Post on 20-Nov-2014
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DESCRIPTIONMy lecture on the history of cosmology, how our understanding of the universe we live in improved in the 20th century and the great debate.
- 1. ISLAND UNIVERSES
2. The Great Debate What if one walk to the end of the world? 3. 905: Sufi (small cloud) 4. 18th Charles Messier: Catalogs of nebulous objects 5. 1758: Hershel: Andromeda is the nearest great nebulae. 6. 1845 Lord Ross: Elliptical, spiral nebulae 7. 1864: William Huggins Spectrum of Andromeda is similar to stars (continuous and superimposed by dark lines) 8. 1885 Supernova S-AndromedaType Ia 9. Type I Supernovae Binary system One is greater in mass AGB: Rapid mass loss -> angular momentum White dwarf attracts the mass of the companion Mass loss -> Orbit period: hours! 10. Nova Roche Lobe Astronaut orbiting space shuttle Hill Sphere The largest sphere, centered at the second body, within which the sum of the three fields is always directed towards the second body. A small third body can orbit the second within the Hill sphere. 11. Nova Accretion Fusion of H and He Nova is a variable star RS-Oph 12. Type I Supernovae WD reaches Chandrasekhar limit The limit is never attained Increase of pressure -> T near core Convection for 1000 years Carbon fusion (unknown) Oxygen fusion 13. Fusion -> Raises T A MS star expands but WD has degeneracy pressure The story of cold plasma, Pauli, Heisenberg P = Kn5 / 3 instead of PV = NkT T has minor effect on pressure -> Nothing to stop T raising Instability 14. Instability 15. Thermonuclear explosion 1046 j -> Unbind the star Abs. Mag. = -19.3! Type I supernovae are found all around the world, elliptical glx, GCs, etc. And S-And. Standard Castle 16. SN Type Ia. It takes months for SN to dim 17. The Great Debate April 26 1920 On The Scale of The UniverseHarlow ShapleyHeber Curtis 18. The Great Debate Harlow Shapley Heber Curtis Milky Way is the entire Andromeda has more universenovae than observed in Andromedas observedthe entire sky rotating (speed of SN S-And light) Island Universes 19. Andromeda (M31) Galaxy 20. Milky Way 21. Celestial Coordinate Systems 22. Equatorial Coordinates 23. Shapleys GCs Method 24. Galactic Coordinates