1. A star's Life Cycle at a Glance
Star Life Cycle: Stars are like humans. They are born, live and then die.

2. _____________ _____________ is the total mass of the gas and dust between the stars.
Interstellar Medium

3. NEBULA
_____________: A dense cloud of gas and dust

4. The nebula begins to contract due to __________ and the pressure and temperature increase and becomes a ________________.
gravity
PROTOSTAR

5. When the temperature gets hot enough, _______________ begins and a _______ ____________ star is born.
fusion
MAIN SEQUENCE

6. A star loses ____________ during fusion as energy is released
A star loses ____________ during fusion as energy is released. This decreases the star’s gravity. A star will expand, becoming a ___________ ____________, when the outward force of ________________ is greater than the inward force of ______________.
mass
RED GIANT
fusion
gravity
The Suns Expansion to a Red Giant Video

7. fusion
As the fuel runs out in a star, _________ slows down. When the ______________ force of fusion is less than the ____________ force of gravity, the star will shrink in size, becoming a _________ ____________.
outward
inward
WHITE DWARF
White Dwarf
A ____________ is a rotating white dwarf emitting radio waves.
PULSAR

8. SUPERNOVA
explosion
A ___________________ is an _________________ that marks the end of a very massive star’s life. When it occurs, the exploding star can outshine all of the other stars in the galaxy in total for several days and may leave behind only a crushed core.

9. The life cycle of stars depends on their mass.
Small and medium stars become __________________ once they die.
Larger stars become novae and die as: ____________
BLACK DWARVES
NEUTRON STAR
A neutron star is an imploded core of an exploded star made up almost entirely of neutrons. A teaspoon of their material would weigh more than all of automobiles in the U.S. together
The most massive stars become supernovae and die as:
______________________
BLACK HOLE
A black hole is an extremely massive remnant from which light can not escape

10. Life Cycle of a Star Animation

11. gravity quickly quickly lives fusion
Why do larger/hotter stars burn their fuel faster and live shorter lives than the Sun?
Large, more massive stars have much more _____________ than the sun. This greater internal pressure causes fusion reactions to occur __________. This causes the largest stars to burn their fuel, and eventually run out, much more ______________.
Larger stars live shorter _____________.
Bigger stars are brighter and hotter due to the rapid rate of __________.
gravity
quickly
quickly
lives
fusion

12. sun Where do we get the elements??
All stars spend the majority of their lives fusing __________ into ________________: the main sequence.
hydrogen
helium
When all of the __________ in the central regions is converted to helium, the star will begin to “burn” helium into _______________.
hydrogen
carbon
sun
Stars heavier than about 5 times the mass of the ______ can do this with no problem: they burn _____________, and then _______________, and then _____________, _______________, silicon, and so on…until Iron.
hydrogen
helium
carbon
oxygen

13. energy
Iron is the lightest element that doesn’t release __________ when you attempt to fuse it together. You actually end up with less energy than you started with! So instead of generating pressure to hold up the outer layers, the iron fusion actually takes it out of the core. Thus, there is nothing left to combat ________________ from the outer layers. The result: ___________!
gravity
collapse
This implosion (___________) happens very, very quickly: about 15 seconds. During the collapse, the nuclei in the outer parts of the star are pushed together, so close that elements heavier than __________ are formed.
supernova
Iron

14. In truth, where have all of the elements on Earth come from?

15. What determines the life cycle of a star?
Task1: Complete Stellar Evolution activity sorting out life cycles of low vs. high mass stars
Write out the order starting with NEBULA and take 3 paths ending with
1.)Black dwarf, 2.) Neutron Star, 3.) Black Hole
Task 2: On your flow chart, pencil in the relationships between the force of fusion and force of gravity for main sequence, giants, white dwarfs, and supernova’s.
Ff>Fg Ff~Fg Ff < Fg
Task 3: Include information on Luminosity, Temp, and fusion elements where applicable using your guided notes and chart in the lab

16. Video: Life and Death of a Star Complete video Q’s

17. Part II: Understanding the Characteristics of Stars and the H-R diagram

18. Why must be take into account distance if we want to measure the actual magnitude of a star (real brightness)?

19. Measuring Stars Vocabulary:
Absolute Magnitude
Apparent Magnitude VS.
Is how bright a star appears to be
What is the problem with looking at how bright a star APPEARS to be? 
This takes brightness AND distance into account
We measure the brightness of a star at a given distance from us

20. Vocabulary: Luminosity: Our sun’s Luminosity
Is the actual brightness of a star, or rate of total energy emitted compared to our sun in (Units=Watts/second)
Absolute Magnitude-
a stars brightness at a standard distance
= 3.85 x 10^26 Watts/second! (actual)
We compare other stars to the sun which has a luminosity of “1” comparatively
*Note luminosity is logarithmic on an H-R diagram

21. Stars are plotted by Temp, Size/Mass, and Luminosity and on an H-R Diagram

22. Star Size and Color: What does it mean. 1
Star Size and Color: What does it mean? 1.)The colors of stars depend upon its temperatures 2.) LUMINOSITY DEPENDS PRIMARILY ON SIZE! Rule: only with increasing temperature of Main Sequence stars is does luminosity increase

23. How does color represent Temperature?
RedOrangeYellowWhite/YellowWhiteBlue/White
Coolest Hottest!
How does color represent Temperature?

24. Back to the H-R
Why does Betelgeuse, have approximately a temperature of 3,000C and have a luminosity +100,000x that of the sun?

25. Comparing H-R stars 90% of stars are main sequence on the H-R diagram
(Middle of H-R diagram). These are earlymiddle-aged stars
Giants- Are cooler but massive, brighter stars from middle- age to the latter stages of their life.
A supergiant- high mass star near the end of its life but radius is 30500x that of our sun! These are the brightest stars (TOP of H-R)
White Dwarfs are the dying remnant of imploded average star at the very end of it’s life radius = .01x and under that of our sun(BOTTOM of H-R)