maya astro 2 - Chapter 10: The Death of Stars For stars...

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Chapter 10: The Death of Stars For stars with 0.4Msun < M < 8Msun: Main-sequence core H fusion Giant Branch shell H fusion Horizontal Branch core He, shell H fusion Asymptotic Giant Branch shell He, shell H fusion asymptotic giant branch star – a red giant star that has completed core He fusion, now has shell He fusion and has re-expanded - 1 Msun AGB star has a radius of 1 AU (size of Earth’s orbit) - 8 Msun AGB star has a radius of 1.5 AU (size of Mars’s orbit) All giant stars lose mass, and AGB stars lose lots of mass. - He shell flash = runaway He shell fusion that stops and stars several times; each flash causes more of the star’s outer layers to be lost planetary nebula – luminous shell of gas ejected from an old, low-mass star - H, C, Ne, Mg, O, and N have all been observed in planetary nebulae. - After 50,000 years, a planetary nebula will dissipate. - Nebula becomes part of ISM (interstellar medium) again, but some of the gas has been processed into metals. white dwarf – the leftover core of an old, low-mass star; supported by electron degeneracy pressure (no fusion) - mostly C and O, with very thin outside layers of He and H - temperature is too low for fusion, has collapsed down to degenerate matter - spends the rest of eternity radiating away its heat - very small, faint and dense - one teaspoonful of white dwarf matter would weight 5 tons on Earth nova – star that suddenly brightens by a factor of 10^4 – 10^6 (plural: novae) - Novae brighten very quickly and fade slowly - occur in close binary systems where one star is a white dwarf, and the
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This note was uploaded on 03/29/2011 for the course ASTR 1101 taught by Professor Mcgimsey during the Spring '11 term at Georgia State University, Atlanta.

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maya astro 2 - Chapter 10: The Death of Stars For stars...

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