Foundations of Astronomy (MindTap Course List)
14th Edition
ISBN: 9781337399920
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
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Textbook Question
Chapter 8, Problem 7P
If a sunspot has a temperature of 4200 K and the average solar photosphere has a temperature of 5780 K, how much more energy is emitted in 1 second from a square meter of the photosphere compared to a square meter of the sunspot? (Hint: Use the Stefan-Boltzmann law, Eq. 7-1.)
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what the Sun would look like from Earth if the entire photosphere were the same temperature as a sunspot.
An image of the disk of the Sun shows a higher brightness at the centre compared to the edges. Explain with the aid of a sketch the reasons for this darkening at the limb of the solar disk.
In images of the solar photosphere there are small regions of the solar disk, about 500 km across, which are about 2.5 times brighter that the surrounding photosphere. Assuming a temperature of 5800 K for the background photosphere, calculate the temperature of these photospheric bright points.
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a) At solar maximum sunspots might cover up to 0.4% of the total area of the Sun. If the sunspots have a temperature of 3800 K and the surrounding photosphere has a temperature of 6000 K, calculate the fractional change (as a percentage) in the luminosity due to the presence of the sunspots.
b) A star of the same stellar class as the Sun is observed regularly over many years, and a time series of its bolometric apparent magnitude is collected. What would be the signal in this time series which indicated that the star had a magnetic dynamo similar to the Sun? Briefly describe two or three possible sources of other signals which could confuse the interpretation of the data.
Chapter 8 Solutions
Foundations of Astronomy (MindTap Course List)
Ch. 8 - Prob. 1RQCh. 8 - Prob. 2RQCh. 8 - Prob. 3RQCh. 8 - Prob. 4RQCh. 8 - Prob. 5RQCh. 8 - Prob. 6RQCh. 8 - What evidence can you give that granulation is...Ch. 8 - Prob. 8RQCh. 8 - Prob. 9RQCh. 8 - Prob. 10RQ
Ch. 8 - Prob. 11RQCh. 8 - Prob. 12RQCh. 8 - Prob. 13RQCh. 8 - Prob. 14RQCh. 8 - Energy can be transported by convection,...Ch. 8 - Prob. 16RQCh. 8 - Prob. 17RQCh. 8 - Prob. 18RQCh. 8 - Prob. 19RQCh. 8 - Meridional is derived from meridian. Look up the...Ch. 8 - Prob. 21RQCh. 8 - Prob. 22RQCh. 8 - How can solar flares affect Earth?Ch. 8 - Prob. 24RQCh. 8 - Why does nuclear fusion require high temperatures...Ch. 8 - Prob. 26RQCh. 8 - Four protons are combined in the proton-proton...Ch. 8 - Give an example of a charged subatomic particle...Ch. 8 - Prob. 29RQCh. 8 - Prob. 30RQCh. 8 - Prob. 31RQCh. 8 - Prob. 32RQCh. 8 - Prob. 33RQCh. 8 - The radius of the Sun is 0.7 million km. What...Ch. 8 - Prob. 2PCh. 8 - Prob. 3PCh. 8 - What is the angular diameter of a star the same...Ch. 8 - If a sunspot has a temperature of 4200 K and the...Ch. 8 - How many watts of radiation does a 1-meter-square...Ch. 8 - If a sunspot has a temperature of 4200 K and the...Ch. 8 - Prob. 8PCh. 8 - Prob. 9PCh. 8 - Prob. 10PCh. 8 - Prob. 11PCh. 8 - Prob. 12PCh. 8 - Prob. 13PCh. 8 - Prob. 14PCh. 8 - The United States consumes about 2.5 1019 J of...Ch. 8 - Prob. 16PCh. 8 - Prob. 1SOPCh. 8 - Prob. 2SOPCh. 8 - Whenever there is a total solar eclipse, you can...Ch. 8 - Prob. 2LTLCh. 8 - Prob. 3LTLCh. 8 - Prob. 4LTLCh. 8 - The two images here show two solar phenomena. What...Ch. 8 - Prob. 6LTL
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- If a sunspot has a temperature of 4200 K and the sunspot can be considered a blackbody, what is the wavelength of maximum intensity in nm units and what color is associated with this wavelength? Is this the color we see the sunspot as from Earth? Why or why not? (Hint: Refer to Wiens law, Eq. 7-2.)arrow_forwardAssuming an average sunspot cycle of 11 years, how many revolutions does the equator of the Sun make during that one cycle? Do higher latitudes make more or fewer revolutions compared to the equator?arrow_forwardWhat do measurements of the number of neutrinos emitted by the Sun tell us about conditions deep in the solar interior?arrow_forward
- Suppose an eruptive prominence rises at a speed of 150 km/s. If it does not change speed, how far from the photosphere will it extend after 3 hours? How does this distance compare with the diameter of Earth?arrow_forwardThe radius of the Sun is 0.7 million km. What percentage of the radius is taken up by the chromosphere? (Hint: Refer to Figure 8-1.)arrow_forwardStarting from the core of the Sun and going outward, the temperature decreases. Yet, above the photosphere, the temperature increases. How can this be?arrow_forward
- Why do sunspots look dark?arrow_forwardWhat is the average density of the Sun? How does it compare to the average density of Earth?arrow_forwardIf the temperature at the centre of the sun is 15,000,000 K and the temperature of the photosphere is 5,800 K, what is the ratio of the temperature at the centre of the Sun compared to the photosphere? Express your final answer in the fully factorised form x : 1, where x is a number that you should determine to an appropriate number of significant figures and write it using scientific notation.arrow_forward
- Assuming that (1) the solar luminosity has been constant since the Sun formed, and (2) the Sun was initially of uniform composition throughout, as described by Table 9.2, estimate how long it would take the Sun to convert all of its original hydrogen into helium. [Hint: Calculate the mass of hydrogen in the sun and then divide it by the rate of hydrogen fusion (PPT slide 47.)]arrow_forwardUse Wein's law to determine the wavelength corresponding to the peak of the black body curve (a) in the core of the Sun, where the temperature is 10^7, (b) in the solar convection zone (10^5), and (c) just below the solar photosphere (10^4K). What form (visible, infrared, X-ray, etc.) does radiation take in each case?arrow_forwardA sunspot has a temperature of about 4200 K. Use the Stefan-Boltzmann law to calculate how much energy is emitted in one second from 1 square meter of the sunspot.arrow_forward
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