Problems
Problems

 1 A star has a distance of 40 pc. What is the parallax of the star? 2 A star has a parallax of 0.2 seconds of arc. What is the distance of the star? 3 A star has a parallax of 0.11 seconds of arc. Suppose we received radio signals from creatures on a planet orbiting the star and then immediately sent a radio response to the creatures. How long would it be between the time that the creatures transmitted their signal and the time that they received our signal? 4 Suppose a star has a distance of 50 pc. What would be the parallax of the star if it were measured by creatures living on Pluto? On Mercury? 5 Star A is 4 magnitudes brighter than star B. How does the apparent brightness of star A compare with that of star B? 6 Star A is 7 magnitudes brighter than star B. How does the apparent brightness of star A compare with that of star B? 7 Star A is 16 magnitudes brighter than star B. How does the apparent brightness of star A compare with that of star B? 8 Star A has an apparent magnitude of -1. Star B has an apparent magnitude of 5. How does the apparent brightness of star A compare with that of star B? 9 Star A has an apparent brightness that is 40 times as large as that of star B. What is the difference in the magnitudes of the two stars? 10 Two stars differ by 8 in absolute magnitude. What is the ratio of their luminosities? 11 A star has an absolute magnitude of 12 and a distance of 100 pc. What is the apparent magnitude of the star? 12 At what distance does a star have an apparent magnitude that is 5 magnitudes brighter (smaller) than its absolute magnitude? 13 A star is moving away from the Earth at a speed of 200 km/s. What would be the wavelength of a spectral line that would have a wavelength of 500 nm if the star were at rest? 14 In the laboratory, the wavelength of a spectral line of an atom is 450 nm. The same line in the spectrum of a star has a wavelength of 448 nm. What is the radial velocity of the star? Is the star moving toward or away from the Earth? 15 Suppose two stars obey the mass-luminosity relationship. One star is four times as massive as the other. How do the luminosities of the two stars compare?

Home > Chapter 16 > Problems