Unformatted text preview: 11.26.2007 – Astronomy 13. White dwarf- Carbon/Oxygen core exposed- About ½ mass of sun, 1 earth across- Surface temp around 50,000K when formed, but cools to 10,000 within a few centuries- Much lower luminosity, but very hot 14. Black Dwarf- Temperature approaches 0 K (never actually get there)- Because of electron degeneracy pressure, they don’t shrink Blue stragglers:- Formed by late mergers- Inner 2 parsec: ~ 10 million stars (Sun, 2 pc: 4 stars) Evolution of Stars more massive than the Sun- Evolution proceeds more rapidly because higher temps are achieved more easily- More than 2.5 solar masses: helium burning begins before EDP sets in (no helium flashes)- More than 8 solar masses: helium burning begins before giant stage o Core temp is great enough to burn up to iron o Iron cannot have energy extracted from it o This leads to a supernova Core Collapse Supernovae Type II 20 solar mass star (very rare)- Burns through hydrogen in about 10 million years, helium in 1 million, carbon in 1000, oxygen in 1 year,…...
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- Fall '08
- Astronomy, Supernova, White dwarf, Core temp, iron o Iron, Core Collapse Supernovae