Novae! - Astrophysics Research Institutemjd/Chester2016.pdf · white dwarf • Novae expected to undergo outbursts every 10,000 – 100,000 years • Recurrent novae erupt every 1-100

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


Novae:LightcurvesCanonicalnovalightcurveDarnley,2005


Novae!

•  StellarEvoluGon•  EvoluGonofclosebinarysystems

•  CataclysmicVariables•  NovaerupGons•  Novaremnants•  LinktoSNIa•  Theimportanceofnovae

Theevolu6onoftheremnantofRSOphO’Brienetal.,2006,Nature,442,279Ribeiroetal.,2009,ApJ,703,1955


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)


TheSun:RedGiant•  EventuallytheSunwill

exhaustitsHydrogenfuelsupply

•  Inana+empttoprolongitslifethecentre/coreoftheSuncontractsandheatsup.

•  AsaconsequencetheSunwillswellupandthesurfacecool

•  Diameter:>150,000,000km


TheSun:PlanetaryNebula•  Aieranother100million

yearsorso,theSunwillexhaustit’sHeliumfuelsupply

•  AgaintheSunwillexpandsignificantly

•  HoweverthisGmetheexpansionisterminalandtheSunwillejectthemajorityofitsmass

•  Becoming–briefly–agloriousplanetarynebula


TheSun:WhiteDwarf

•  OnethenebulahasdissipatedallthatisleibehindisthedensehotexGnguishedcoreoftheSun–awhitedwarf

•  AquartertoahalfoftheSun’smasspackedintoanobjectthesizeoftheEarth

•  Carbon-Oxygen‘degenerate’ma+er


TheSun:AnUnusualStar?•  90%ofstarsareless

luminousandlessmassive

•  Theonlystar(known)tosupportlife

•  Moststarsarebinarystars:–  Singlestars:1/3–  Binarystars:1/2–  Triplestars:1/8–  MulGple:1/24


BinaryStars•  Sirius–thebrighteststarin

thenightsky–isabinarysystem

•  Bothstarsarethesameage–formedtogether

•  Themoremassivestar(‘SiriusB’)evolvedquickerandisalreadyawhitedwarf

•  Theleastmassive(‘SiriusA’)issGllliketheSun

•  SeparaGon20GmesEarth-Sundistance


BinaryStars:CloseBinaries

•  OccasionallybinarysystemsareformedsuchthatthetwostarsareparGcularlyclose

•  Whenthemoremassivestarevolvesintoaredgiantthetwostarsmaycomeintocontact,orthemassivestarmayfullyencompassitscompanion


BinaryStars:CommonEnvelope•  Importantbutpoorly

understoodbinaryevoluGonarystage

•  Dragforceswithintheenvelopecausesthestarstoloseenergy

•  Thestarsmovemuchclosertogether

•  Commonenvelopephaseendswhenmostmassivestarbecomesaplanetarynebula

•  Commonenvelopeleavesawhitedwarf–mainsequencebinary

•  OrbitalseparaGonafewSolarradii

•  Gravityseverelydistortstheshapeofthemainsequencestar

•  Orbitalperiodafewhours•  Orbitalvelocityafew

thousandkm/s(1%thespeedoflight)


Novae:MassTransfer

•  AstheMSstarandtheWDaresocloseanymaterial‘lost’bytheMSstarcanbeeasilycapturedbytheWD

•  MasstransferfromtheMSstartotheWDiswhatulGmatelypowerstheNovaerupGon


Novae:AccreGonDisks

•  MateriallostbytheMSstardoesn’tfalldirectlyontotheWD

•  Thematerialspiralsinwardsineverdecreasingorbits

•  This‘accreted’materialformsadiscaroundthewhitedwarf


CataclysmicVariables•  Thismodelofclosebinary

systemswasdevelopedinthe1960sbyCrawfordandKrai

•  ThewiderCVgroupcontaining–  ClassicalNovae–  DwarfNovae–  Polars–  TypeIaSupernova?–  Manyothers!

•  VerysimilartoX-raybinaries


Novae:WhiteDwarf•  Hydrogenrichmaterial

fromMSstareventually–viathedisc–fallsontothesurfaceofthewhitedwarf

•  This‘accreted’materialiscompressedandheatedbytheintensegravitaGonalfieldoftheWD

•  TheaccretedmaterialreachestemperaturessimilartothatoftheSun’score–andthematerialbecomesdegenerate


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


Novae:MushroomCloud?

HydrogenBomb NovaModel

Simula6onoftheoutburstofUScoDrake&Orlando,2010,ApJ,720,195


Novae:ErupGon•  TheTNRpowersthenova

erupGon•  Alargeamountofthe

accretedmaterialisejectedfromthesurfaceoftheWD

•  Thesystemincreasesinluminositysignificantly,forashortGmebecomingupto1millionGmesbrighterthantheSun


Novae:Remnants•  Aierthenuclearburning

hasceasedthesystemessenGallyreturnstohowitwasbeforetheerupGon

•  TheWDandMSstarremainunscathed

•  MasstransferfromtheMSstartotheWDwillconGnue

•  TheaccreGondiscwillre-establisharoundtheWD

•  ForabriefGmeaspectacularremnantoftheerupGonwillremain


Novae:Recurrence•  AieranerupGonthe

novasystemse+lesdownandtheWDbeginstoaccumulatemorematerial

•  Typicallyaierafew1,000–1,000,000yearsitwilleruptagain

•  However,asmallgroupofnovae–therecurrents–existwithintra-erupGonGmesof10–100years


•  >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


Novae:SNIaProgenitors?•  SNIaareessenGally

standardcandles•  Theyareusedasthe

primarycosmologicaldistanceindicator

•  ProgenitorsofSNIaareunknown

•  ThoughtobethethermonucleardetonaGonofaC/OWDwhenissurpassestheChandrasekharmass(1.38Solarmasses)

•  Twopreferredscenarios–  Doubledegenerate(DD)–  Singledegenerate(SD)

•  BothscenariosrequiretheWDaccreGngma+erfromacompanion–  DD:anotherWD–  SD:astar

•  RNearetheprimeSDcandidate

•  LikelypictureisbothSDandDDpathwaysareimportant


Novae:SNIaProgenitors?


Novae:Importance

•  AllowustostudyingreatdetailmanyextremeareasofphysicsoverrelaGvelyshortGmescale–  AccreGonphysics– Massiveexplosions–  ThermonuclearreacGons–  BinarystarevoluGon


Novae:DistanceIndicators•  In1929EdwinHubble

notedthatthebrighteranovathefasteritdiminished

•  Oncecalibrated,sucharelaGonshipcanbeusedtodeterminethedistancetoanynova

•  Unfortunately,largesca+ermeansthisisonlyreallyusefulwhenonehasalargepopulaGonofnovae


Novae:Dust•  Galaxiesarepredominately

madefromthree(four)things:stars,gasanddust(darkma+er)

•  ‘Cosmic’dustisnothinglikeitsEarth-basednamesake

•  ConsistsmainlyofCarbonorSilicon‘grains’

•  WhilstnovaearenotprolificproducesofdusttheydoprovideauniqueopportunitytostudyitsproducGon


Novae:ISMEnrichment•  MoststableCarbon,

NitrogenandOxygenintheUniversecontainanequalnumberofprotonsandneutrons

•  NovaearethemainproducesofstableisotopesofC,N&Othatcontainanextraneutron(13C,15N,17O)

•  ParGcularlyimportantinnuclearmagneGcresonanceimaging(MRIscans)


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


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)


ExtragalacGcnovae


RNe/RG-novaeèSNeIa(?)•  ManymodelsnowshowRNWDmass

isgrowingwithGme•  He-flashesonhighmassWDsmay

notcausesignificantmassloss•  HighmassWDandhighaccreGon

ratedriveshorterrecurrenceGmes•  ShortrecurrenceGmesdriveWD

massgrowthrates•  PredicGonslimitrecurrenceperiods

to50daysasapproachChandrasekharlimit

•  MinorquesGonabouttheWDcomposiGon–COvs.ONe

•  Butweneedtofindtheextremesystem(s)


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”?


M31N2008-12a2008  M31transientdiscovered2009  ErupGonannounced2010  ErupGonrecovered2011  Eruptedagain2012  Spectroscopicallyconfirmed2013  iPTFdiscovererupGon2014  LTdetectspredictederupGon

•  TransientX-raydetecGons:1992,1993,and2001

•  AtleastoneopGcalerupGonin1960s


M31N2008-12a:The2010erupGon

2010 2012


M31N2008-12a:Recurrenceperiod

•  TheOpGcalErupGons–  26Dec2008–  3Dec2009–  20Nov2010–  23Oct2011–  19Oct2012–  28Nov2013–  3Oct2014

•  ExtrapolatedfromX-raydetecGons–  5Feb1992(ROSAT)–  11Jan1993(ROSAT)–  8Sep2001(XMM)



trec=351±13days



•  TheOpGcalErupGons–  26Dec2008–  3Dec2009–  20Nov2010–  23Oct2011–  19Oct2012–  28Nov2013–  3Oct2014





M31N2008-12a:Recurrenceperiodtrec=175±11days

M31N2008-12a:MissingerupGons?



•  TheOpGcalErupGons–  26Dec2008–  3Dec2009–  20Nov2010–  23Oct2011–  19Oct2012–  28Nov2013–  3Oct2014–  28Aug2015



M31N2008-12a:2014+2015erupGon


M31N2008-12a:HST


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)


10"

M31N2008-12a:HSTphotometry(F336W–U-band)


M31N2008-12a:Theremnant?!?!(?!)


M31N2008-12a:Theremnant


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


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!!!)


Documents

Novae! - Astrophysics Research Institutemjd/Chester2016.pdf · white dwarf • Novae expected to undergo outbursts every 10,000 – 100,000 years • Recurrent novae erupt every 1-100