Astronomy Chapter 14 Answers – Flashcards
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A particular galaxy contains only stars in disordered orbits. This type of galaxy is most likely
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an elliptical
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If the universe were not expanding, the relationship between the velocity of a galaxy and its distance (as in the Hubble law plot) would
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be horizontal
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In every direction that astronomers look, they see the same Hubble law, with the same slope. This is an example of
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isotropy
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In spiral galaxies, stars form predominantly in
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the arms of the disk
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Supermassive black holes occur
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in most, perhaps all, large galaxies
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What do Supermassive black holes do
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are "fed" by disturbed gas when galaxies interact
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The light that comes to us from active galactic nuclei comes from a volume about the size of
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The Solar System
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The rotation curves of galaxies tell us that galaxies are mostly
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Dark Matter
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Which of the following are properties of dark matter? (Select all that apply.) It absorbs all the light that falls on it. It reflects all the light that falls on it. It doesn't interact with light, as far as we can tell. It gravitationally attracts other matter. It gravitationally repels other matter. It doesn't interact gravitationally, as far as we can tell.
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It reflects all the light that falls on it. It doesn't interact with light, as far as we can tell.
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An elliptical galaxy may appear round if (choose all that apply) all three axes are the same; it is spherical in shape. it is elongated along one axis; but it is viewed parallel to the long axis. it has one axis shorter than the other two; but it is viewed parallel to the short axis. all three axes are different lengths; but it is viewed from a special angle.
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all three axes are the same; it is spherical in shape. it is elongated along one axis; but it is viewed parallel to the long axis. it has one axis shorter than the other two; but it is viewed parallel to the short axis.
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When viewed "edge-on," a spiral galaxy often
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has a dark lane across the middle.
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Observation of spectra from distant galaxies suggests that
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distant galaxies are moving away from us.
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On the average, dark matter
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accounts for 95% of the total mass of a spiral galaxy.
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Spiral density waves in galaxies are responsible for
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promoting star formation.
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The implication of Hubble's law is that
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space itself is expanding.
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The observed speed of material orbiting in a galaxy
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is almost constant for all material far from the center.
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The outer parts of spiral galaxies are
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mostly dark matter.
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The spectra of distant galaxies have what feature?
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They show Doppler shifts toward longer wavelengths.
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What extraordinary feature is common among active galactic nuclei?
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very high luminosity
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According to Hubble's law, a galaxy's
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velocity away from us gets greater as its distance away from us increases.
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Assuming galaxies A and B are distant, if galaxy A has a redshift of z = 0.2 and galaxy B has a redshift of z = 0.6,
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galaxy A is closer to us than galaxy B, and galaxy B is moving away from us at the greater speed.
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At the center of an active galactic nucleus
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is a supermassive black hole with an accretion disk.
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Besides shape, spiral and elliptical galaxies differ in
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composition and temperature of their gases.
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Dark matter is most likely composed of
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weakly interacting massive elementary particles.
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Dark matter is not like "normal" matter because
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it doesn't emit any radiation.
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Elliptical galaxies
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Are spherical or oval
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For the universe to be homogeneous, it must
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have the same properties in all locations.
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For the universe to be isotropic, it must
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look the same as view from all directions
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Hubble's tuning fork classification separates what kinds of galaxies?
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spiral and elliptical
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Irregular galaxies are
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not on the Hubble tuning fork and have no particular shape
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Quasars are
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both distant and highly luminous objects
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S0 galaxies are
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disk-like with no spiral arms
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Spiral arms are more prominent in UV light than visible light because
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more massive, young stars are found in the spiral arms.
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Spiral structure of a galaxy tends to form because
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it takes less time for the center of a galaxy to rotate than its outside
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Star birth most actively takes place
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in spiral arms of galaxies.
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The physical laws of the universe
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should be the same everywhere.
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The shape of an elliptical galaxy is
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due to the nearly random orbits of stars around the galactic center.
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To directly measure a distance to a very distant galaxy, the standard candle you would be most likely to use is
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a Type I supernova.
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To measure a galaxy's total mass, one needs to analyze
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the gravitational effects of the galaxy.
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We know that active galactic nuclei are small because
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they can vary drastically in luminosity in a couple of days.
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With a great deal of star birth taking place in spiral arms, we should also expect the spiral arms to contain
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large concentrations of dense clouds.
