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Study of the sprocess in low mass stars of Galactic disc metallicity

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S-process nucleosynthesis in AGB stars at solar metallicity. ... ls(Sr, Y, Zr) hs(Ba, La, Cs, Nd,Sm) Pb. 9. IRAS 0713 1005. 10. Extrinsic AGBs. 2. 1. 1. 2 ... – PowerPoint PPT presentation

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Title: Study of the sprocess in low mass stars of Galactic disc metallicity


1
Study of the s-process in low mass stars of
Galactic disc metallicity
  • Laura Husti
  • Roberto Gallino
  • Sara Bisterzo

2
  • Outline
  • Origin of the heavy elements.
  • Stellar Nucleosynthesis and Evolution.
  • S-process nucleosynthesis in AGB stars at
    solar metallicity.
  • Comparison with spectroscopic data of
    intrinsic and extrinsic AGBs

3
(No Transcript)
4
Formation of Heavy Elements
  • Thermonuclear reactions Alt56
  • Neutron captures
  • - slow (s-process)
  • 105-1011 free neutrons/cm3
  • - rapid (r-process)
  • 1022-1025 free neutrons/cm3

5
s-process

6
Stellar evolution of low mass stars
  • Core H burning
  • Core H exhaustion and contraction of the star
  • H-shell ignition ? core contraction envelope
    expansion
  • First dredge-up
  • Core He burning
  • Core He exhaustion contraction of the C-O core
  • Degenerate C-O core alternate burning H and He
    shells He intershell extended convective
    envelope

7
Nucleosynthesis in AGB Stars
  • Neutron sources
  • radiative 13C(a,n)16O
  • convective 22Ne(a,n)25Mg
  • 22Ne formation 14 N(a,?)18F(ß,?)18O(a,?) 22Ne
  • 13C formation 12C(p, ?) 13 N(ß,?) 13C(p, ?) 14 N

Busso, Gallino Wasserburg ARAA 1999
8
Variuos 13C pocket efficiencies, same metallicity
hs(Ba, La, Cs, Nd,Sm)
ls(Sr, Y, Zr)
Pb
9
IRAS 07131005
10
Extrinsic AGBs
11
HD 123585
Allen Barbuy 2006
12
Conclusions
  • comparison between theoretical models and
    spectroscopic observations for the element
    abundances of 30 barium stars and 12 post-AGB
    stars
  • models succesfully reproduce the observational
    data
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