Definitions
Low Mass star: 0.08MSun to 2MSun
Intermediate Mass star: 2 to 8MSun
High Mass star: > 8MSun
Brown dwarfs: Lower than 0.08MSun H-R Diagram
In-class question: Are brown dwarfs really stars? Why, or why not?
The guts (i.e. interiors) of Main Sequence stars: diagram
Hydrogen fusion 4H -> He
lifetime proportional to 1/M2.5
Tale of the Sun's life (incl. future)
After star runs out of helium in core:
Low Mass Stars become giants and supergiants
Hydrogen shell burning helium flash
Evolutionary track H-R diagram of an old cluster
Mass loss and thermal pulses
Planetary Nebulae - The quiet way to die
A large beautiful variety the Ring Nebula the Eskimo Nebula the Spirograph Nebula the Hourglass Nebula more
Intermediate and High Mass Stars H-R Diagram (again)
H fusion is different (but with the same result)
Intermediate – no He flash just 3He -> C burning
Then PN and wd
High mass can burn C
Heavier elements in the core
Intermediate mass stars cannot burn C and so die like low mass stars
High Mass stars' Evolution on H-R Diagram
The trouble with iron – no energy profit
But the core does it anyway!
Star explodes and recycles heavier elements
Supernovae
Where does the energy go?
Light
Ejection velocity
Construction of new elements
The neutron star or black hole magnetic field, spin, heat
If white dwarfs are < 1.4 MSun but started out as large as 8MSun and
Neutron stars are < 3 MSun but started out 10 20MSun
What happened?
Just when you thought you had it all figured out…..
The binary star Algol = 3.7MSun
m-s dwarf and a .8MSun subgiant
Supplemental Material
During Sun's lifetime: Luminosity Radius
