Life and Death of a Star
1. How many stars are there in our galaxy?
400 Billion
2. What is a nebula made up of?
A cloud of dust and gas, mostly hydrogen
3. What happens in a nebula?
Clumps of dust and gas pull together to form stars
4. What is the key component of stars?
Hydrogen
5. What force pulls together stars?
Gravity
6. How big of a cloud of gas forms a star like our Sun?
100x the size of our solar system
7. Are nebulas cold or hot?
cold
8. What is a protostar?
A Baby star
9. What is thermonuclear fusion?
H+H
He + ENERGY
10. What is formed when two Hydrogens atoms are fused together?
Helium (He)
11. What force works against gravity in a star?
Nuclear Fusion
12. Keep in mind Pressure is force over area!
13. What is equilibrium?
Force in (gravity) = Force out (Fusion)
14. What is the main sequence?
Stars in equilibrium, converting H to He
15. What is the relationship between the heat of a star and the color of the star?
Hotter = Blue….Cooler = Red
16. What are some of the characteristics of red dwarf stars?
Red, cooler, smaller, most common
17. What are some of the characteristics of blue main sequence stars?
Blue, hotter, larger
18. What is the connection between mass and the life history of a star?
More massive = shorter life
19. The more mass the higher the fusion rate.
20. How long will our Sun live?
5 billion more years
21. What has to happen to the core so that the Sun can fuse Helium?
The core has to be hotter
22. What makes the core’s temperature increase?
gravity
23. The star spends 90% of its life in the Main Sequence.
24. What is the planetary nebula phenomenon?
Star swells as it heats up then ejects outer layers, donating newly formed elements
to the universe
25. What holds the star up against gravity?
The pressure of electrons
26. Describe the process a star takes from a sun like star to a White Dwarf.
Ejects outer layers, contracts down and slowly cools
27. What can happen to White Dwarf in a bininary or a star system?
One can steal more H from its partner, then EXPLODE
28. Thermo Nuclear Runaway is another term for what more commonly used term?
Supernova (Type 1A)
29. The visible light of a Super Nova is what fraction of the total energy?
1/10,000
30. What does the collapse of the Iron core of a giant star cause?
EXPLOSION, Supernova type 2
31. What do Super Novas do for the overall state of the universe?
They are the source of heavy elements
32. Where do all the elements heavier than iron come from?
Supernova explosions
33. What elements in your body are made in Super Novae?
Ca, Fe, C
34. What happens to the core of an exploded Super Nova?
It is intact and becomes a neutron star
35. What is electron degeneracy pressure?
Electrons repel each other and in small stars gravity is not enough to overcome
this—so the star stays a white dwarf
36. Why do electrons push each other apart?
No two electrons can occupy identical states; like charges repel
37. What are the characteristics of a Neutron star?
Rapid spin, dense, heavy, small
38. Give an example of understanding the density of a Neutron star?
1 tsp = 1 billion tons
39. How did astronomer’s first identify Neutron stars?
A beam of light produced by electrons (lighthouse effect)
40. What object has an infinite density?
A black hole
41. What is a black hole?
Complete collapse of a star
42. What were the first stars like?
Massive—their explosions created the first elements for the universe
43. What stars have the largest collision?
2 orbiting neutron stars
44. What regions in galaxies is there a higher likelihood of a collision? Why?
Globular cluster—or organized motion--crowded
45. What is a blue straggler?
Large blue star in a globular cluster of older stars, the result of a collision
46. What are different objects formed at the end of a star’s life?
Black hole, neutron star, white dwarf
47. What is a brown dwarf?
A failed star, small mass so not enough energy to fuse or shine
Nebula Protostar Main Sequence Star Red Giant Planetary Nebula White Dwarf Black Dwarf