Decoding the H-R Diagram: Star Clusters

• open clusters Plieades, Hyades, Praesepe/Beehive
• globular clusters: 47 Tuc, M15
• Gaia DR2 HR diagrams:
  • open clusters: Hyades and Praesepe, 32 clusters
  • globular clusters: 47 Tuc, 14 clusters
  • 4.2+ million stars
• implications of stellar evolution: elliptical galaxies small and large

A Theory of Stars

Towards a Theory of 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