Exploding stars

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Exploding stars

• And the modeling of
• Dwarf galaxies

http//www.spacetoday.org/images/DeepSpace/Stars/S
tarWR124Hubble.jpg
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Dwarf Galaxies

• What are they?
• Where are they?
• Why are we interested in them?

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Dwarf galaxy
Ultra Faint DG
http//upload.wikimedia.org/wikipedia/en/a/a7/Phoe
nix_Dwarf.jpg
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Dwarf Galaxies

• What are they?
• Where are they?
• Why are we interested in them?

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http//www.sciencecentric.com/images/news/map_milk
y_way_1000_1000.jpg
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Dwarf Galaxies

• What are they?
• Where are they?
• Why are we interested in them?

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Ultra Faint DGs

• Very recent discovery 2005
• Low luminosity and metallicity
• Extreme darkbaryonic matter ratio
• Remnants of early structures in galaxy formation
• Closely linked to the first stars (pop III)
• Chemical Tagging provides valuable information
  about the nature of these galaxies

Black dots Milky Way stars Blue squares DG
stars Red stars Ultra faint DG stars
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Modeling Supernova
SN 1987A NASA, ESA, P. Challis and R. Kirshner
(Harvard-Smithsonian Center for Astrophysics)
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Calculating mean yields

• Using data from papers by Nomoto et al, Woosley
  et al and Chieffi et al.
• Using sum of all isotopes for each element
• Mean yields where calculated using numerical
  integration of

Linear interpolation of (yield of a particular
element) a M
Salpeter Initial Mass Function
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SN Subroutine

• Part of a larger model of Dwarf Galaxy evolution
• Fortran subroutine to calculate yields of a
  certain element for a specified mass and
  metallicity, based on Nomoto SN/HN yields
• Using bilinear interpolation on the tabulated
  values

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Conclusions

• The stellar models are sensitive to a range of
  variables
• Small changes in explosion energy and metallicity
  influence yields
• Abundances of odd elements are particularly
  influenced by the metallicity of a star
• a metallicity parameter and a HN/SN flag has been
  incorporated into a new stellar yield subroutine
  which will form part of a model of galactic
  chemical evolution

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Acknowledgements and Refernces

• Special thank you Dr. Torgny Karlsson, for the
  time he spent helping me learn some new physics.
• Also thanks to Dick Hunstead for organizing the
  projects.
• References
• Nucleosynthesis Yields of Core-Collapse
  Supernovae and Hypernovae, and Galactic Chemical
  Evolution
• Kenichi Nomoto, Nozomu Tominaga, Hideyuki
  Umeda, Chiaki Kobayashi, Keiichi Maeda,
• Nuclear Physics A (2006)
• NUCLEOSYNTHESIS AND EVOLUTION OF MASSIVE
  METAL-FREE STARS
• Alexander Heger, S. E. Woosley
• ApJ, March 21, 2008
• SN 1987A NASA, ESA, P. Challis and R. Kirshner
  (Harvard-Smithsonian Center for Astrophysics)
• http//www.sciencecentric.com/images/news/map_milk
  y_way_1000_1000.jpg
• http//www.spacetoday.org/images/DeepSpace/Stars/S
  tarWR124Hubble.jpg

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Mixing Effects
Mixing effects for B1.2
Yield
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Current Supernova Models

• Simulations are missing 1051 ergs!
• (erg1 10-7 joules)
• To compensate for this missing energy
• thermal explosion
• piston
• enhanced neutrino opacity
• Mixing in the star

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Whole bunch of reading
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Ultra Faint DGs

• Very recent discovery 2005
• Low luminosity and metallicity
• Extreme darkbaryonic matter ratio
• Closely linked to the first stars (pop III)
• Remnants of early structures in galaxy formation
• Chemical Tagging provides valuable information
  about the nature of these galaxies

Black dots Milky Way stars Blue squares DG
stars Red squares Ultra faint DG stars