Based on their shapes and stars, elliptical galaxies are most like the Milky Way’sthe Magellanic Clouds... Based on their shapes and stars, elliptical galaxies are most like the Milky Wa
Trang 1TO THE UNIVERSE
EIGHTH EDITION
CHAPTER 15 Normal and Active Galaxies
Clickers
Trang 2Based on their shapes and stars, elliptical galaxies are most like the Milky Way’s
the Magellanic Clouds
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Trang 3Based on their shapes and stars, elliptical galaxies are most like the Milky Way’s
b) halo.
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
Trang 4What property is shared by spiral galaxies?
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Trang 5What property is shared by spiral galaxies?
e) All of the above
Explanation: M-51, a Type Sb spiral
Trang 6The Magellanic Clouds are
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Trang 7The Magellanic Clouds are
b) small irregular galaxies that orbit the Milky Way.
Trang 8Hubble took spectra of galaxies in the 1930s What did
he find?
redshifts and half blueshifts
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Trang 9Hubble took spectra of galaxies in the 1930s What did
he find?
a) Most galaxies showed redshifts.
redshifts and half blueshifts
that changed into a blueshift atother times
Explanation: Redshifts of galaxies indicate
they are moving away from us
Trang 10Hubble’s law is based on
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Trang 11Hubble’s law is based on
c) more distant galaxies showing greater redshifts.
variables appearing brighter
appearing younger
Trang 12Hubble’s constant measures the
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Trang 13Hubble’s constant measures the
e) 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
velocity = H0 x distance
Trang 14To calibrate Hubble’s constant, astronomers must determine
Trang 15To calibrate Hubble’s constant, astronomers must determine
Trang 16Hubble’s discovery of galaxy redshifts means
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Trang 17Hubble’s discovery of galaxy redshifts means
c) the universe is expanding.
Trang 18Quasars are “quasi-stellar” because
through H to He fusion like stars
extremely bright O stars
eclipsing binary stars
their images appear stellar
of millions of stars
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Trang 19Quasars are “quasi-stellar” because
through H to He fusion like stars
extremely bright O stars
eclipsing binary stars
d) in short-exposure photographs,
their images appear stellar.
of millions of stars
Explanation: Although short-exposure images can appear starlike, many quasars show jets or other signs of intense activity
Trang 20Seyfert and radio galaxies could be powered by
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Trang 21Seyfert and radio galaxies could be powered by
a) supermassive black holes at their cores.
Explanation: The Circinus Galaxy,
a Seyfert galaxy about 4 Mpc away
Trang 22In active galaxies, the central engine can be “fed” by
formation
in the core
a larger black hole
nearby galaxy
and emitting light
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Trang 23In active galaxies, the central engine can be “fed” by
formation
in the core
a larger black hole
d) close encounters with a
nearby galaxy.
and emitting light