Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 20, Problem 4E
Prepare a table listing the different ways in which dust and gas can be detected in interstellar space.
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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.
Explain why interstellar molecules are best observed at radio wavelengths.
What factors resist the contraction of a cloud of interstellar matter?
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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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
- 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_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_forwardWhere does interstellar dust come from? How does it form?arrow_forward
- Describe how the 21-cm line of hydrogen is formed. Why is this line such an important tool for understanding the interstellar medium?arrow_forwardA 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_forward
- Describe the characteristics of the various kinds of interstellar gas (HII regions, neutral hydrogen clouds, ultra-hot gas clouds, and molecular clouds).arrow_forwardSuppose that you gathered a ball of interstellar gas that was equal to the size of Earth (a radius of about 6000 km). If this gas has a density of 1 hydrogen atom per cm3, typical of the interstellar medium, how would its mass compare to the mass of a bowling ball (5 or 6 kg)? How about if it had the typical density of the Local Bubble, about 0.01 atoms per cm3? The volume of a sphere is V=(4/3)R3 .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_forward
- Why are interstellar lines so narrow?arrow_forwardA) A typical dust grain has a radius of about 0.1 micrometers and a mass of 10-14 grams. Roughly how many dust particles are in a cloud containing 1000 Msun of dusty gas if 1% of the cloud's mass is in the form of dust grains? B) What surface area would be covered by these grains if you put them side by side? Assume these grains are spherical. Answer in square light-years. C) Estimate the total surface area covered by the cloud assuming it's matter density is like that of a typical molecular cloud, about 10-21 g/cm3 (Hint: first calculate the clouds volume from it's mass and density, then determine its radius using the formula for volume of a sphere) Answer in square light-years. D) Comparing all above answers, What are the chances (very roughly) that a photon passing through the cloud will hit a dust grain?arrow_forwardA typical dense core of an interstellar gas cloud has a diameter of 0.2 pc and a mass of 2 solar masses. What is the average density (in kg/m3) of this cloud core? kg/m3 Could this cloud core float on water (?w = 1,000 kg/m3)? -Yes -Noarrow_forward
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