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 24, Problem 9Q
To determine
The time in the past to which the person is looking if he or she observes a quasar with a redshift
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Students have asked these similar questions
If a galaxy is 9.0 Mpc away from Earth and recedes at 488 km/s, what is H0 (in km/s/Mpc)?
km/s/Mpc
What is the Hubble time (in yr)?
years
How old (in yr) would the universe be, assuming space-time is flat and the expansion of the universe has not been accelerating?
How would acceleration change your answer?
A.If the expansion of the Universe has been accelerating, the Universe could be substantially younger than the value entered above.
BIf the expansion of the Universe has been accelerating, the Universe could be substantially older than the value entered above.
If a galaxy is 8.9 Mpc away from Earth and recedes at 497 km/s, what is H. (in km/s/Mpc)?
km/s/Mрс
What is the Hubble time (in yr)?
years
How old (in yr) would the universe be, assuming space-time is flat and the expansion of the universe has not been accelerating?
years
How would acceleration change your answer?
If the expansion of the Universe has been accelerating, the Universe could be substantially younger than the value entered above.
If the expansion of the Universe has been accelerating, the Universe could be substantially older than the value entered above.
3C 273 was the first quasar identified (1963). When we look at its chemical spectrum, we see that its hydrogen alpha emission line (Hα) has an observed wavelength of λobs = 759 nm.-(By comparing the observed wavelength of Hα with the rest-frame (source) wavelength, find 3C 273’s redshift, z.- How fast is 3C 273 moving away from us in km/s?-Assuming the value of Hubble constant listed in the table at the top of the page, how far away is 3C 273 in Mpc? This was, at the time, the most distant object in the known universe!answer to three significant figures
Chapter 24 Solutions
Universe: Stars And Galaxies
Ch. 24 - Prob. 1QCh. 24 - Prob. 2QCh. 24 - Prob. 3QCh. 24 - Prob. 4QCh. 24 - Prob. 5QCh. 24 - Prob. 6QCh. 24 - Prob. 7QCh. 24 - Prob. 8QCh. 24 - Prob. 9QCh. 24 - Prob. 10Q
Ch. 24 - Prob. 11QCh. 24 - Prob. 12QCh. 24 - Prob. 13QCh. 24 - Prob. 14QCh. 24 - Prob. 15QCh. 24 - Prob. 16QCh. 24 - Prob. 17QCh. 24 - Prob. 18QCh. 24 - Prob. 19QCh. 24 - Prob. 20QCh. 24 - Prob. 21QCh. 24 - Prob. 22QCh. 24 - Prob. 23QCh. 24 - Prob. 24QCh. 24 - Prob. 25QCh. 24 - Prob. 26QCh. 24 - Prob. 27QCh. 24 - Prob. 28QCh. 24 - Prob. 29QCh. 24 - Prob. 30QCh. 24 - Prob. 31QCh. 24 - Prob. 32Q
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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
- If a galaxy is 9.0 Mpc away from Earth and recedes at 488 km/s, what is H, (in km/s/Mpc)? | km/s/Mpc What is the Hubble time (in yr)? | years How old (in yr) would the universe be, assuming space-time is flat and the expansion of the universe has not been accelerating? years How would acceleration change your answer? O If the expansion of the Universe has been accelerating, the Universe could be substantially younger than the value entered above. O If the expansion of the Universe has been accelerating, the Universe could be substantially older than the value entered above. Need Help? Read Itarrow_forwardUsing our example from the previous unit, let's try to determine the Hubble time for this example universe. You were given that a good representative galaxy receded at a speed of 4000 km/s and was found to be 20 Mpc away. With that in mind, what would the age of that universe be in years (aka what is that universe's Hubble time)? Go ahead and take the number of kilometers per Mpc to be approximately 3.1*10^19 km/Mpc. While this problem may look scary at first, this is really just bringing you full circle to one of the unit conversion problems you encountered at the beginning of this course.arrow_forwardWhat evidence is there that quasars occur in distant galaxies? Explain.arrow_forward
- Recall that Hubbleʹs law is written v = H0d, where v is the recession velocity of a galaxy located a distance d away from us, and H0 is Hubbleʹs constant. Suppose H0 = 80 km/s/Mpc. How fast would a galaxy located 800 megaparsecs distant be receding from us? A. 64 Mpc/s B. 64,000 km/s C. 0.1 times the speed of light D. 10 km/s E. 64 km/sarrow_forwardSuppose a universe is spatially flat, and (at some moment in time) has density ρ. Suppose a creature living in one galaxy in this universe sees a second galaxy receding (at this same moment in time), with its spectral lines redshifted by a factor of z. How far away is the second galaxy from the first? (Note the distance is small enough that Hubble's law can be safely applied.) Values: ρ = 5x10-27 kg m-3 z = 0.10 Enter your answer in Mpc, rounded to the nearest integer.arrow_forwardIf a galaxy is 500 Mly away from us, how fast do we expect it to be moving and in what direction?arrow_forward
- Explain briefly the main physical processes that occurred in the era of recombination. If the recombination era took place at a redshift (1 + z) = 1100, calculate the temperature of the Universe at the era of recombination considering that the Cosmic Microwave Background (CMB) is a perfect black body and today has a temperature T = 2.725 K. State the peak wavelength at which the Universe emitted its radiation during the era of recombination, expressing your answer in nm.arrow_forwardThe Andromeda Galaxy is a member of the Local Group of galaxies. It is approaching us. Does this mean that the Hubble Law is wrong? Why or why not? Explain.arrow_forwardAn 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!arrow_forward
- If a galaxy is 8.8 Mpc away from Earth and recedes at 498 km/s, what is H0 (in km/s/Mpc)? _______ km/s/Mpc What is the Hubble time (in yr)? _______ yr How would acceleration change your answer? A: If the expansion of the Universe has been accelerating, the Universe could be substantially younger than the value entered above. B: If the expansion of the Universe has been accelerating, the Universe could be substantially older than the value entered above.arrow_forwardWhat evidence do we have that the luminous central region of a quasar is small and compact?arrow_forwardRapid variability in quasars indicates that the region in which the energy is generated must be small. You can show why this is true. Suppose, for example, that the region in which the energy is generated is a transparent sphere 1 light-year in diameter. Suppose that in 1 s this region brightens by a factor of 10 and remains bright for two years, after which it returns to its original luminosity. Draw its light curve (a graph of its brightness over time) as viewed from Earth.arrow_forward
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