Life in the Universe (4th Edition)
4th Edition
ISBN: 9780134089089
Author: Jeffrey O. Bennett, Seth Shostak
Publisher: PEARSON
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Textbook Question
Chapter 11, Problem 48IF
Stars with Habitable Planets. Based on what you’ve learned about stars in this chapter, make your best estimate of the fraction of all stars around which you’d expect to find planets in habitable zones. Clearly explain how you come up with your estimate, and what uncertainties still need to be addressed.
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Tutorial
A radio broadcast left Earth in 1923. How far in light
years has it traveled?
If there is, on average, 1 star system per 400 cubic light
years, how many star systems has this broadcast
reached?
Assume that the fraction of these star systems that
have planets is 0.50 and that, in a given planetary
system, the average number of planets that have
orbited in the habitable zone for 4 billion years is 0.40.
How many possible planets with life could have heard
this signal?
Part 1 of 3
To figure out how many light years a signal has
traveled we need to know how long since the signal left
Earth. If the signal left in 1923, distance in light years =
time since broadcast left Earth.
d = tnow - broadcast
d = 97
97 light years
Part 2 of 3
Since the radio signal travels in all directions, it
expanded as a sphere with a radius equal to the
distance it has traveled so far. To determine the
number of star systems this signal has reached, we
need to determine the volume of that sphere.
V, =
Vb…
Tutorial
A radio broadcast left Earth in 1925. How far in light years has it traveled?
If there is, on average, 1 star system per 400 cubic light years, how many star systems has this broadcast
reached?
Assume that the fraction of these star systems that have planets is 0.30 and that, in a given planetary
system, the average number of planets that have orbited in the habitable zone for 4 billion years is 0.85. How
many possible planets with life could have heard this signal?
Part 1 of 3
To figure out how many light years a signal has traveled we need to know how long since the signal left Earth.
If the signal left in 1925, distance in light years = time since broadcast left Earth.
d = tnow - tbroadcast
d =
light years
Submit
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In a globular cluster, astronomers (someday) discover a star with the same mass as our Sun, but consisting entirely of hydrogen and helium. Is this star a good place to point our SETI antennas and search for radio signals from an advanced civilization?
Group of answer choices
No, because such a star (and any planets around it) would not have the heavier elements (carbon, nitrogen, oxygen, etc.) that we believe are necessary to start life as we know it.
Yes, because globular clusters are among the closest star clusters to us, so that they would be easy to search for radio signals.
Yes, because we have already found radio signals from another civilization living near a star in a globular cluster.
No, because such a star would most likely not have a stable (main-sequence) stage that is long enough for a technological civilization to develop.
Yes, because such a star is probably old and a technological civilization will have had a long time to evolve and develop there.
Chapter 11 Solutions
Life in the Universe (4th Edition)
Ch. 11 - Prob. 1RQCh. 11 - Prob. 2RQCh. 11 - Prob. 3RQCh. 11 - How do habitable zones differ among stars of...Ch. 11 - Briefly describe the conditions under which...Ch. 11 - Why are extrasolar planets hard to detect...Ch. 11 - Briefly describe the astrometric, Doppler, and...Ch. 11 - Briefly summarize the planetary properties we can...Ch. 11 - Why does the Doppler method generally allow us to...Ch. 11 - How does the transit method tell us planetary...
Ch. 11 - How do the orbits of known extrasolar planets...Ch. 11 - Summarize the key features shown in Figure 11.20,...Ch. 11 - According to current statistics, how common arc...Ch. 11 - What types of worlds seem most likely to support...Ch. 11 - How might a stars habitable zone be wider than we...Ch. 11 - How might future imagery and spectroscopy allow us...Ch. 11 - Prob. 17RQCh. 11 - Prob. 18RQCh. 11 - What is the HertzsprungRussell diagram? How does a...Ch. 11 - Prob. 20RQCh. 11 - Date: February 16, 2025. Headline: Astronomers...Ch. 11 - Prob. 22TYUCh. 11 - Date: June 19, 2028. Headline: Spectrum Reveals...Ch. 11 - Date: November 7, 2020. Headline: New Images Show...Ch. 11 - Date: November 7, 2050. Headline: New Images Show...Ch. 11 - Date: July 20, 2020. Headline: Giant Planet Found...Ch. 11 - Date: September 15, 2045. Headline: Sun-Like Star...Ch. 11 - Prob. 28TYUCh. 11 - Date: December 13, 2033. Headline: Orphan Planet...Ch. 11 - Prob. 30TYUCh. 11 - Prob. 31TYUCh. 11 - Prob. 32TYUCh. 11 - Which method could detect a planet in an orbit...Ch. 11 - To determine a planets average density, we can use...Ch. 11 - Based on the model types shown in Figure 11.20, a...Ch. 11 - According to current statistics, about what...Ch. 11 - The term super-Earth means a planet that is (a)...Ch. 11 - Our best hope for determining that life exists on...Ch. 11 - Jupiter has had an important effect on life on...Ch. 11 - Prob. 40TYUCh. 11 - Prob. 41POSCh. 11 - Unanswered Questions. As discussed in this...Ch. 11 - Explaining the Doppler Method. Explain how the...Ch. 11 - Explaining the Transit Method. Explain how the...Ch. 11 - Comparing Methods. What are the strengths and...Ch. 11 - Super-Earth. Youve discovered a super-Earth...Ch. 11 - Stars with Habitable Planets. Based on what youve...Ch. 11 - Are Earth-Like Planets Common? Based on what you...Ch. 11 - Prob. 50IFCh. 11 - Science Fiction Planet. Choose one fictional...Ch. 11 - Number of Stars with Habitable Planets. Assume...Ch. 11 - Prob. 54IFCh. 11 - Finding Orbit Sizes. The Doppler method allows us...Ch. 11 - Finding a Planetary Mass. Using the Doppler...Ch. 11 - Transit of TrES-1. The planet TrES-1, orbiting a...Ch. 11 - The Doppler Formula. The amount of Doppler shift...Ch. 11 - Prob. 59IFCh. 11 - Future Mission. Imagine that a wealthy benefactor...Ch. 11 - Is It Worth It? Thanks to rapidly advancing...Ch. 11 - Prob. 62IFCh. 11 - Extrasolar Planet Mission. Learn about a proposed...
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