Universe: Stars And Galaxies
6th Edition
ISBN: 9781319115098
Author: Roger Freedman, Robert Geller, William J. Kaufmann
Publisher: W. H. Freeman
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Chapter 18, Problem 6Q
To determine
The stationary absorption lines and what sort of spectra they are seen. Also, determine if they give evidence for the existence of the interstellar medium.
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Students have asked these similar questions
What evidence can you cite that the interstellar medium contains both gas and dust? (Select all that apply.)
(1)The dust of the interstellar medium can be detected from the emission lines of elements heavier than iron.
(2)The dust of the interstellar medium can be detected by the extinction of light from distant stars.
(3)The dust of the interstellar medium can be detected by the scattering of blue light from distant or embedded objects.
(4)The gas of the interstellar medium can be detected from the radiation of ultraviolet photons.
(5)The gas of the interstellar medium can be detected from the radiation of photons of wavelength 21 cm.
(6)The gas of the interstellar medium can be detected from the absorption lines present in the light from distant stars, which must be caused by a medium of a density and temperature other than that of the stars emitting the light.
How are giant molecular clouds (GMCs), the loci of most star formation, themselves formed out of diffuse interstellar gas?
What processes determine the distribution of physical conditions within star-forming regions, and why does star formation occur in only a small fraction of the available gas?
How is the rate at which stars form determined by the properties of the natal GMC or, on a larger scale, of the interstellar medium (ISM) in a galaxy?
What determines the mass distribution of forming stars, the initial mass function (IMF)?
Most stars form in clusters (Lada & Lada 2003); how do stars form in such a dense environment and in the presence of enormous radiative and mechanical feedback from other YSOs?
Why are interstellar lines so narrow?
Chapter 18 Solutions
Universe: Stars And Galaxies
Ch. 18 - Prob. 1QCh. 18 - Prob. 2QCh. 18 - Prob. 3QCh. 18 - Prob. 4QCh. 18 - Prob. 5QCh. 18 - Prob. 6QCh. 18 - Prob. 7QCh. 18 - Prob. 8QCh. 18 - Prob. 9QCh. 18 - Prob. 10Q
Ch. 18 - Prob. 11QCh. 18 - Prob. 12QCh. 18 - Prob. 13QCh. 18 - Prob. 14QCh. 18 - Prob. 15QCh. 18 - Prob. 16QCh. 18 - Prob. 17QCh. 18 - Prob. 18QCh. 18 - Prob. 19QCh. 18 - Prob. 20QCh. 18 - Prob. 21QCh. 18 - Prob. 22QCh. 18 - Prob. 23QCh. 18 - Prob. 24QCh. 18 - Prob. 25QCh. 18 - Prob. 26QCh. 18 - Prob. 27QCh. 18 - Prob. 28QCh. 18 - Prob. 29QCh. 18 - Prob. 30QCh. 18 - Prob. 31QCh. 18 - Prob. 32QCh. 18 - Prob. 33QCh. 18 - Prob. 34QCh. 18 - Prob. 35QCh. 18 - Prob. 36QCh. 18 - Prob. 37QCh. 18 - Prob. 38QCh. 18 - Prob. 39QCh. 18 - Prob. 40QCh. 18 - Prob. 41QCh. 18 - Prob. 42QCh. 18 - Prob. 43QCh. 18 - Prob. 44QCh. 18 - Prob. 45QCh. 18 - Prob. 46QCh. 18 - Prob. 47QCh. 18 - Prob. 48QCh. 18 - Prob. 49Q
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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
- A molecular cloud is about 1000 times denser than the average of the interstellar medium. Let’s compare this difference in densities to something more familiar. Air has a density of about 1 kg/m3, so something 1000 times denser than air would have a density of about 1000 kg/m3. How does this compare to the typical density of water? Of granite? (You can find figures for these densities on the internet.) Is the density difference between a molecular cloud and the interstellar medium larger or smaller than the density difference between air and water or granite?arrow_forwardHow would the density inside a cold cloud (T=10K) compare with the density of the ultra-hot interstellar gas (T=106K) if they were in pressure equilibrium? (It takes a large cloud to be able to shield its interior from heating so that it can be at such a low temperature.) (Hint: In pressure equilibrium, the two regions must have nT equal, where n is the number of particles per unit volume and T is the temperature.) Which region do you think is more suitable for the creation of new stars? Why?arrow_forwardDescribe how the 21-cm line of hydrogen is formed. Why is this line such an important tool for understanding the interstellar medium?arrow_forward
- Consider a grain of sand that contains 1 mg of oxygen (a typical amount for a medium-sized sand grain, since sand is mostly SiO2). How many oxygen atoms does the grain contain? What is the radius of the sphere you would have to spread them out over if you wanted them to have the same density as the interstellar medium, about 1 atom per cm3? You can look up the mass of an oxygen atom.arrow_forwardWhere does interstellar dust come from? How does it form?arrow_forwardThe mass of the interstellar medium is determined by a balance between sources (which add mass) and sinks (which remove it). Make a table listing the major sources and sinks, and briefly explain each one.arrow_forward
- 1. If a star has a surface temperature of 3000 K but a luminosity 150 times greater than our Sun, what size is this star? Give your answer in units of the solar radius. 2. At what wavelengths do stars of surface temperates 20 000 K, 10 000 K, and 3000 K have their peak intensity? 3. If the Hα absorption line in the spectrum of a galaxy is observed at a wavelength of 6715 ˚A, at what speed is the galaxy moving away from us?arrow_forward(a) Rank the following components of the interstellar medium in order of the wavelengths at which they are observed, longest wavelength first: clouds of neutral hydrogen, coronal gas, interstellar dust, nebulae. Longest to Shortest? (b) Rank the same material in order of decreasing temperature from hottest to coolest. Hottest to Coolest?arrow_forwardAbsorption lines produced when starlight travels through the interstellar medium indicate that some components of the interstellar medium are cold and of a very low density because a. the lines are blueshifted. b. the lines are redshifted. c. the lines are extremely broad. d. the lines are extremely narrow. e. the lines are much darker than the stellar lines.arrow_forward
- Explain why interstellar molecules are best observed at radio wavelengths.arrow_forwardYou record the spectrum of a distant star using a telescope on the ground on Earth. Upon analysing the spectrum, you discover absorption lines spaced at intervals typical of oxygen atoms. Which of the following are possible interpretations of this evidence? Select all that apply. The width of the spectral lines gives the diameter of the star The star is likely orbited by habitable planets with breathable atmospheres. The height of the spectral lines above the star's general blackbody spectral curve tells us how much oxygen is in the star The atmosphere of Earth contains oxygen The red or blueshift of the set of lines can tell us the speed of the star's motion toward or away from usarrow_forward5. A star whose temperature is 8000 K has a peak wavelength of 362.5 nm, according to Wien's Law. If the star is in the Andromeda Galaxy, which is moving towards us at about 402,000 km/hour, what would an observer on Earth see as the peak wavelength for this star (show your work, and use c = 300,000 km/s)?arrow_forward
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