21st Century Astronomy
6th Edition
ISBN: 9780393428063
Author: Kay
Publisher: NORTON
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Question
Chapter 20.3, Problem 20.3CYU
To determine
The property that is detectable for both dark matter and the supermassive black hole at the centre of the Milky Way.
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Students have asked these similar questions
What is the only viable explanation for so much mass in so small a region at the core of our galaxy?
a.
a tight cluster of stars
b.
many neutron stars
c.
many stellar black holes
d.
a single massive black hole
e.
none of the above
What happens when galaxies collide?
A. Star collisions will be rare but the shapes of the galaxies will be largely distorted.
B. The shapes of the galaxies will be largely distorted and many of the stars of one galaxy will collide with stars of the other galaxy.
C. The shapes of the galaxies will be distorted and many stars will collide with stars of the other galaxy, as well as with other stars in the same galaxy.
D. Star collisions will be rare and the two galaxies will just pass through each other without any changes.
Is the answer A? Thank you!
What triggers the nucleus of a galaxy into activity?
a.
a nova explosion
b.
a type I supernova explosion
c.
a hypernova explosion
d.
a type II supernova explosion
e.
none of the above
Chapter 20 Solutions
21st Century Astronomy
Ch. 20.1 - Prob. 20.1CYUCh. 20.2 - Prob. 20.2CYUCh. 20.3 - Prob. 20.3CYUCh. 20.4 - Prob. 20.4CYUCh. 20 - Prob. 1QPCh. 20 - Prob. 2QPCh. 20 - Prob. 3QPCh. 20 - Prob. 4QPCh. 20 - Prob. 5QPCh. 20 - Prob. 6QP
Ch. 20 - Prob. 7QPCh. 20 - Prob. 8QPCh. 20 - Prob. 9QPCh. 20 - Prob. 10QPCh. 20 - Prob. 11QPCh. 20 - Prob. 12QPCh. 20 - Prob. 13QPCh. 20 - Prob. 14QPCh. 20 - Prob. 15QPCh. 20 - Prob. 16QPCh. 20 - Prob. 17QPCh. 20 - Prob. 18QPCh. 20 - Prob. 19QPCh. 20 - Prob. 20QPCh. 20 - Prob. 21QPCh. 20 - Prob. 22QPCh. 20 - Prob. 23QPCh. 20 - Prob. 24QPCh. 20 - Prob. 25QPCh. 20 - Prob. 26QPCh. 20 - Prob. 27QPCh. 20 - Prob. 28QPCh. 20 - Prob. 29QPCh. 20 - Prob. 30QPCh. 20 - Prob. 31QPCh. 20 - Prob. 32QPCh. 20 - Prob. 33QPCh. 20 - Prob. 34QPCh. 20 - Prob. 35QPCh. 20 - Prob. 36QPCh. 20 - Prob. 37QPCh. 20 - Prob. 38QPCh. 20 - Prob. 39QPCh. 20 - Prob. 40QPCh. 20 - Prob. 41QPCh. 20 - Prob. 42QPCh. 20 - Prob. 43QPCh. 20 - Prob. 44QPCh. 20 - Prob. 45QP
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- The evidence leads modern astronomers to conclude that at the cores of active galaxies are supermassive black holes with masses as high as a. ten solar masses. b. a thousand solar masses. c. a million solar masses. d. a billion solar masses.arrow_forwardWhat objects did Harlow Shapley use to figure out the extent of the Milky Way Galaxy and the location of its center? A. thick clouds of cold hydrogen giving off 21-cm radiation B. globular clusters C. HIl regions D.dust clouds E. gamma-ray burstsarrow_forwardIf Hubble’s constant is taken to be 70 km/sec/Mpc, and a quasar is found with a radial velocity of 0.95 times the speed of light (3 × 10 5 km/s), how far away is the quasar? a. 4100 Mpc b. 0.014 Mpc c. 67 Mpc d. 74 Mpc e. 300,000 Mpcarrow_forward
- How do we know there are supermassive black holes driving active galaxies? a. The cores fluctuate over short periods of time, suggesting a small size. b. The gas near the core is moving very rapidly, suggesting high mass. c. The spectra are dominantly in the Balmer region, suggesting they are made of hydrogen. d. both a and b e. both a and carrow_forwardA stellar black hole may form when a massive star dies. The mass of the star collapses down to a single point. Imagine an astronaut orbiting a black hole having eight times the mass of the Sun. Assume the orbit is circular. a. Find the speed of the astronaut if his orbital radius is r = 1 AU. b. Find his speed if his orbital radius is r = 11.8 km. c. CHECK and THINK: Compare your answers to the speed of light in a vacuum. What would the astronauts orbital speed be if his orbital radius were smaller than 11.8 km?arrow_forwardConsider the following five kinds of objects: open cluster, giant molecular cloud, globular cluster, group of O and B stars, and planetary nebulae. A. Which occur only in spiral arms? B. Which occur only in the parts of the Galaxy other than the spiral arms? C. Which are thought to be very young? D. Which are thought to be very old? E. Which have the hottest stars?arrow_forward
- Assume that the Sun orbits the center of the Galaxy at a speed of 220 km/s and a distance of 26,000 lightyears from the center. A. Calculate the circumference of the Sun’s orbit, assuming it to be approximately circular. (Remember that the circumference of a circle is given by 2pR, where R is the radius of the circle. Be sure to use consistent units. The conversion from light-years to km/s can be found in an online calculator or appendix, or you can calculate it for yourself: the speed of light is 300,000 km/s, and you can determine the number of seconds in a year.) B. Calculate the Sun’s period, the “galactic year.” Again, be careful with the units. Does it agree with the number we gave above?arrow_forward3. Determine the Schwartzschild radius and the average density of a black hole formed by the gravitational collapse of a small galaxy of 10° solar masses. A solar mass is the mass of the Sun.arrow_forwardAstronomers now think that there is a black hole with more than 4 milliion times the mass of our Sun at the center of our galaxy? Roughly how large would the event horizon of such a supermassive black hole be? a. the size of our moon b. about 4 light years across c. about 17 times the size of our sun d. about the size of an atom (so much mass really compresses the event horizon) e. this question can't be answered without knowing what kind of stars were swallowed by the black holearrow_forward
- We know that dark matter must exist in galaxies. If not, many of the stars in a galaxy would ... a.Expand and go supernova due to the expansion of the Universe b.Fly away from the galaxy because the stars’ velocities are so large, and the galaxy would not have enough gravity to hold onto them c.Orbit the center of the galaxy normally d.Spiral in toward the center of the galaxy because most of the galaxy’s mass would be toward the centerarrow_forwardOur galaxy is suspected to be surrounded by a galactic corona because the disk of the galaxy a. rotates faster than expected in its outer region. b. rotates more slowly than expected in its outer region. c. rotates faster than expected in its inner region. d. rotates more slowly than expected in its inner region. e. is much flatter than expectedarrow_forwardWhich statement concerning black hole masses and Schwarzschild radii is not true? A. Even an object as small as you could become a black hole if there were some way to compress you to a size smaller than your Schwarzschild radius. B. The more massive the black hole, the larger the Schwarzschild radius. C. For black holes produced in massive star supernovae, Schwarzschild radii are typically a few to a few tens of kilometers. D. In a binary system with a black hole, the Schwarzschild radius depends on the distance from the black hole to the companion star.arrow_forward
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