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 23, Problem 34Q
To determine
The measurementsthat astronomers make to construct three-dimensional maps of the positions of galaxies in space.
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Students have asked these similar questions
An observational survey of distant galaxies is undertaken that involves measuring their
distances using cepheid variables and red-shifts using spectroscopy. Explain how cepheid
variables can be used to measure the distances to galaxies.
A spectral line is observed whose wavelength in the laboratory is de
length of this spectral line observed in each galaxy, Xo, is listed in the table, along with
the distance, d, to the galaxy. Determine the red-shift and the recession velocity of each
galaxy and tabulate your results by making a copy of the table and filling in the blank spaces.
Sketch a Hubble diagram using your results and determine the value of the Hubble constant
Ho in units of km s-1 Mpc.
650 nm. The wave-
Galaxy 1
652.69
Galaxy 2 Galaxy 3 Galaxy 4 Galaxy 5
653.01
do (nm)
d (Mpc)
658.54
662.18
681.63
17
19
54
77
200
v (km s-1)
A star at a distance of 50000 light years from the center of a galaxy has an orbital speed of 100 km/s around the galactic center. What is the total mass of the galaxy located at distances smaller than 50000 light years from the center?
A. 7.6 ×1010 solar masses
B. 4.2 ×1011 solar masses
C. 3.5 ×1010 solar masses
D. 1.4 ×1011 solar masses
Is the answer C?
M = (r x v^2) / G
= 50000 x 9.46e15 x (100000^2) / 6.67e-11 / 2e30 (the Sun's mass)
= 3.55e10 solar masses
what is the difference between an E0 galaxy and an E1 galaxy?
Chapter 23 Solutions
Universe: Stars And Galaxies
Ch. 23 - Prob. 1QCh. 23 - Prob. 2QCh. 23 - Prob. 3QCh. 23 - Prob. 4QCh. 23 - Prob. 5QCh. 23 - Prob. 6QCh. 23 - Prob. 7QCh. 23 - Prob. 8QCh. 23 - Prob. 9QCh. 23 - Prob. 10Q
Ch. 23 - Prob. 11QCh. 23 - Prob. 12QCh. 23 - Prob. 13QCh. 23 - Prob. 14QCh. 23 - Prob. 15QCh. 23 - Prob. 16QCh. 23 - Prob. 17QCh. 23 - Prob. 18QCh. 23 - Prob. 19QCh. 23 - Prob. 20QCh. 23 - Prob. 21QCh. 23 - Prob. 22QCh. 23 - Prob. 23QCh. 23 - Prob. 24QCh. 23 - Prob. 25QCh. 23 - Prob. 26QCh. 23 - Prob. 27QCh. 23 - Prob. 28QCh. 23 - Prob. 29QCh. 23 - Prob. 30QCh. 23 - Prob. 31QCh. 23 - Prob. 32QCh. 23 - Prob. 33QCh. 23 - Prob. 34QCh. 23 - Prob. 35QCh. 23 - Prob. 36QCh. 23 - Prob. 37QCh. 23 - Prob. 38QCh. 23 - Prob. 39QCh. 23 - Prob. 40QCh. 23 - Prob. 41QCh. 23 - Prob. 42QCh. 23 - Prob. 43QCh. 23 - Prob. 44QCh. 23 - Prob. 45QCh. 23 - Prob. 46QCh. 23 - Prob. 47QCh. 23 - Prob. 48QCh. 23 - Prob. 49QCh. 23 - Prob. 50QCh. 23 - Prob. 51QCh. 23 - Prob. 52QCh. 23 - Prob. 53QCh. 23 - Prob. 54QCh. 23 - Prob. 55QCh. 23 - Prob. 56QCh. 23 - Prob. 57Q
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- Assume that the Sun orbits the center of the Galaxy at a speed of 220 km/s and a distance of 26,000 lightyears from the center. A. Calculate the circumference of the Sun’s orbit, assuming it to be approximately circular. (Remember that the circumference of a circle is given by 2pR, where R is the radius of the circle. Be sure to use consistent units. The conversion from light-years to km/s can be found in an online calculator or appendix, or you can calculate it for yourself: the speed of light is 300,000 km/s, and you can determine the number of seconds in a year.) B. Calculate the Sun’s period, the “galactic year.” Again, be careful with the units. Does it agree with the number we gave above?arrow_forwardHow many galaxies like our own would it take if they were placed edge-to-edge to reach the nearest galaxy? (Hint: See Problems 11 and 12.)arrow_forwardOne way to calculate the size and shape of the Galaxy is to estimate the distances to faint stars just from their observed apparent brightnesses and to note the distance at which stars are no longer observable. The first astronomers to try this experiment did not know that starlight is dimmed by interstellar dust. Their estimates of the size of the Galaxy were much too small. Explain why.arrow_forward
- The first clue that the Galaxy contains a lot of dark matter was the observation that the orbital velocities of stars did not decreases with increasing distance from the center of the Galaxy. Construct a rotation curve for the solar system by using the orbital velocities of the planets, which can be found in Appendix F. How does this curve differ from the rotation curve for the Galaxy? What does it tell you about where most of the mass in the solar system is concentrated?arrow_forwardWhen comparing two isolated spiral galaxies that have the same apparent brightness, but rotate at different rates, what can you say about their relative luminosity?arrow_forwardThe dwarf galaxy in Sagittarius is the one closest to the Milky Way, yet it was discovered only in 1994. Can you think of a reason it was not discovered earlier? (Hint: Think about what else is in its constellation.)arrow_forward
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