1. LIFE CYCLE OF A STAR Sun (main sequence star) Stellar Nebula
Red Giant
Planetary Nebula
White Dwarf
Shrinks
Few thousand
miles in diameter
No nuclear reactions
Stellar Nebula
(nursery)
Nuclear decreases
Core contracts
Outer layers expand
Outer layers drift to outer space
Outer layers lost to nebula
Longest period of a star’s life
Red Supergiant
Supernova
Massive Star ( Huge)
Massive Star (Giant)
Protostar
Neutron Star
Core collapses instantly
Massive short-lived explosion
Outer layers blown away
Shrinks to small dense star
Very strong gravity
Nuclear decreases
Core contracts
Outer layers expand
Longest period of a star’s life
LIFE CYCLE OF A STAR
Black Hole
Very strong gravity that light can’t escape

2. LIFE CYCLE OF A STAR ON HR DIAGRAM

3. CHECK FOR UNDERSTANDING

4. Which of the following is the correct sequence for the life cycle of our sun?
Protostar Giant Star White Dwarf
Nebula Protostar Supergiant Supernova Black hole
Nebula Protostar Main Sequence White Dwarf

5. If all stars were to be the same size of the sun then which of the following statements is true?
Brighter stars will have lower surface temperatures
Brighter stars will have higher surface temperatures
Luminosity has no relationship to temperature

6. Along which line would you expect to find main sequence stars of the same size?
10r line
r line
.1r line

7. Which of the following conclusions can be drawn from the graph?
The hottest main sequence stars are much larger than the sun.
The hottest main sequence stars are much smaller than the sun
None of the above.

8. Based on the conclusions from the previous two questions which of the following is true?
For all stars of the same size, brighter stars will have a lower surface temperature.
For all stars of the same size, brighter stars will have a higher surface temperature.
None of the above.

9. The surface temperature and luminosity of a star change drastically over the course of a stars life time.
True
False

10. Smaller mass stars have greater luminosity than larger mass stars.
True
False

11. A star with a large mass will radiate more energy into space and appear hotter and brighter than a star with a smaller mass.
True
False