Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 17, Problem 31E
What would you say to a friend who made this statement, “The visible-light spectrum of the Sun shows weak hydrogen lines and strong calcium lines. The Sun must therefore contain more calcium than hydrogen.”?
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Students have asked these similar questions
Assuming that the Sun is a blackbody with a temperature of 6,000 K, at what wavelength does it radiate the most energy? [4.8 x 10‐7 m]
If a star has a surface temperature of 25,000 K (2.50 ✕ 104 K), at what wavelength (in nm) will it radiate the most energy?
nm
Is this a cool or hot star? (Give your answer relative to the Sun.)
coolhot
Why don’t we see hydrogen Balmer lines in the spectra of stars with temperatures of 45,000 K?
a.
There is no hydrogen in stars this hot.
b.
The stars are hot enough that most of the hydrogen is ionized and the atoms cannot absorb energy.
c.
These stars are so cool that nearly all of the electrons in the hydrogen atom are in the ground state.
d.
Stars of this temperature are too cool to produce an absorption spectrum.
e.
Stars of this temperature are too hot to produce an absorption spectrum.
Chapter 17 Solutions
Astronomy
Ch. 17 - What two factors determine how bright a star...Ch. 17 - Explain why color is a measure of a star’s...Ch. 17 - What is the main reason that the spectra of all...Ch. 17 - What elements are stars mostly made of? How do we...Ch. 17 - What did Annie Cannon contribute to the...Ch. 17 - Name five characteristics of a star that can be...Ch. 17 - How do objects of spectral types L, T, and Y...Ch. 17 - Do stars that look brighter in the sky have larger...Ch. 17 - The star Antares has an apparent magnitude of 1.0,...Ch. 17 - Based on their colors, which of the following...
Ch. 17 - Order the seven basic spectral types from hottest...Ch. 17 - What is the defining difference between a brown...Ch. 17 - If the star Sirius emits 23 times more energy than...Ch. 17 - How would two stars of equal luminosity-one blue...Ch. 17 - Table 17.2 lists the temperature ranges that...Ch. 17 - Suppose you are given the task of measuring the...Ch. 17 - Star X has lines of ionized helium in its...Ch. 17 - The spectrum of the Sun has hundreds of strong...Ch. 17 - What are the approximate spectral classes of stars...Ch. 17 - Look at the chemical elements in Appendix K. Can...Ch. 17 - Appendix I lists some of the nearest stars. Are...Ch. 17 - Appendix J lists the stars that appear brightest...Ch. 17 - What star appears the brightest in the sky (other...Ch. 17 - Suppose hominids one million years ago had left...Ch. 17 - Why can only a lower limit to the rate of stellar...Ch. 17 - Why do you think astronomers have suggested three...Ch. 17 - Sam, a college student, just bought a new car....Ch. 17 - Would a red star have a smaller or larger...Ch. 17 - Two stars have proper motions of one arcsecond per...Ch. 17 - Suppose there are three stars in space, each...Ch. 17 - What would you say to a friend who made this...Ch. 17 - In Appendix J, how much more luminous is the most...Ch. 17 - Verify that if two stars have a difference of five...Ch. 17 - As seen from Earth, the Sun has an apparent...Ch. 17 - An astronomer is investigating a faint star that...Ch. 17 - The center of a faint but active galaxy has...Ch. 17 - You have enough information from this chapter to...Ch. 17 - Do the previous problem again, this time using the...Ch. 17 - Star A and Star B have different apparent...Ch. 17 - Star A and Star B have different apparent...Ch. 17 - The star Sirius A has an apparent magnitude of 1.5...Ch. 17 - Our Sun, a type G star, has a surface temperature...
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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
- Hydrogen accounts for about 75% by mass of the matter at the surfaces of most stars. However, the absorption lines of hydrogen are strongest (of highest intensity) in the spectra of stars with a surface temperature of about 9000 K. They are weaker in the sun spectrum and are essentially nonexistent in very hot (temperatures above 25,000 K) or rather cool (temperatures below 3500 K) stars. Speculate as to why surface temperature affects the hydrogen absorption lines that we observe.arrow_forwardExplain how we can deduce the temperature of a star by determining its color.arrow_forwardThe spectrum of the Sun has hundreds of strong lines of nonionized iron but only a few, very weak lines of helium. A star of spectral type B has very strong lines of helium but very weak iron lines. Do these differences mean that the Sun contains more iron and less helium than the B star? Explain.arrow_forward
- If one star has a temperature of 5,000 K and another star has a temperature of 8,500 , how much more energy per second will the hotter star radiate from each square meter of its surface? (asks for the difference, not ratio)arrow_forwardIn hydrogen, the transition from level 2 to level 1 has a rest wavelength of 121.6 nm. Find the speed for a star in which this line appears at wavelength 120.5 mm. What about at 122.4 nm? Express your answer to three significant figures and include the appropriate units.arrow_forwardWhy don’t we see hydrogen Balmer lines in the spectra of stars with temperatures of 3,200 K? a. There is no hydrogen in stars this cool. b. The stars are hot enough that most of the hydrogen is ionized and the atoms cannot absorb energy. c. These stars are so cool that nearly all of the hydrogen atoms are in the ground state. d. Stars of this temperature are too cool to produce an absorption spectrum. e. Stars of this temperature are too hot to produce an absorption spectrum.arrow_forward
- A star is moving toward Earth with a radial velocity (speed directly toward or away from Earth) of 40,000 km/s. If we take a spectrum of this star’s light, will we find it to be red shifted or blue shifted? By what fraction are the wavelengths in this star’s spectrum shifted? [Answer: λ0/λ = 0.88]arrow_forwardA star has a luminosity (power output) of 9.2x1026 W and a diameter of 6.1x108 m. What is its surface temperature? (Give your answer in SI units and include the units in your answer.)arrow_forward
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