Last Time: A Glimpse at Stellar Evolution

• observed HR diagram: young open clusters, old globular clusters
• spoiler: HR diagram animations here and here

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A Theory of Stars

Towards a Theory of Stars

• the goal: use physics to peer inside stars
• ingredients of a stellar model
• challenges in real stars:
  • mass loss
  • rotation here, here, and here,
  • magnetic fields: solar magnetogram real time image and movie
  • binarity
• basic stellar models: simplifying assumptions
• enclosed mass coordinate

Stellar Gravitation

• Gauss' law
• a gravitating sphere