Lecture 16 - Stellar Evolution (3/16/99)

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ASTR012 Reading:
Chapter 16-3, 16-5, Prelude P-5 (ZG4)

pages 61-68

M57, the Ring Nebula, in the consellation Lyra. This is an example of a planetary nebula, the ejected envelope of the post-main-sequence white dwarf remnant at the center of the ring. (Courtesy SEDS)
? Key Question: What determines the path of a star on the H-R diagram?
! Key Principle: The uncertainty principle and degeneracy
# Key Problem: Follow the life-cycle of a solar-mass star


  1. Main Sequence Revisited
  2. Degeneracy
  3. Post-Main Sequence Evolution
  4. Late Stages of Stellar Evolution
  5. Massive Stars

Stellar Remnants: Planetary Nebulae

The Ring Nebula M57, courtesy HST/STSCI

Planetary nebulae are the outer layers of a star, blown away during the thermal pulsing of the helium shell-burning phase of its evolution. The Hubble Space telescope has snagged a number of spectacular images of planetary nebulae, showing the variety of rings blown by these dying stars.

Mass loss is a general phenomenon, with both AGB stars and hot main sequence stars losing significant amounts of their envelopes during various stages in their lives.

Some examples:

Stellar Evolution in Outline:

  1. The Life Cycles of Stars
  2. The Tale of the Core
  3. Low Mass Stars
  4. Medium Mass Stars
  5. Degenerate Matter
  6. Planetary Nebulae
  7. White Dwarfs

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smyers@nrao.edu Steven T. Myers