
secondary• TPyx–recurrentnovahosGngamain
sequencesecondaryandalowmassWD,exhibiGngslowlyevolvingoutburstsandanFeIIspectra
• Plusothers!
Novae:ClassicalorRecurrent
ClassicalNovae RecurrentNovae
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 • @ma+darnley
Novae:SNIaProgenitors?• SNIaareessenGally
standardcandles• Theyareusedasthe
primarycosmologicaldistanceindicator
• ProgenitorsofSNIaareunknown
• ThoughtobethethermonucleardetonaGonofaC/OWDwhenissurpassestheChandrasekharmass(1.38Solarmasses)
• Twopreferredscenarios– Doubledegenerate(DD)– Singledegenerate(SD)
• BothscenariosrequiretheWDaccreGngma+erfromacompanion– DD:anotherWD– SD:astar
• RNearetheprimeSDcandidate
• LikelypictureisbothSDandDDpathwaysareimportant
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:SNIaProgenitors?
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:Importance
• AllowustostudyingreatdetailmanyextremeareasofphysicsoverrelaGvelyshortGmescale– AccreGonphysics– Massiveexplosions– ThermonuclearreacGons– BinarystarevoluGon
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:DistanceIndicators• In1929EdwinHubble
notedthatthebrighteranovathefasteritdiminished
• Oncecalibrated,sucharelaGonshipcanbeusedtodeterminethedistancetoanynova
• Unfortunately,largesca+ermeansthisisonlyreallyusefulwhenonehasalargepopulaGonofnovae
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:Dust• Galaxiesarepredominately
madefromthree(four)things:stars,gasanddust(darkma+er)
• ‘Cosmic’dustisnothinglikeitsEarth-basednamesake
• ConsistsmainlyofCarbonorSilicon‘grains’
• WhilstnovaearenotprolificproducesofdusttheydoprovideauniqueopportunitytostudyitsproducGon
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:ISMEnrichment• MoststableCarbon,
NitrogenandOxygenintheUniversecontainanequalnumberofprotonsandneutrons
• NovaearethemainproducesofstableisotopesofC,N&Othatcontainanextraneutron(13C,15N,17O)
• ParGcularlyimportantinnuclearmagneGcresonanceimaging(MRIscans)
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:Summary• Novaearebright–relaGvely
common–transientobjects• Atoutburst~1millionGmes
brighterthanthesun–occasionallyreachingnakedeyebrightness
• Allnovaeare‘close’binarysystems–cataclysmicvariables
• Cause:thermonuclearrunawaywithinaccretedmaterialatthesurfaceofawhitedwarf
• Novaeexpectedtoundergooutburstsevery10,000–100,000years
• Recurrentnovaeeruptevery1-100years
• Novaecanbeusedasdistanceindicators
• Canbeusedaslaboratoriestostudyalargearrayofphysics
• NovaemaybeoneoftheprogenitorsofTypeIaSupernovae
Ma+Darnley-ChesterAstronomicalSociety30thMarch2016 @ma+darnley
Novae:“VitalStaGsGcs”• Primary:WhiteDwarf
– 0.5–~1.4SolarMasses(Chandrasekharmass)
– COorONe(Mg)– PlusHeandHlayers
• Secondary:`LateType’MSstar– TypicallySolar-ishcomposiGon– Orbitalperiod1.5–8hrs–Roche
lobefilling• MassAccreGon:
– Solarmaterial–Hydrogenrich– AccreGonrate:10-9Solarmasses/
year• Luminosity:
– Quiescence:~SolarLuminosity– ErupGon:~104Solar–Eddington
luminosity
• EjectedMass:– 10-5–10-4SolarMasses– ComposiGon:depletedH,
enhancedHe/N– PossibleNeenhancementisONe
WD• RecurrencePeriod:
– 1,000–1,000,000years– 1,000soferupGonspersystem
• RecurrentNovae:– >1observederupGon– Secondary:Evolved– Orbitalperiod:>1day– HighaccreGonrate(upto10-7
Msun/yr– HighmassWD(>1.2Msun)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
ExtragalacGcnovae
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
RNe/RG-novaeèSNeIa(?)• ManymodelsnowshowRNWDmass
isgrowingwithGme• He-flashesonhighmassWDsmay
notcausesignificantmassloss• HighmassWDandhighaccreGon
ratedriveshorterrecurrenceGmes• ShortrecurrenceGmesdriveWD
massgrowthrates• PredicGonslimitrecurrenceperiods
to50daysasapproachChandrasekharlimit
• MinorquesGonabouttheWDcomposiGon–COvs.ONe
• Butweneedtofindtheextremesystem(s)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
RNe/RG-novaeèSNeIa(?)• ManymodelsnowshowRNWDmass
isgrowingwithGme• He-flashesonhighmassWDsmay
notcausesignificantmassloss• HighmassWDandhighaccreGon
ratedriveshorterrecurrenceGmes• ShortrecurrenceGmesdriveWD
massgrowthrates• PredicGonslimitrecurrenceperiods
to50daysasapproachChandrasekharlimit
• MinorquesGonabouttheWDcomposiGon–COvs.ONe
• Butweneedtofindtheextremesystem(s)
• GalacGcally– RG-nova:RSOph–20yrs– SG-nova:USco–10yrs
• LMC– LMCN1968-12a–6years(asof2016)
• M31– M31N1963-09c–5years
• Butwouldn'titbenicetofindsomethingmoreextreme?!
• Asystemmuchclosertothe50day“limit”?
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a2008 M31transientdiscovered2009 ErupGonannounced2010 ErupGonrecovered2011 Eruptedagain2012 Spectroscopicallyconfirmed2013 iPTFdiscovererupGon2014 LTdetectspredictederupGon
• TransientX-raydetecGons:1992,1993,and2001
• AtleastoneopGcalerupGonin1960s
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:The2010erupGon
2010 2012
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:Recurrenceperiod
• TheOpGcalErupGons– 26Dec2008– 3Dec2009– 20Nov2010– 23Oct2011– 19Oct2012– 28Nov2013– 3Oct2014
• ExtrapolatedfromX-raydetecGons– 5Feb1992(ROSAT)– 11Jan1993(ROSAT)– 8Sep2001(XMM)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:Recurrenceperiod
trec=351±13days
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:Recurrenceperiod
• TheOpGcalErupGons– 26Dec2008– 3Dec2009– 20Nov2010– 23Oct2011– 19Oct2012– 28Nov2013– 3Oct2014
• ExtrapolatedfromX-raydetecGons– 5Feb1992(ROSAT)– 11Jan1993(ROSAT)– 8Sep2001(XMM)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:Recurrenceperiod
M31N2008-12a:Recurrenceperiod
M31N2008-12a:Recurrenceperiodtrec=175±11days
M31N2008-12a:MissingerupGons?
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:Recurrenceperiod
• TheOpGcalErupGons– 26Dec2008– 3Dec2009– 20Nov2010– 23Oct2011– 19Oct2012– 28Nov2013– 3Oct2014– 28Aug2015
• ExtrapolatedfromX-raydetecGons– 5Feb1992(ROSAT)– 11Jan1993(ROSAT)– 8Sep2001(XMM)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:2014+2015erupGon
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:HST
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:HSTCampaign• Cycle23Proposal–
Successful(yay)– RapidSTISNUVandFUV
(lowresspectroscopy;1100-3200Angstroms)• DToO–STISFUV-MAMA–4
orbits,1visit• DToO–STISNUV-MAMA–4
orbits,splitover2visits– 4WFC3/UVISvisits
(F225W,F275W,F336W,F475W,F814W)• Visit1–3orbits-~day14• Visit2–3orbits-~day21• Visit3–3orbits-~day28• Visit4–3orbits-~day35
(~quiescence)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
10"
M31N2008-12a:HSTphotometry(F336W–U-band)
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M31N2008-12a:Theremnant?!?!(?!)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
M31N2008-12a:Theremnant
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
ModelsofM31N2008-12a• WDmass≥1.35M¤,dM/dt>
1.5×10-7M¤/yr(2013data)
• ErupGonsconsistentwithmodelsofsystemswith>1.377M¤&1.358M¤WDs(2013/14data)
• AccreGonrate>10-7M¤/year
• Massgrowthefficiency64%
• TimescaletoreachChandrasekharmass<600,000yr
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley
Conclusions/ImplicaGons/QuesGons• Arecurrentnovawithanunprecedented1year(sixmonths?)inter-erupGonGme• M31N2008-12aistheprimeSNIaSD-channelpre-explosionprogenitorcandidate
• Aresuchsystemsrareorcommon?
• Secondarytype(RGvs.SG)sGllrelaGvelyuncertain–accreGonmechanism?
• WhitedwarfcomposiGon(COvs.ONe)unknown–canweeverknowthis?
• 1sigmaconfidenceperiodsfor2016erupGons:26thFeb–19thApr&21stAug–13thOct
• DetecGonandfollow-upcampaignsforthe2016erupGon(s)comingtogether–includingLT,LCOGT,XMM,LBT(allconfirmed),plusHST,Swi+,GTC,Gemini+moreground-based(telescopedeadlinesendofMarch2016!!!)
30thMarch2016 Ma+Darnley-ChesterAstronomicalSociety @ma+darnley