Horizons: Exploring the Universe (MindTap Course List)
14th Edition
ISBN: 9781305960961
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
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Chapter 20, Problem 4P
If a star must remain on the main sequence for at least 4 billon years for life to evolve to intelligence, what is the most massive a star can be and still possibly harbour intelligent life on one of its planets? (Hints. See Reasoning with Numbers 9-1 and Appendix Table A-7.)
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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.
Suppose that stars were born at random times over the last 10e10 years. The rate ofstar formation is simply the number of stars divided by 10e10 years. The fraction ofstars with detected extrasolar planets is at least 9 %. The rate of star formation can bemultiplied by this fraction to find the rate planet formation. How often (in years) doesa planetary system form in our galaxy? Assume the Milky Way contains 7 × 10e11 stars.
I've done this problem 3 different times from scratch and looked at similar problems here. Each time my answer is 1.587 (1.59 rounded to 2 significant figures), but when I submit, it says the answer is wrong. What do you think?
A newly discovered orange dwarf star has a surface temperature of approximately 5185 K. How far would its Goldilocks Zone be from the star if an astrologist wanted to look for potentially habitable planets? And how wide would the zone be?
Chapter 20 Solutions
Horizons: Exploring the Universe (MindTap Course List)
Ch. 20 - If life is based on information, what is that...Ch. 20 - How does the DNA molecule produce a copy of...Ch. 20 - What would happen to a life-form if the genetic...Ch. 20 - What would happen to a life-form if the...Ch. 20 - Give an example of natural selection acting on new...Ch. 20 - Prob. 6RQCh. 20 - Why do scientists generality think that liquid...Ch. 20 - Prob. 8RQCh. 20 - What is the significance of the Miller-Urey...Ch. 20 - Prob. 10RQ
Ch. 20 - Prob. 11RQCh. 20 - Why is it reasonable to suspect that travel...Ch. 20 - How does the stability of technological...Ch. 20 - Prob. 14RQCh. 20 - Prob. 15RQCh. 20 - Prob. 16RQCh. 20 - How Do We know? Why are scientists confident that...Ch. 20 - Do you expect that hypothetical alien recipients...Ch. 20 - Prob. 2DQCh. 20 - Prob. 3DQCh. 20 - A single human cell encloses about 1.5 m of DNA,...Ch. 20 - If you represent Earth’s history by a line 1 m...Ch. 20 - Prob. 3PCh. 20 - If a star must remain on the main sequence for at...Ch. 20 - Prob. 5PCh. 20 - Prob. 6PCh. 20 - Prob. 7PCh. 20 - Calculate the numb of communicative civilizations...Ch. 20 - The star cluster shown in the image in Figure UN...Ch. 20 - Prob. 2LTL
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- If you could search for life in the galaxy shown in this image, would you look among stars in the disk, in the central bulge, in the halo, or in all of those places? Discuss the factors that influence your decision.arrow_forwardWhy are upper-main-sequence (high-luminosity) host stars unlikely sites for intelligent civilizations?arrow_forwardExplain pre main sequence evolution, early post main sequence evolution and advanced evolutionary stages.arrow_forward
- 1) How massive would Earth had been if it had accreted hydrogen compounds in addition to the sme properties listed in table 7.1? (Assume the same properties of the ingredients as listed in the table) 2) Now imagine that Earth had been able to capture hydrogen and helium gas in the same proportions as listed in the table. How massive would it have been?arrow_forwardKepler-444 is one of many stars with terrestrial planets that is over 10 billion a) What do you think the spectral type of Kepler-444 might be? b) How do stars of this spectral type end their lives? c) If evolution followed a similar course on a habitable pranet around a star similar to Kepler-444, it would be 5 billion years more advanced than we are. Let’s try to project our future and see what happens. In particular, suppose our civilization gets motivated enough to colonize another planet. Kepler indicates that most stars have potentially habitable (and colonizable) planets, so roughly how far away is the typical “nearest" planet? d) The New Horizons probe on its way to Pluto took 9 years to travel 30 AU. If we could send colony ships with the same average speed, roughly how long would it take to reach the typical nearest planet? уears old.arrow_forwardImagine that in the future, scientists plan on colonizing planets that orbit other stars. Based on your knowledge of the life cycle of stars, decide which type of star (High mass or Low mass) the planet should orbit that would allow for human life to safely live on that planet for the longest period of time. Explain your answer using examples from the life cycle of each star.arrow_forward
- What is an isochromat?arrow_forwardWhat is the wavelength shift (delta) (h) of a exoplanetery system at a wavelength of X angstroms if an exoplan et creates a doppler shift in its star of 2.4 km per second? Use the doppler equation (delta)/(h) = v/carrow_forwardH5. A star with mass 1.05 M has a luminosity of 4.49 × 1026 W and effective temperature of 5700 K. It dims to 4.42 × 1026 W every 1.39 Earth days due to a transiting exoplanet. The duration of the transit reveals that the exoplanet orbits at a distance of 0.0617 AU. Based on this information, calculate the radius of the planet (expressed in Jupiter radii) and the minimum inclination of its orbit to our line of sight. Follow up observations of the star in part reveal that a spectral feature with a rest wavelength of 656 nm is redshifted by 1.41×10−3 nm with the same period as the observed transit. Assuming a circular orbit what can be inferred about the planet’s mass (expressed in Jupiter masses)?arrow_forward
- If you detected radio signals with an average wavelength of 68 cm and suspected that they came from a civilization on a distant Earth-like exoplanet, roughly how much of a change in wavelength (in cm) should you expect to detect as a result of the orbital motion of the distant exoplanet? (Hint: Use the Doppler shift formula.) (Note: Earth's orbital velocity is 30 km/s.)arrow_forwardwhy do scientists generally think that liquid water is necessary for the origin of life? (astronomy)arrow_forwardTutorial 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…arrow_forward
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