21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Chapter 19, Problem 28QP
To determine
To explain why some black holes reveal their presence and some does not.
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Chapter 19 Solutions
21st Century Astronomy
Ch. 19.1 - Prob. 19.1ACYUCh. 19.1 - Prob. 19.1BCYUCh. 19.2 - Prob. 19.2CYUCh. 19.3 - Prob. 19.3CYUCh. 19.4 - Prob. 19.4CYUCh. 19 - Prob. 1QPCh. 19 - Prob. 2QPCh. 19 - Prob. 3QPCh. 19 - Prob. 4QPCh. 19 - Prob. 5QP
Ch. 19 - Prob. 6QPCh. 19 - Prob. 7QPCh. 19 - Prob. 8QPCh. 19 - Prob. 9QPCh. 19 - Prob. 10QPCh. 19 - Prob. 11QPCh. 19 - Prob. 12QPCh. 19 - Prob. 13QPCh. 19 - Prob. 14QPCh. 19 - Prob. 15QPCh. 19 - Prob. 16QPCh. 19 - Prob. 17QPCh. 19 - Prob. 18QPCh. 19 - Prob. 19QPCh. 19 - Prob. 20QPCh. 19 - Prob. 21QPCh. 19 - Prob. 22QPCh. 19 - Prob. 23QPCh. 19 - Prob. 24QPCh. 19 - Prob. 25QPCh. 19 - Prob. 26QPCh. 19 - Prob. 27QPCh. 19 - Prob. 28QPCh. 19 - Prob. 29QPCh. 19 - Prob. 30QPCh. 19 - Prob. 31QPCh. 19 - Prob. 32QPCh. 19 - Prob. 33QPCh. 19 - Prob. 34QPCh. 19 - Prob. 35QPCh. 19 - Prob. 36QPCh. 19 - Prob. 37QPCh. 19 - Prob. 38QPCh. 19 - Prob. 39QPCh. 19 - Prob. 40QPCh. 19 - Prob. 41QPCh. 19 - Prob. 42QPCh. 19 - Prob. 43QPCh. 19 - Prob. 44QPCh. 19 - 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_forwardAn observational survey of distant galaxies is undertaken that involves measuring their distances using cepheid variables and red-shifts using spectroscopy. Explain how cepheid variables can be used to measure the distances to galaxies. A spectral line is observed whose wavelength in the laboratory is de length of this spectral line observed in each galaxy, Xo, is listed in the table, along with the distance, d, to the galaxy. Determine the red-shift and the recession velocity of each galaxy and tabulate your results by making a copy of the table and filling in the blank spaces. Sketch a Hubble diagram using your results and determine the value of the Hubble constant Ho in units of km s-1 Mpc. 650 nm. The wave- Galaxy 1 652.69 Galaxy 2 Galaxy 3 Galaxy 4 Galaxy 5 653.01 do (nm) d (Mpc) 658.54 662.18 681.63 17 19 54 77 200 v (km s-1)arrow_forwardwhat evidence is there that galaxies collide and merge?arrow_forward
- When two galaxies collide, the stars inside them are not likely to be much affected, because the __________ stars is so large compared to their diameters. However, the _______ of stars and gas can be changed, altering the appearance of the galaxies. Astronomers have determined that such collisions are seen more often in ____________. When two galaxies of roughly equal size collide, astronomers call it a _______ of galaxies; but when a small galaxy collides with a much larger one, the process is called ___________. When a galaxy has a significant amount of its interstellar gas compressed by a collision, leading to the birth of many new stars, astronomers call it a __________ galaxy.arrow_forwardPretend that galaxies are spaced evenly, 8.0 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? Which model universe does this density value support?arrow_forwardA black hole (m = 2.90 x 10^9 Ms) sits in the middle of the M87 galaxy. Calculate its gravitational field intensity at a distance of three times its Schwarzschild radius.1 Ms = 1.99 x 10^30 kgarrow_forward
- 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 closedarrow_forwardFigure 2 shows the "rotation curve" of NGC 2742. It plots the “radial velocity (V)" (how fast material is moving either toward or away from us) that is measured for objects at different distances (R = radius") from the center of the galaxy. The center of the galaxy is at 0 kpc (kiloparsecs) with a speed of 9 km/sec away from us. (These velocities have been corrected for the observed tilt of the galaxy and represent true orbital velocities of the stars and gas.) 200 100 U4779 -100 As you can see, one side of the galaxy is moving with a negative velocity (spinning toward us), while the other side has a positive velocity (spinning away from us). Using Newton's gravity equation, we will be able to determine the gravitational mass of the entire galaxy and how the mass varies versus distance from the galaxy's center. -200 -8 8 -4 Radius (kpc) Read the following text carefully and follow the instructions: Select five radii spaced evenly from 0-10 kpc across the galaxy. Your selections should…arrow_forwardIn what ways are active galaxies like quasars but different from normal galaxies?arrow_forward
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