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Abundance Patterns to Probe Stellar Nucleosynthesis and Chemical Evolution

Abundance Patterns to Probe Stellar Nucleosynthesis and Chemical Evolution. Francesca Primas. Setting the Stage. 1. High-z universe, i.e. looking at objects in their infancy stages. DLA: dominant reservoir of neutral baryons measure the mean metallicity in HI (5< z < 0).

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Abundance Patterns to Probe Stellar Nucleosynthesis and Chemical Evolution

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  1. Abundance Patterns to ProbeStellar Nucleosynthesisand Chemical Evolution Francesca Primas

  2. Setting the Stage 1. High-z universe, i.e. looking at objects in their infancy stages • DLA: dominant reservoir of neutral baryons • measure the mean metallicity in HI (5< z < 0) 2. Nearby universe, i.e. looking at the fossilized imprint left by the first generations of stars • EMP: precious witnesses of the early evolutionary phases of our Galaxy Identify the imprint left by the first SNe explosions Old Metal-poor [Fe/H] = log(Fe/H)* - log(Fe/H)sun

  3. Stellar Nucleosynthesis light elements BBN, CR spallation alpha and iron-group SN physics (time delays) and SN imprint heavies n-capture

  4. The Light Elements Li Be B (670.7nm, 313.0nm, 250.0nm) • Implications for cosmology BBN vs IBBN (Li) • Implications for stellar structure Li T=2.5x106K Be T=3.0x106K B T=5.0x106K • Implications for nucleosynthesis and cosmic-ray physics classical spallation (Reeves et al. 1970) ? primary ? neutrino-spallation (11B) ?

  5. Cayrel et al. 2004 Latest Abundances McWilliam et al 1995

  6. What Have We Learned • well defined trends with low dispersion all the way to the most MP stars • as quality , the dispersion  • -- SMALL in most cases: 0.05-0.15dex • -- THINNEST of all: Cr,Ti • -- MOST DISPERSED: Mn (~0.2dex for [Fe/H]<-3) • there is NO unambiguous detection of products of PISN • constraints on SN II yields: M~15-50 Msun, but also up to 100Msun or hypernovae are able to reproduce the observed • trends (mixing and fallback) Abundancedispersion s=0.05dex! Cayrel et al. (2004) data

  7. Stellar Highlights HE 0107-5240 ([Fe/H]=-5.3)and HE 1327-2326 ([Fe/H]=-5.5 (large[C/Fe], but different in N, Na, Mg, Al) C-rich metal-poor stars: 20-30% (?) r-process rich stars

  8. The Detailed Picture CS 22892-052 Sneden et al. 2003 CS 31082-001 Hill et al. 2002 Galaxy at z=2.63 Prochaska et al. 2003

  9. Hill et al. 2002 1. Does Os really deviate from the solar r-process pattern ? Not anymore after new gf value (Ivarsson et al. 2003) ==> Os=Ir 2. Still missing input atomic physics for Ho, Lu, and Yb!

  10. What’s next ? --->Atomic physics and (best) abundance indicators --->Model atmospheres and theory of line formation LTE vs NLTE 1D vs 3D Asplund 2005 (ARAA) Asplund 2002

  11. The End

  12. 1D vs 3D CNO Fe Collet et al 2006

  13. Cosmo-chronometry EMP = old ?? Not quite, presumably old ==> age In r-process rich stars: Dt = 46.67(log(Th/S)o - log(Th/S)obs ) Problem: evaluation of the log(Th/S)o based on the assumption that the r-process is universal [ cf. Cowan (pro) and Goriely (con) ] Warning: actinides and lower-mass r-nuclei may vary strongly (despite the constancy for Z=56-82) [ cf. Hill et al. 2002, Honda et al. 2003] Th (and U) seem to be over-abundant: log(Th/Eu) = -0.22 (wrt ~ -0.6! for similar stars)

  14. Cosmo-chronometry Age difference ?NO, otherwise CS 31082-001 would have a negative age, compared to the other n-rich stars ! Ab initio enhancement ?IF SO, r-process may not be universal ! Th/Eu =? a reliable chronometer CS 31082-001:Th and U were detected and used Dt = 21.76(log(U/Th)o - log(U/Th)obs) +similar ionization and excitation potentials --> errors largely cancel out + initial production ratio: more robust against variations in n-exposure (nuclear reaction network code containing more than 3500 isotopes with all relevant reactions! ) Nilsson et al. 2002a,b Goriely & Arnould 2001 ! 8 Th lines, each with gf determined better than 0.08dex 1 U line with gf determined better than 0.06dex log(U/Th)o = 0.50 (0.02) Age = 14.0 +/- 2.4 Gyr log(U/Th)obs = -0.74 (0.15) … -0.94 (0.11)

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