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