Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 20, Problem 32E
Would you expect to be able to detect an H II region in X-ray emission? Why or why not? (Hint: You might apply Wien’s law)
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What is the wavelength in micrometers of peak emission for a black body at 33.5°C? (c = 3.0 × 108 m/s, Wien displacement law constant is 2.9 × 10-3 m ∙ K, σ = 5.67 × 10-8 W/m2 ∙ K4). Please give your answer with one decimal place.
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Chapter 20 Solutions
Astronomy
Ch. 20 - Identify several dark nebulae in photographs in...Ch. 20 - Why do nebulae near hot stars look red? Why do...Ch. 20 - Describe the characteristics of the various kinds...Ch. 20 - Prepare a table listing the different ways in...Ch. 20 - Describe how the 21-cm line of hydrogen is formed....Ch. 20 - Describe the properties of the dust grains found...Ch. 20 - Why is it difficult to determine where cosmic rays...Ch. 20 - What causes reddening of starlight? Explain how...Ch. 20 - Why do molecules, including H2 and more complex...Ch. 20 - Why can’t we use visible light telescopes to study...
Ch. 20 - The mass of the interstellar medium is determined...Ch. 20 - Where does interstellar dust come from? How does...Ch. 20 - Figure 20.2 shows a reddish glow around the star...Ch. 20 - If the red glow around Antares is indeed produced...Ch. 20 - Even though neutral hydrogen is the most abundant...Ch. 20 - The terms H II and H2 are both pronounced “H two.”...Ch. 20 - Suppose someone told you that she had discovered H...Ch. 20 - Describe the spectrum of each of the following: A....Ch. 20 - According to the text, a star must be hotter than...Ch. 20 - From the comments in the text about which kinds of...Ch. 20 - One way to calculate the size and shape of the...Ch. 20 - New stars form in regions where the density of gas...Ch. 20 - Thinking about the topics in this chapter, here is...Ch. 20 - Stars form in the Milky Way at a rate of about 1...Ch. 20 - The 21-cm line can be used not just to find out...Ch. 20 - Astronomers recently detected light emitted by a...Ch. 20 - We can detect 21-cm emission from other galaxies...Ch. 20 - We have said repeatedly that blue light undergoes...Ch. 20 - Suppose that, instead of being inside the Local...Ch. 20 - Suppose that, instead of being inside the Local...Ch. 20 - A molecular cloud is about 1000 times denser than...Ch. 20 - Would you expect to be able to detect an H II...Ch. 20 - Suppose that you gathered a ball of interstellar...Ch. 20 - At the average density of the interstellar medium,...Ch. 20 - Consider a grain of sand that contains 1 mg of...Ch. 20 - H II regions can exist only if there is a nearby...Ch. 20 - In the text, we said that the five-times ionized...Ch. 20 - Dust was originally discovered because the stars...Ch. 20 - How would the density inside a cold cloud (T=10K)...Ch. 20 - The text says that the Local Fluff, which...
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- Neutral hydrogens are detected with their emission lines of 21cm. What is the energy of a photon in such a line, and in which waveband would this line be observed?arrow_forwardWhat will be the energy associated with a blue photon (in Joules), if the frequency of the blue light is 650 THz (Terahertz (THz); 1 Tera – 1012y? [Hint: Use Planck's cquation: E = hf to calculate the photon energy! h - Planck's constant – 6,63 × 10-4 Js – 4.14 ×1015 eVs] A. 650×1012 J B. 6.5×10° J C. 4.3x1015 J D. 4.3×10-19 J E. 4.3x1019 Jarrow_forwardSuppose we detect red photons at 656 nm emitted by electrons dropping from the n = 3 to the n = 2 orbital in hydrogen. The hydrogen is in an interstellar cloud at 5000k. If the cloud were heted to 10000 K, what would be the wavelength of the photons emitted by the transition? a) 328 nm b) 656 nm c) 1312 nm d) 658 nm e) 654 nmarrow_forward
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