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  • Slide 1
  • Exploding stars And the modeling of Dwarf galaxies http://www.spacetoday.org/images/DeepSpace/Stars/StarWR124Hubble.jpg
  • Slide 2
  • Dwarf Galaxies What are they? Where are they? Why are we interested in them?
  • Slide 3
  • Dwarf galaxy http://upload.wikimedia.org/wikipedia/en/a/a7/Phoenix_Dwarf.jpg Ultra Faint DG
  • Slide 4
  • Dwarf Galaxies What are they? Where are they? Why are we interested in them?
  • Slide 5
  • http://www.sciencecentric.com/images/news/map_milky_way_1000_1000.jpg
  • Slide 6
  • Dwarf Galaxies What are they? Where are they? Why are we interested in them?
  • Slide 7
  • Ultra Faint DGs Very recent discovery ~2005 Low luminosity and metallicity Extreme dark:baryonic 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
  • Slide 8
  • Modeling Supernova SN 1987A: NASA, ESA, P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)
  • Slide 9
  • 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) M Salpeter Initial Mass Function
  • Slide 10
  • Slide 11
  • Slide 12
  • 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
  • Slide 13
  • Slide 14
  • 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
  • Slide 15
  • 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_milky_way_1000_1000.jpg http://www.spacetoday.org/images/DeepSpace/Stars/StarWR124Hubble.jpg
  • Slide 16
  • Mixing Effects Mixing effects for B=1.2 Yield
  • Slide 17
  • Current Supernova Models Simulations are missing ~10 51 ergs! (erg=1 107 joules) To compensate for this missing energy: thermal explosion piston enhanced neutrino opacity Mixing in the star
  • Slide 18
  • Slide 19
  • Slide 20
  • Data sets Mean Yields Subroutine Galactic Model Whole bunch of reading
  • Slide 21
  • Ultra Faint DGs Very recent discovery ~2005 Low luminosity and metallicity Extreme dark:baryonic 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

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