Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 20, Problem 25E
The 21-cm line can be used not just to find out where hydrogen is located in the sky, but also to determine how fast it is moving toward or away from us. Describe how this might work.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
velocity curve for a double line
spectroscopic binary is shown in the sketch.
The system is viewed edge-on, i.e., with an
inclination angle of i = 90°, so that the
maximum possible Doppler shifts for this
system are observed.
400
300
So = U, Ani
200
t0 = v Ain i
100
-100
-200
-300
400
O 1 2 3 1 s 1 8: 10
Time (days)
Find the orbital period of this binary in days.
Doppler Velocity (krn/sec)
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.
2GM
What is the escape velocity (in km/s) from the surface of a 1.6 Mo neutron star? From a 3.0 M. neutron star? (Hint: Use the formula for escape velocity, V.
; make sure to express quantities in units of meters, kilograms, and seconds. Assume a neutron star
has a radius of 11 km and assume the mass of the Sun is 1.99 x 1030 kg.)
1.6 Mo neutron star
km/s
3.0 Me neutron star
km/s
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...
Additional Science Textbook Solutions
Find more solutions based on key concepts
Shown below is a ray of light going from air through crown glass into water, such as going into a fish tank. Ca...
University Physics Volume 3
At which position(s), if any, does Star B rise and set?
Lecture- Tutorials for Introductory Astronomy
The mass of the jet.
Physics (5th Edition)
14.1 BIO (a) Music. When a person sings, his or her vocal cords vibrate in a repetitive pattern that has the sa...
University Physics (14th Edition)
40. An electric eel develops a potential difference of 450 V, driving a current of 0.80 A for a 1.0 ms pulse. F...
College Physics: A Strategic Approach (4th Edition)
8. A 1000 kg car pushes a 2000 kg truck that has a dead battery. When the driver steps on the accelerator, the ...
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
Knowledge Booster
Learn more about
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 double line The velocity curve for spectroscopic binary is shown in the sketch. The system is viewed edge-on, i.e., with an inclination angle of i = 90°, so that the maximum possible Doppler shifts for this system are observed. 400 U, Aini 300 200 oo - v Ain i 100 -100 -200 -300 400 o 1 2 3 +s 7 8 10 Time (daye) Find the orbital period of this binary in days. Doppler Velocity (2esun)arrow_forwardAs a star runs out of hydrogen to fuel nuclear fusion in its core, changes within the star usually cause it to leave the main sequence, expanding and cooling as it does so. Would a star with a radius 6 times that of the Sun, but a surface temperature 0.4 times that of the Sun, be more, or less luminous than the Sun? Show and explain your reasoning. You may assume the surface area of a sphere is A = 4πr2.arrow_forward= 2000 K and a radius of R, A young recently formed planet has a surface temperature T Jupiter radii (where Jupiter's radius is 7 x 107 m). Calculate the luminosity of the planet and 2 determine the ratio of the planet's luminosity to that of the Sun.arrow_forward
- Imagine a planet orbiting a star. Observations show a Doppler shift in the star's spectrum of 66 m/s over the 4.5 day orbit of the planet. What is the mass of the planet in kg? Assume the star has the same mass as the Sun (2.0 x 1030 kg), there are 365.25 days in a year, and 1AU = and 1.5 x 1011 m.arrow_forwardMany of the bright stars in the night sky are highly luminous normal blue stars (such as Acrux), and others are blue giants (such as Rigel) or red giants (such as Betelgeuse). Generally, such stars have a luminosity of 103 to 105 times that of our Sun! Ignoring any effects from our atmosphere, how bright would a star with a luminosity of 8380 solar luminosities be if it were located 620 light years from Earth? (You will need to convert some values.) W/m² For comparison, if you were 1 meter from a regular 100 W light bulb, the brightness would be 7.96 W/ m². (Since stars are not this bright, your answer should be considerably less!) Kind of amazing you can see these things, isn't it?arrow_forwardProblem 2: Black hole – the ultimate blackbody A black hole emits blackbody radiation called Hawking radiation. A black hole with mass M has a total energy of Mc², a surface area of 167G²M² /c*, and a temperature of hc³/167²KGM. a) Estimate the typical wavelength of the Hawking radiation emitted by a 1 solar mass black hole (2 × 103ºkg). Compare your answer to the size of the black hole. b) Calculate the total power radiated by a one-solar mass black hole. c) Imagine a black hole in empty space, where it emits radiation but absorbs nothing. As it loses energy, its mass must decrease; one could say "evaporates". Derive a differential equation for the mass as a function of time, and solve to obtain an expression for the lifetime of a black hole in terms of its mass.arrow_forward
- 1 Solar constant, Sun, and the 10 pc distance! The luminosity of Sun is + 4- 1026 W - 4- 1033ergs-1, The Sun is located at a distance of m from the Earth. The Earth receives a radiant flux (above its atmosphere) of F = 1365W m- 2, also known as the solar constant. What would have been the Solar contact if the Sun was at a distance of 10 pc ? 1AU 1 1.5-+ 1011arrow_forward[6/2, 7:18 AM] Ali Diaa: Telescopes are an essential tool for astronomers to study the universe. You plan to build yourown telescope that can resolve the Great Red Spot on the surface of Jupiter at a wavelength of600 nm. The farthest distance between the Earth and Jupiter is 968 × 106 km and the Great RedSpot has currently a diameter of 16,500 km.(a) Use the Rayleigh criterion to determine the diameter of the lens’ aperture of your telescopethat is needed to resolve the Great Red Spot on Jupiter.[6/2, 7:44 AM] Ali Diaa: Scientists are developing a new space cannon to shoot objects from the surface of the Earth directly into a low orbit around the Earth. For testing purposes, a projectile is fired with an initialvelocity of 2.8 km/s vertically into the sky.Calculate the height that the projectile reaches, ...(a) assuming a constant gravitational deceleration of 9.81 m/s2.(b) considering the change of the gravitational force with height.Note: Neglect the air resistance for this problem.…arrow_forwardAssuming stars to behave as black bodies stefan-boltzmann law to show that the luminosity of a star is related to its surface temperature and size in the following way: L = 4(3.14)R^2oT^4 where o= 5.67 ×10^-8 Wm^-2 K-4 is the stefan- boltzmann constant. Then use this expression together with the knowledge that the sun has a surface temperature of 5700k and radius 695 500km to calculate the luminosity of the Sun in units of Wattsarrow_forward
- Small differences in the wavelengths in the sun’s spectrum are detected when measurements are taken from different parts of the sun’s disk. Specifi cally, measurements of the 656-nm line in hydrogen taken from opposite sides on the sun’s equator—one side approaching Earth and the other receding—differ from each other by 0.0090 nm. Use this information to fi nd the rotational period of the sun’s equator. Express your answer in days. (The sun’s equatorial radius is 6.96 x 108 m.)arrow_forwardMany of the bright stars in the night sky are highly luminous normal blue stars (such as Acrux), and others are blue giants (such as Rigel) or red giants (such as Betelgeuse). Generally, such stars have a luminosity of 103 to 105 times that of our Sun! Ignoring any effects from our atmosphere, how bright would a star with a luminosity of 60900 solar luminosities be if it were located 532 light years from Earth? (You will need to convert some values.) W/m² For comparison, if you were 1 meter from a regular 100 W light bulb, the brightness would be 7.96 W/m². (Since stars are not this bright, your answer should be considerably less!) Kind of amazing you can see these things, isn't it?arrow_forward5... Calculate the fraction of time a spacecraft spends in daylight given a celestial body with a radius 5,709 km at an altitude of 686 km. Use the extreme case (minimum alpha) when the angle between the orbit plane and the direction of the sunlight is 0.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
AstronomyPhysicsISBN:9781938168284Author:Andrew Fraknoi; David Morrison; Sidney C. WolffPublisher:OpenStax
Stars and Galaxies (MindTap Course List)PhysicsISBN:9781337399944Author:Michael A. SeedsPublisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning
Astronomy
Physics
ISBN:9781938168284
Author:Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher:OpenStax
Stars and Galaxies (MindTap Course List)
Physics
ISBN:9781337399944
Author:Michael A. Seeds
Publisher:Cengage Learning
Foundations of Astronomy (MindTap Course List)
Physics
ISBN:9781337399920
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning