Based on the definition of apparent brightness, which units are appropriate for its measurement?
A) watts
B) joules
C) watts per square meter
D) Newtons
Answer: C
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Astronomy Chapter 15
- The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is most likely to be located in the halo of our galaxy?
- The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest?
- How did astronomers discover the relationship between spectral type and mass for main-sequence stars?
- The approximate main-sequence lifetime of a star of spectral type O is
- You observe a star and you want to plot it on an H-R diagram. You will need to measure all of the following, except the star's
- Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 73 hours the star becomes dimmer for about 2 hours. The most likely explanation is that
- To calculate the masses of stars in a binary system, we must measure their
- Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude?
- Which of the following statements about spectral types of stars is not generally true?
- The star Vega has an absolute magnitude of about 4 and an apparent magnitude of about 0. Based on the definitions of absolute and apparent magnitude, we can conclude that
- A star with a parallax angle of 1/20 arcsecond is
- Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore
- All stars are born with the same basic composition, yet stars can look quite different from one another. Which two factors primarily determine the characteristics of a star?
- What do we mean by the main-sequence turnoff point of a star cluster, and what does it tell us?
- Which of the following statements comparing open and globular star clusters is not true?
- What is a white dwarf?
- Suppose our Sun were suddenly replaced by a supergiant star. Which of the following would be true?
- What is the common trait of all main-sequence stars?
- Each choice below lists a spectral type and luminosity class for a star. Which one is a red supergiant?
- How is the lifetime of a star related to its mass?
- On an H-R diagram, stellar masses
- On an H-R diagram, stellar masses
- On an H-R diagram, stellar radii
- The axes on a Hertzsprung-Russell (H-R) diagram represent