Name ______Period ______
Stars and Life Cycle of Stars Study Guide
1. Luminosity – brightness of a star
2. Absolute magnitude – The measure of how bright a star would be at a set distance from Earth, actual brightness of a star
3. Star – a celestial body that is composed of gas and that emits light
4. Apparent magnitude – the brightness as seen from Earth
5. Binary star system– two stars revolving around each other
6. Multiple star systems – more than two stars revolving around each other
7. H-R diagram – a diagram that compares absolute magnitude to color/temperature of stars
8. Nebula – a large cloud of dust and gas in a region where stars are born
9. Neutron star – a star that collapsed under gravity to the point where electrons and protons have smashed together to form neutrons
10. White dwarf – a small, hot, dim star that is the leftover center (core) of an old low-mass star
11. Main sequence – the location on the H-R diagram where most of the stars lie
12. Supernova – a giant explosion in which massive stars collapse and throw its outer layers into space
13. Black hole –the end of a high-mass star sometimes leaves behind an invisible object in which gravity is so strong
radiation cannot escape
14. Organize the colors/temperatures of stars from coolest to hottest.
Red, orange, yellow, white, blue
15. What solar radius do astronomers give the sun when measuring relative star size? 1
16. Why is the absolute magnitude of some stars greater than their apparent magnitude?
If the star is far away we will not see a bright star from Earth
17. The lower the number the ______(brighter or dimmer) the star.
18. List the sizes of stars from the smallest to the largest.
Neutron star, white dwarf, medium, giant, supergiant
Use the H-R diagram on pgs. 34 and 35 to answer questions 19-31
19. Which of the following stars have the greatest luminosity?
Procyon Betelgeuse Proxima Centauri Sirius Bellatrix
20. Which of the following stars are the hottest?
Procyon Betelgeuse Proxima Centauri Sirius Bellatrix
21. Which star on the H-R diagram is cool and dim? Proxima Centauri or red dwarfs
22. Which star on the H-R diagram is hot and bright? Bellatarix
23. Which group of stars is hot and dim? White dwarfs
24. What brightness and temperature is our sun? medium brightness, medium temperature
25. True or False Absolute magnitude is not related to the color of a star.
26. True or False Blue stars are farther from Earth than red stars.
27. True or False Blue stars are generally more luminous than red stars.
28. True or False Hot stars are located on the right side of the diagram.
29. True or False Bright stars are located at the top of the diagram.
30. True or False Dim stars are found on the left of the diagram.
31. True or False Cool stars are found on the left of the diagram.
32. How do astronomers measure the brightness of stars?
By its luminosity and magnitude
33. What source of energy occurs throughout most of a star’s brightness?
Nuclear fusion
34. Describe our sun’s brightness, color, temperature and if it is a low-mass star or a high-mass star.
Medium brightness, yellow, low-mass
35. Where do all stars form? nebula
36. What determines the life cycle of a star? Its mass
37. List in order the life cycle of a low-mass star starting with nuclear fusion.
Nuclear fusion, red giant, (planetary nebula), white dwarf
38. List in order the life cycles of high-mass stars starting with nuclear fusion.
Nuclear fusion, red supergiant, supernova, neutron star or black hole
39. What part of the H-R diagram do stars spend most of their life in? main sequence
40. What kind of star (low – mass or high mass) becomes a giant star when fusion slows down and the outer atmosphere of the star expands, luminosity increases and helium fuses into carbon and heavier elements?
41. Where does nuclear fusion occur? the core of a star
42. When does nuclear fusion begin? when the temperature of the core is 10,000,00°C or higher
43. What changes within a star that lead to the red giant stage of its life cycle?
Fusion slows down, the outer atmosphere of the star expands, luminosity increases, and the star begins to fuse helium into carbon and heavier elements
44. What causes a supernova? The collapse of the core of a high-mass star