1. New Constraints on Neutron- Capture Nucleosynthesis Processes Inese I. Ivans California Institute of Technology Hubble Fellows Symposium April 7, 2005

2. Lanthanides Actinides 1 34 1112 19202122232425 3738403941 55 4243 745657727375 87 62 88 59 9590 5863 89 60 9491 106105104 61 9392 107108 9697 76 6768666564 1031021019910098 114113112111110 717069 116115 2627 44 28 45 77 46 7978 29 47 30 48 80 49 81 31 13 50 82 1415 3233 51 8483 1718 3435 53 36 5452 8685 118117 56 16 87910 2 H Li NaMg KCaScTi RbSrYZrNb V CsBa Fr La RaAc HfTa Ce W PrNd CrMn Tc Re Th Fe Ru Os Pa Co Rh Ir Pm Ni Pd Pt U Cu Np Au Ag Zn Cd Fm Hg Es Ga Sn Cm BiPb PSiAl In Bk Tl Cf Sb PoAtRn ErHo SCl Ge Ar AsSeBr B Kr TeIXe He CNOFNeBe Tm Md Yb No Lu Lr Sm Pu Eu Am GdTbDy 109 yy Xx Mo A Periodic Table of the Elements Xx: element symbol; yy: atomic number CR BBN CR (+/-) neutron-capture 4

3. (Rolfs & Rodney 1988) Chart of Nuclides

4. Solar System Abundance Distribution =Z+N (Cowley 1999) =Z+N

5. Solar System Abundance Distribution =Z+N SNeII SNeIa O,Mg massive Si,Ca,Ti less massive Th,U  =Z+N AGB Sr,Y,Zr Ba,La Pb,Bi massive less massive

6. Happened very early in Galactic times: some very metal-poor stars are enormously rich in elements created in r -process (eg. [Fe/H] ~ -3.1 => 1/1250 [Fe/H] sun ) Sneden, Cowan, Ivans et al 2002 Created in SNe II Maybe Probably Likely Perhaps... The site of the rapid neutron-capture process?

7. Happened over long timescales and range of metallicities and in equal measure in the disk and halo Created in SNe II Maybe Probably Likely Perhaps... “universality” of the r-process? (Cowan, Sneden, Ivans et al 2001)

8. (Cowan et al 2002) “universality” of the r-process maybe not so universal BD+17 o 3248 SS-r poor agree- ment with Z<56 &/or heavies

9. (Rolfs & Rodney 1988) Lead & bismuth: the end of the line for the s-process

10. In low mass (1-3M sun ) AGB stars, neutrons: 12 C(p,  ) 13 N(e+, ) 13 C( ,n) 16 O seeds: Fe With decreasing metallicity, n ~ constant Fe decreasing => increasing n/Fe =>  s-process dist’n (1998 Gallino et al.)

11. (Ivans et al. submitted) CS29497-030 Largest [Pb/Fe] to date First Bi to be measured in a metal-poor star

12. (Ivans et al. submitted)

13. In Summary o CS29497-030: first abundance measurement of Bi in a metal-poor star o Bi/Pb in accord with s-process predictions o overall abundance pattern fits that of (r+s) process where s-processing includes r-process pre-enrichment o abundance of Na (and other elements sensitive to the neutron-excess) can be employed to constrain the mass of the AGB progenitor: lower mass stars go through fewer thermal, producing lower abundances of elements sensitive to the neutron excess