Astronomy A BEGINNER’S GUIDE TO THE UNIVERSE EIGHTH EDITION CHAPTER 15 Normal and Active Galaxies Clickers © 2017 Pearson Education, Inc Question Based on their shapes and stars, elliptical galaxies are most like the Milky Way’s a) b) c) d) e) disk and spiral arms halo central bulge open clusters companion galaxies, the Magellanic Clouds © 2017 Pearson Education, Inc Question Based on their shapes and stars, elliptical galaxies are most like the Milky Way’s a) b) c) d) e) disk and spiral arms halo central bulge open clusters companion galaxies, the Magellanic Clouds Explanation: Like the stars and globular clusters in our halo, elliptical galaxies contain little or no gas and dust to make new stars © 2017 Pearson Education, Inc Question What property is shared by spiral galaxies? a) b) c) d) e) © 2017 Pearson Education, Inc Ongoing star formation A disk, bulge, and halo Globular clusters in the halo Open clusters in the disk All of the above Question What property is shared by spiral galaxies? a) b) c) d) e) Ongoing star formation A disk, bulge, and halo Globular clusters in the halo Open clusters in the disk All of the above Explanation: M-51, a Type Sb spiral © 2017 Pearson Education, Inc Question The Magellanic Clouds are a) b) c) d) e) © 2017 Pearson Education, Inc giant globular clusters in the halo small irregular galaxies that orbit the Milky Way large molecular clouds in the disk of our Galaxy the brightest ionized hydrogen regions in our Galaxy spiral nebulae originally discovered by Herschel Question The Magellanic Clouds are a) b) c) d) e) © 2017 Pearson Education, Inc giant globular clusters in the halo small irregular galaxies that orbit the Milky Way large molecular clouds in the disk of our Galaxy the brightest ionized hydrogen regions in our Galaxy spiral nebulae originally discovered by Herschel Question Hubble took spectra of galaxies in the 1930s What did he find? a) b) c) Most galaxies showed redshifts All galaxies showed blueshifts Galaxies showed about half redshifts and half blueshifts d) e) © 2017 Pearson Education, Inc Galaxies showed no line shifts at all Some galaxies showed a redshift that changed into a blueshift at other times Question Hubble took spectra of galaxies in the 1930s What did he find? a) b) c) Most galaxies showed redshifts All galaxies showed blueshifts Galaxies showed about half redshifts and half blueshifts d) e) Galaxies showed no line shifts at all Some galaxies showed a redshift that changed into a blueshift at other times Explanation: Redshifts of galaxies indicate they are moving away from us © 2017 Pearson Education, Inc Question Hubble’s law is based on a) b) c) d) e) © 2017 Pearson Education, Inc more distant galaxies showing greater blueshifts distant quasars appearing proportionally dimmer more distant galaxies showing greater redshifts slowly varying Cepheid variables appearing brighter more distant galaxies appearing younger Question Hubble’s law is based on a) b) c) d) more distant galaxies showing greater blueshifts distant quasars appearing proportionally dimmer more distant galaxies showing greater redshifts slowly varying Cepheid variables appearing brighter e) more distant galaxies appearing younger © 2017 Pearson Education, Inc Question Hubble’s constant measures the a) b) c) d) e) © 2017 Pearson Education, Inc density of galaxies in the universe luminosity of distant galaxies reddening of light from dust clouds speed of a galaxy rate of expansion of the universe Question Hubble’s constant measures the a) b) c) d) e) density of galaxies in the universe luminosity of distant galaxies reddening of light from dust clouds speed of a galaxy rate of expansion of the universe Explanation: Hubble’s law relates how fast galaxies are moving away from us at different distances A larger value for H0 implies a faster expansion rate © 2017 Pearson Education, Inc velocity = H0 x distance Question To calibrate Hubble’s constant, astronomers must determine a) b) c) the size of the universe distances to galaxies the speed of recession of galaxies d) the density of matter in the universe e) the temperature of the Big Bang © 2017 Pearson Education, Inc Question To calibrate Hubble’s constant, astronomers must determine a) b) c) the size of the universe distances to galaxies the speed of recession of galaxies d) the density of matter in the universe e) the temperature of the Big Bang Explanation: Distances to galaxies are determined using a variety of “standard candles,” including Cepheid variables, supernova explosions, model galaxies, and model clusters © 2017 Pearson Education, Inc Question Hubble’s discovery of galaxy redshifts means a) b) c) d) e) © 2017 Pearson Education, Inc the universe is static the universe is collapsing the universe is expanding the Milky Way is the center of the universe There is no accepted interpretation Question Hubble’s discovery of galaxy redshifts means a) b) c) d) e) © 2017 Pearson Education, Inc the universe is static the universe is collapsing the universe is expanding the Milky Way is the center of the universe There is no accepted interpretation Question Quasars are “quasi-stellar” because a) they generate energy partly through H to He fusion like stars b) they show spectra similar to extremely bright O stars c) their luminosity varies like eclipsing binary stars d) in short-exposure photographs, their images appear stellar e) they are dense concentrations of millions of stars © 2017 Pearson Education, Inc Question Quasars are “quasi-stellar” because a) they generate energy partly through H to He fusion like stars b) they show spectra similar to extremely bright O stars c) their luminosity varies like eclipsing binary stars d) in short-exposure photographs, their images appear stellar e) they are dense concentrations of millions of stars Explanation: Although short-exposure images can appear starlike, many quasars show jets or other signs of intense activity © 2017 Pearson Education, Inc Question 10 Seyfert and radio galaxies could be powered by a) b) c) d) e) © 2017 Pearson Education, Inc supermassive black holes at their cores dark matter self-sustaining star formation spiral density waves hypernova explosions Question 10 Seyfert and radio galaxies could be powered by a) b) c) d) e) supermassive black holes at their cores dark matter self-sustaining star formation spiral density waves hypernova explosions Explanation: The Circinus Galaxy, a Seyfert galaxy about Mpc away © 2017 Pearson Education, Inc Question 11 In active galaxies, the central engine can be “fed” by a) sudden bursts of star formation b) supernova chain reactions in the core c) the collapse of the core into a larger black hole d) close encounters with a nearby galaxy e) dark matter becoming visible and emitting light © 2017 Pearson Education, Inc Question 11 In active galaxies, the central engine can be “fed” by a) sudden bursts of star formation b) supernova chain reactions in the core c) the collapse of the core into a larger black hole d) close encounters with a nearby galaxy e) dark matter becoming visible and emitting light © 2017 Pearson Education, Inc ... c) the size of the universe distances to galaxies the speed of recession of galaxies d) the density of matter in the universe e) the temperature of the Big Bang Explanation: Distances to galaxies... companion galaxies, the Magellanic Clouds Explanation: Like the stars and globular clusters in our halo, elliptical galaxies contain little or no gas and dust to make new stars © 2017 Pearson Education,... galaxy rate of expansion of the universe Explanation: Hubble’s law relates how fast galaxies are moving away from us at different distances A larger value for H0 implies a faster expansion rate ©