Universe: Stars And Galaxies
6th Edition
ISBN: 9781319115098
Author: Roger Freedman, Robert Geller, William J. Kaufmann
Publisher: W. H. Freeman
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Chapter 22, Problem 26Q
To determine
(a)
The orbital period of the cloud.
To determine
(b)
The mass of the galaxy contained within the cloud’s orbit.
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The Tully-Fischer method relies on being able to relate the mass of a galaxy to its rotation velocity. Stars in the outer-most regions of the Milky Way galaxy, located at a distance of 50 kpc from the galactic centre, are observed to orbit at a speed vrot = 250 km s−1. Using Kepler’s 3rd Law, determine the mass in the Milky Way that lies interior to 50 kpc. Express your answer in units of the Solar mass.
You observe a star orbiting in the outer parts of a galaxy. The distance to this galaxy is known, and
you are able to take a spectra of this star and determine its velocity. The star is 19 kpc from the
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units of solar masses [e.g., 4.2e10].
[Hint: there is a Box in Chapter 22 of your textbook that will be of help. See also the course formula
sheet.]
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Chapter 22 Solutions
Universe: Stars And Galaxies
Ch. 22 - Prob. 1QCh. 22 - Prob. 2QCh. 22 - Prob. 3QCh. 22 - Prob. 4QCh. 22 - Prob. 5QCh. 22 - Prob. 6QCh. 22 - Prob. 7QCh. 22 - Prob. 8QCh. 22 - Prob. 9QCh. 22 - Prob. 10Q
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