1. Stars

2. Before the first star
Early Universe, Matter is cooling out of white hot plasma due to E=mc2
Finally forms first atoms - Hydrogen
This is 400,000 years after the “Big Bang”

4. Lots of hydrogen create gigantic clouds or nebula in space.
Many are still around.

6. For you Mass Effect Fans

10. Hydrogen, so what?
Nothing but hydrogen clouds makes for a boring universe…
Or does it?
What will all that H do?

11. What happens when you put 1
What happens when you put 1.99X1030 Kg (1,990,000,000,000,000,000,000,000,000,000Kg) of Hydrogen together?
Gravity pulls it together.

12. Just a theory…

13. Finally It takes 399,600,000 years after the first H atoms appear.
A mass of hydrogen atoms reaches critical density and pressure
Ignition!

16. Recipe for a Star
97% hydrogen, 3% helium (and traces of heavier elements) in the form of:
Dust and gas from the Interstellar Medium
Concentrate into a nebula
Add gravity and let it compress!

17. Ignition of what? What do we get from the sun? Light, heat, etc.
Must come from somewhere…
How is it produced???

18. This sucker is nuclear!

19. Yes! Nuclear Fusion!

20. Real Ultimate Energy
Nuclear Fusion produces energy according to Einstein’s equation
E = mc2
Hydrogen is the fuel

21. Find Balance… Hydrogen fusion = the “Main Sequence”
Intense energy production from fusion creates outward pressure.
While immense amounts of gravity pull everything inward!
This state where these intense forces are balanced is called “Equilibrium”

22. How long will it last? Depends on the star
As we can easily tell just by looking up at night, not all stars are the same
A stars lifespan depends on its size and mass.
Why?

23. Rosetta Nebula

24. X-ray image revealing hundreds of young stars in the Rosetta Nebula

25. Composite image of the young stars inside the nebula

27. To Recap
As the gas is clumping together, the star is “gestating” (Like a fetus)
When the clumps in the nebula reach a critical point (high enough density and pressure)
Fusion!
This marks the “birth” of the star.
It begins to emit energy (heat, light, etc.)
A star is born!