21ST CENTURY ASTR.:STARS..(LL)-PACKAGE
6th Edition
ISBN: 9780393448450
Author: Kay
Publisher: NORTON
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Chapter 23, Problem 18QP
To determine
The ways to learn about the galaxies in universe if there were less stars or other luminous normal matter in the universe.
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Check out a sample textbook solutionStudents have asked these similar questions
Pretend that galaxies are spaced evenly, 4.0 Mpc apart, and the average mass of a galaxy is 1.0 x 101 M
What is the average density (in kg/m³) of matter in the universe? (Note: The volume of a
sphere is
4
-ar, and the mass of the sun is 2.0 x 1030 kg.)
kg/m3
Which model universe does this density value support?
flat
open
closed
why do you have to know the distance to a galaxy to find its mass?
Suppose you want to observe every galaxy within some distance. Your enterprising assistant says that instead you can observe every galaxy within double the original distance. What is the ratio of the number of galaxies you can now observe as opposed to before?
Chapter 23 Solutions
21ST CENTURY ASTR.:STARS..(LL)-PACKAGE
Ch. 23.1 - Prob. 23.1CYUCh. 23.2 - Prob. 23.2CYUCh. 23.3 - Prob. 23.3CYUCh. 23.4 - Prob. 23.4CYUCh. 23 - Prob. 1QPCh. 23 - Prob. 2QPCh. 23 - Prob. 3QPCh. 23 - Prob. 4QPCh. 23 - Prob. 5QPCh. 23 - Prob. 6QP
Ch. 23 - Prob. 7QPCh. 23 - Prob. 8QPCh. 23 - Prob. 9QPCh. 23 - Prob. 10QPCh. 23 - Prob. 11QPCh. 23 - Prob. 12QPCh. 23 - Prob. 13QPCh. 23 - Prob. 14QPCh. 23 - Prob. 15QPCh. 23 - Prob. 16QPCh. 23 - Prob. 17QPCh. 23 - Prob. 18QPCh. 23 - Prob. 19QPCh. 23 - Prob. 20QPCh. 23 - Prob. 21QPCh. 23 - Prob. 22QPCh. 23 - Prob. 23QPCh. 23 - Prob. 24QPCh. 23 - Prob. 25QPCh. 23 - Prob. 26QPCh. 23 - Prob. 27QPCh. 23 - Prob. 28QPCh. 23 - Prob. 29QPCh. 23 - Prob. 30QPCh. 23 - Prob. 31QPCh. 23 - Prob. 32QPCh. 23 - Prob. 33QPCh. 23 - Prob. 36QPCh. 23 - Prob. 37QPCh. 23 - Prob. 38QPCh. 23 - Prob. 45QP
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- Why can we not determine distances to galaxies by the same method used to measure the parallaxes of stars?arrow_forwardIn what ways are active galaxies like quasars but different from normal galaxies?arrow_forwardIf we now realize dwarf ellipticals are the most common type of galaxy, why did they escape our notice for so long?arrow_forward
- How are distant (young) galaxies different from the galaxies that we see in the universe today?arrow_forwardWhat do we now understand to be the primary difference between normal galaxies and active galaxies?arrow_forwardSuppose you were Hubble and Humason, working on the distances and Doppler shifts of the galaxies. What sorts of things would you have to do to convince yourself (and others) that the relationship you were seeing between the two quantities was a real feature of the behavior of the universe? (For example, would data from two galaxies be enough to demonstrate Hubble’s law? Would data from just the nearest galaxies-in what astronomers call “the Local Group”-suffice?)arrow_forward
- Suppose the stars in an elliptical galaxy all formed within a few million years shortly after the universe began. Suppose these stars have a range of masses, just as the stars in our own galaxy do. How would the color of the elliptical change over the next several billion years? How would its luminosity change? Why?arrow_forwardWhy did it take so long for the existence of other galaxies to be established?arrow_forwardAstronomers have been making maps by observing a slice of the universe and seeing where the galaxies lie within that slice. If the universe is isotropic and homogeneous, why do they need more than one slice? Suppose they now want to make each slice extend farther into the universe. What do they need to do?arrow_forward
- Are the galaxies red-shifting or blue-shifting? Explain. (You may find the big-bang theory helpful). Andromeda galaxy is currently approaching our galaxy with a radial velocity of 266 km/sec. How far is our galaxy from Andromeda? (Hubble’s constant, H, is 73 km/sec/MParsec). When can the two galaxies be anticipated to collide?arrow_forwardPretend that galaxies are spaced evenly, 7.0 Mpc apart, and the average mass of a galaxy is 1.0 ✕ 1011 M. What is the average density (in kg/m3) of matter in the universe? (Note: The volume of a sphere is 4/3pieR^3 and the mass of the sun is 2.0 ✕ 1030 kg.) ______ kg/m^3 Which model universe does this density value support? A: open B: flat C: closedarrow_forwardAssume that we have measured the distance to a close by galaxy, with apparent magnitude m1 = 6, to be d1 = 1Mpc. We now assume that all galaxies are similar and have therefore the same intrinsic or absolute, luminosity. Then measuring the apparent magnitude of a second galaxy to be m2 = 11, estimate the distance to that galaxy. Please answer within 90 minutes.arrow_forward
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