Lithium, Beryllium, and Boron in RGB and AGB Starsobs · 2010. 1. 14. · Lithium...
Transcript of Lithium, Beryllium, and Boron in RGB and AGB Starsobs · 2010. 1. 14. · Lithium...
Lithium,Beryllium,andBoroninRGBandAGBStars
VerneV.SmithNa:onalOp:calAstronomyObservatory
Tucson,ArizonaUSAMixingalongtheRGBLithiumProduc:oninAGBStarsTheMysteriousLithium‐richK‐giants
LithiumDeple:on,Mixing,andStellarEvolu:on:SomeHistory
• Bonsack(1959)• Wallerstein(1964)‐”CapellaF&G”
Iben(1965)
LithiumDeple:oninGiants—FirstAscentandClump
• Brownetal.(1989):Lithiumsurveyof644G‐Kgiants.
• ~DiskGiants• ~1%are“Lirich”• Distribu:onoftherestsuggestextra‐mixingontheRGB
LithiumDeple:oninMetal‐PoorFieldRedGiants
[Fe/H]=‐2to‐1. Mixing/dilu:onatRGB~20x—agreementwithmodels. Extramixingneartheloca:onoftheRGBBump.
LogL/L(Sun)
0 1 2 3
Graionetal.2000
LithiuminNGC6397• Kornetal.(2007)diffusionandmixing.
Lindetal.(2009)
GarciaHernandezetal.(2009)
LithiuminDiskRedGiantStars
• Lagardeetal.(2009)–Poster.
BoronAbundancesandMixinginHyadesRedGiants
• Duncanetal.(1998)—HSTGHRS.
• TwoHyadesgiants+BetaGem(K0).
• Deple:onfactorof~10,inagreementwithstandardmixing.
• HyadescomparisonF‐dwarf.
LithiuminAGBStars:StellarNucleosynthesis
• McKellar(1940):Strongλ6707LiIinthecarbonstarWZCas.
”OnegoodcomparisonstarexaminedwasRSCygni,typeN0pe,inthespectrumofwhichtheequivalentwidthofthesodiumlineswasmeasured53angstromunits.Itthusappearsthatprobablythereasonfortheoccurrenceoftheλ6708lineinthespectrumofWZCassiopeiaeisanunusuallyhighabundanceoflithiuminthisstar.”
• Torres‐Peimbert&Wallerstein(1966):
C‐starsurvey.16outof30diskC‐starshavesubstan:allithium,0outof5high‐velocityC‐starshavedetectableLiI—masseffect.Li/Caabundancera:osvaryof6orders‐of‐magnitude.
• Keenan(1967):S‐star–TSgr.
PlacingLithiumAbundancesinAGBStarsinaStellarEvolu:onaryContext
• Boesgaard(1970)Quan:ta:veLi/CainSstars.
Interpreta:on• Cameron(1955)3He(α,γ)7Be7Be(e‐,ν)7Li Cameron&Fowler(1971)Associa:onwithAGBthermalpulses(TP‐AGB). Scalo,Despain,Ulrich(1975)HotBoiomEnvelopes.
LithiumandAGBHot‐BoiomBurningintheMagellanicClouds
• Smith&Lambert(1989;1990)• Plez,Smith,&Lambert(1993)
• Smithetal.(1995)
ChemicalEvolu:onmodelscanincludethissynthesis,e.g.Maieuccietal.(1996)
Hot‐BoiomBurningasaLinkbetweenCarbonStarsandtheLuminousS‐stars
• Smithetal.(1995)
• Drivenbythesugges:oninWood,Bessell,&Fox(1983)
BacktotheMilkyWaywithAGBHot‐BoiomBurning
• Garcia‐Hernandezetal.(2007):MassiveO‐richAGBstars.
• Vantureetal.(2008):Tc,Li,galac:clat.
K‐GiantswithEnhancedLithiumAbundances
• Evolu:onarystatus?• WheredoestheLicomefrom? Morehistory
May1980
Proper:esoftheLi‐richRedGiants
• Brownetal.(1989):
~1%ofG‐Kgiants.
• Fekel&Balachandran(1993):
Asignificantfrac:onofLi‐richgiantsarerapidrotators.
• delaRezaetal.(1996):
CircumstellardustfromIRAScolors.
• Charbonnel&Balachandran(2000):Possibleassocia:onoftheLi‐richgiantswiththeLuminosityBump.
• Lagardeetal.(2009)
Lithium‐richRedGiantsareinGlobularClusters,too!
• Carney,Fry,&Gonzalez(1998):M5(Log[L/Lsun]=3.1)
• Smith,Shetrone,&Keane(1999):NGC362
• Krayetal.(1999):M5
Log(L/Lsun)=2.9
Log(L/Lsun)=3.3
CanSub‐stellarInges:onAffectRota:onorLithium?
• Carlbergetal.(2009):Modellingrota:onfromassimila:on.
Lithiumabundanceswouldbeaffected—dependsonra:oofplanetmasstoconvec:veenvelopemass,orchemicalfrac:ona:on.
TidalDecayandInges:onOccurs
• Jacksonetal.(2009)
• Model:dalevolu:on.
• NoteAge–minimumsemi‐majoraxisrela:on.
Beryllium(orBoron)canProvideConstraintstotheLithium‐richPhenomenon
• Cas:lhoetal.(1999):BerylliumabundancesintwoLi‐richK‐giants.
• Berylliumisdepletedaspredictedbystellarevolu:on.
• Meloetal.(2005):Berylliumin7Li‐richgiants.Sameresult.
Summary/Conclusions
• Evolu:onalongtheRGB—firstdredge‐upfollowedbyextra‐mixingattheLuminosityBump.Lithiumcreated/destroyed.Lithiumisasensi:veprobe,moresothanBerylliumorBoron.Inaperfectworld,we’dhaveall3.
• AGBandHot‐BoiomBurning.Lithiumisagainamonitor.ConversionofC‐starstoS‐stars,primary14N.
• TheLithium‐richGiants.S:llamystery.Internalversusexternalprocesses.Couldbeacomplexmixture.
SummaryII• RGB/AGBmixingprocesses+nucleosynthesis.• BBN,CosmicRays,NewPhysics(?).
• Main‐Sequencestarmicrophysics.
• Connec:onstoexo‐planets.• WithLithium,Beryllium,andBoronwehaveitall;wecanbeatonewithNature.
SummaryII• RGB/AGBmixingprocesses+nucleosynthesis.• BBN,CosmicRays,NewPhysics(?).• Main‐Sequencestarmicrophysics.• Connec:onstoexo‐planets.• WithLithium,Beryllium,andBoronwehaveitall;wecanbeatonewithNature.
• “IamattwowithNature”–WoodyAllen• So…“WeareatthreewithNature”‐LiBeB