Mr. Pearl Earth Science NAME

Mr. Pearl – Earth Science NAME: WPHS Date:

There is a relationship between the temperatures of stars and how bright they are (luminosity). In general, the hotter a star the brighter. This is not always true though. For example, Polaris is the same temperature as our Sun, but is around 4000X brighter. This difference is due to the mass and size of Polaris. All stars fuse Hydrogen into Helium, when enough Hydrogen collects in a “dust” cloud called a nebula. Nuclear Fusion rips the star apart as energy streams into space. At the same time, gravity of the huge star keeps it together. During the star's life, the tug-of-war continues until the Hydrogen runs out. What happens next, depends upon the star’s initial size and mass.

This process is known as stellar evolution, and is described on the chart in Page 15 of the ESRT.

1. According to the diagram, a star like Earth’s Sun will eventually (1) explode in a supernova (2) become a black hole (3) change to a white dwarf (4) become a neutron star

2. Stars like Earth’s Sun most likely formed directly from a (1) nebula (2) supernova (3) red giant (4) black dwarf

3. According to the diagram, the life-cycle path followed by a star is determined by the star’s initial (1) mass and size (2) temperature and origin (3) luminosity and color (4) luminosity and structure

4. The electromagnetic energy that stars radiate is created by the

(1) burning of atoms (3) convection currents within the inner core (2) fusion of Hydrogen (4) difference between massive black holes and their supernovae

5. Starlight provides evidence for the expansion of the universe, due to the fact that wavelengths of light

(1) Stretch (shift red) as distant objects move away (3) Stretch (shift blue) as distant objects move away (2) Shrink (shift red) as distant objects move away (4) Shrink (shift blue) as distant objects move away 6. Fill in the missing parts (A - F) of the luminosity chart from Page 15 of the ESRT. 7. What is the general

relationship in the "Main Sequence" between temperature and luminosity? ______

______

8. What is the approximate temperature of Spica? ______

9. What is the temperature and luminosity of Eridani B? ______

10. Which star is as hot as our sun, but about 4,000 times brighter? ______

11. What is the temperature & color of the giant star Aldebaran? ______

12. What is the average temperature of a main sequence star with a luminosity of 0.1? ______

13. The blue/white star Vega has a surface temperature of about 11,000 K and a luminosity of 80. On the chart above place a star symbol and label for the approximate location of the star Vega.

14. What is one similarity and one difference between the stars Rigel & Betelgeuse? ______