exploding stars and the modeling of dwarf galaxies
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Exploding starsAnd the modeling of
Dwarf galaxies
http://www.spacetoday.org/images/DeepSpace/Stars/StarWR124Hubble.jpg
Dwarf GalaxiesWhat are they?
Where are they?
Why are we interested in them?
Dwarf galaxy
http://upload.wikimedia.org/wikipedia/en/a/a7/Phoenix_Dwarf.jpg
Ultra Faint DG
Dwarf GalaxiesWhat are they?
Where are they?
Why are we interested in them?
http://www.sciencecentric.com/images/news/map_milky_way_1000_1000.jpg
Dwarf GalaxiesWhat are they?
Where are they?
Why are we interested in them?
Ultra Faint DG’s
• 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 starsBlue squares: DG starsRed stars: Ultra faint DG stars
Modeling Supernova
SN 1987A: NASA, ESA, P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)
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:
2
1
2
1
35.2
35.2)(
M
M
M
M
element
dmm
dmmmp
yield
Linear interpolation of (yield of a particular element) α M
Salpeter Initial Mass Function
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
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
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
Ken’ichi Nomoto, Nozomu Tominaga, Hideyuki Umeda, Chiaki Kobayashi, Keiichi Maeda,Nuclear Physics A (2006)
• NUCLEOSYNTHESIS AND EVOLUTION OF MASSIVE METAL-FREE STARSAlexander Heger, S. E. WoosleyApJ, 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
Mixing EffectsMixing effects for B=1.2
Yiel
d
Current Supernova Models
• Simulations are missing ~1051 ergs! (erg=1 × 10−7 joules)
• To compensate for this missing energy:– thermal explosion– piston– enhanced neutrino opacity
• Mixing in the star
Whole bunch of reading
Ultra Faint DG’s
• 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 starsBlue squares: DG starsRed squares: Ultra faint DG stars
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