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7 - Star Death

7 - Star Death. Present-day Abundances of the Elements on the Visible Surface of the Sun. How did this come to be??. Stellar Spectra. THE H ERTZSPRUNG- R USSELL DIAGRAM. Plot of Luminosity (Watts) versus Surface Temperature (Kelvins) ~ 90% lie along Main Sequence.

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7 - Star Death

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  1. 7 - Star Death

  2. Present-day Abundances of the Elements on the Visible Surface of the Sun How did this come to be??

  3. Stellar Spectra

  4. THE HERTZSPRUNG-RUSSELL DIAGRAM Plot of Luminosity (Watts) versus Surface Temperature (Kelvins) ~ 90% lie along Main Sequence

  5. Stellar Radii (in units of the Sun’s Radius)

  6. Pre-Main Sequence Evolution evolutionary tracks - each for a fixed mass at different times isochrones - each for a fixed time and different masses

  7. CNO cycle proton-proton chain

  8. Main Sequence Lifetimes

  9. Post-Main Sequence Evolution: 1 solar mass star

  10. The Sun at Age ~ 10 billion years (note size!!) A little more to proper scale: NOTE: inside the star, C and O (and He) have been built up at the expense of H NOTE: in more massive stars, N has also been built up at the expense of H

  11. Outer layers lost to space as planetary nebulae (have nothing to do with planets, though..) Net enrichment of galaxy in CNO

  12. Leftover core becomes a White Dwarf Star A million times denser than water - a spoonful would weigh a TON on Earth!

  13. High Mass Stars & Supernovae - (SN II) C-burning O-burning Ne-burning Massive stars also build up Na, Mg, Ne, S, P, and Si…

  14. “Si-burning” …and Ar, Ti, Cr,Fe, Ni, etc…

  15. “Si-burning” Supernova explosion returns these elements back into space……

  16. “Veil Nebula” Tycho’s SN (X-rays - Chandra) Core collapses due to pressure winning over gravity - leading to Supernova Type II explosion & return of heavy elements to galaxy….. Cygnus Loop Supernova Remnants Crab Nebula (visible light - VLT) Kepler’s SN (X-rays - Chandra)

  17. If matter “accretes” onto WD, can get explosive nucleosynthesis - “nova” If mass of WD grows to 1.4 Msun - Type Ia Supernova SN Ia erupts in a galaxy Again, these return material to galaxy enriched in “heavies”

  18. just after 3 min Inherited by Pop III just after big bang Buildup of heavies with time After Pop II Inherited by Pop I (Sun) After Pop III Inherited by Pop II

  19. The history of the Universe has been one of Gradual Increase in the Abundances of the Heavier Elements Required by Life on the Earth (and presumably elsewhere) TIME

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