The Cosmic Perspective (9th Edition)
9th Edition
ISBN: 9780134874364
Author: Jeffrey O. Bennett, Megan O. Donahue, Nicholas Schneider, Mark Voit
Publisher: PEARSON
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Chapter 19, Problem 46EAP
To determine
The type of orbit that the stars probably have around the Milky Way.
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Astronomers now think that there is a black hole with more than 4 milliion times the mass of our Sun at the center of our galaxy?
Roughly how large would the event horizon of such a supermassive black hole be?
a. the size of our moon
b. about 4 light years across
c. about 17 times the size of our sun
d. about the size of an atom (so much mass really compresses the event horizon)
e. this question can't be answered without knowing what kind of stars were swallowed by the black hole
1. Consider our Sun - it is in orbit around the center of our Milky Way Galaxy.
The velocity of the Sun in its orbit is about 250 km/s. The distance to the center
of the galaxy is about 9.1 kpc (kiloparsecs). We can use Kepler's third law to
calculate the mass of the galaxy interior to the Sun's orbit. We assume that the
orbit is circular so that the semimajor axis is just the radius of the circular orbit =
9.1 kpc. First we need to calculate the number of AU's in 9.1 kpc. (Note that 1
Крс - 1000 рс - 3260 1t yrs and 1 pc - 206,265 AU.)
%3D
a =r =9.1kpc = (9.1kpc) 1000 pc 206,265AU]
1kpc
AU
Sun
1pc
An astronomer observed the motions of some galaxies. Based on his observations, he made the following statements. Which one of them is most likely to be false? Take Hubble's constant to be 67 km/s/Mpc.
A. A galaxy observed to be moving away from us at a speed of 70 km/s is at a distance of about 1 Mpc from us.
B. A galaxy observed to be moving away from us at a speed of 700 km/s is at a distance of about 10 Mpc from us.
C. A galaxy observed to be moving away from us at a speed of 7000 km/s is at a distance of about 100 Mpc from us.
D. A galaxy observed to be moving away from us at a speed of 70000 km/s is at a distance of about 1 Gpc from us.
Is the answer D? Thank you!
Chapter 19 Solutions
The Cosmic Perspective (9th Edition)
Ch. 19 - Prob. 1VSCCh. 19 - Prob. 2VSCCh. 19 - Prob. 3VSCCh. 19 - Prob. 4VSCCh. 19 - Prob. 5VSCCh. 19 - Prob. 6VSCCh. 19 - Prob. 1EAPCh. 19 - Prob. 2EAPCh. 19 - Prob. 3EAPCh. 19 - Prob. 4EAP
Ch. 19 - Prob. 5EAPCh. 19 - Prob. 6EAPCh. 19 - Prob. 7EAPCh. 19 - Prob. 8EAPCh. 19 - Prob. 9EAPCh. 19 - Prob. 10EAPCh. 19 - Prob. 11EAPCh. 19 - Prob. 12EAPCh. 19 - Prob. 13EAPCh. 19 - Prob. 14EAPCh. 19 - Prob. 15EAPCh. 19 - Prob. 16EAPCh. 19 - Prob. 17EAPCh. 19 - Does It Make Sense? Decitie whether the statement...Ch. 19 - Prob. 19EAPCh. 19 - Prob. 20EAPCh. 19 - Prob. 21EAPCh. 19 - Prob. 22EAPCh. 19 - Prob. 23EAPCh. 19 - Prob. 24EAPCh. 19 - Prob. 25EAPCh. 19 - Prob. 26EAPCh. 19 - Prob. 27EAPCh. 19 - Prob. 28EAPCh. 19 - Prob. 29EAPCh. 19 - Prob. 30EAPCh. 19 - Choose the best answer to each of the following....Ch. 19 - Prob. 32EAPCh. 19 - Prob. 33EAPCh. 19 - Prob. 34EAPCh. 19 - Prob. 35EAPCh. 19 - Prob. 36EAPCh. 19 - Prob. 37EAPCh. 19 - Prob. 39EAPCh. 19 - Prob. 40EAPCh. 19 - Prob. 41EAPCh. 19 - Prob. 42EAPCh. 19 - Prob. 44EAPCh. 19 - Prob. 45EAPCh. 19 - Prob. 46EAPCh. 19 - Prob. 47EAPCh. 19 - Prob. 48EAPCh. 19 - Prob. 49EAPCh. 19 - Prob. 50EAPCh. 19 - Prob. 52EAPCh. 19 - Mass of the Central Black Hole. Suppose you...Ch. 19 - Prob. 54EAPCh. 19 - Prob. 55EAPCh. 19 - Prob. 56EAPCh. 19 - Prob. 57EAPCh. 19 - Prob. 58EAPCh. 19 - The Speed of Supernova Debris. The kinetic energy...
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General Relativity: The Curvature of Spacetime; Author: Professor Dave Explains;https://www.youtube.com/watch?v=R7V3koyL7Mc;License: Standard YouTube License, CC-BY