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

LIFE CYCLE OF A STAR ON HR DIAGRAM http://aspire.cosmic-ray.org/labs/star_life/support/HR_animated_real.html

CHECK FOR UNDERSTANDING

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

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

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

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.

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.

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

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

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