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Multiple Choice Quiz


Which of the following is a good description of Seyfert galaxy?
A)a spiral with a small bright nucleus
B)a dwarf elliptical
C)a tidally distorted irregular galaxy
D)a galaxy which has just merged with another galaxy

The radio emission from radio galaxies and quasars is due to
A)thermal emission
B)blackbody radiation
C)O and B stars
D)synchrotron radiation

For a typical luminous radio galaxy, the radio emission comes primarily from
A)the central few hundred parsecs of the galaxy
B)a large halo with a radius of about ten kiloparsecs
C)the disk, where most of the stars are concentrated
D)two large regions tens of kiloparsecs from the center of the galaxy

How do we know that the quasars are at large distances?
A)they are extremely dim
B)they have large redshifts
C)they have large parallaxes
D)they are greatly obscured by interstellar dust

Quasars were originally discovered as
A)strong radio sources identified with star-like images on photographs
B)variable sources of light
C)bright galaxies, and only later found to be radio sources
D)the only type of radio source within our galaxy

How do we know that quasars are no larger than the solar system?
A)they vary in brightness on a timescale of days or weeks
B)they appear point-like when viewed through a telescope
C)they contain black holes, which must be small
D)they are too luminous to be very large

About how large is a 100 million solar mass black hole such as those that may account for the energy output of quasars?
A)as large as a city
B)as large as the earth
C)a few AU across
D)a few light years across

How do astronomers explain the "superluminal'" motions observed in quasars?
A)an illusion produced when something moves rapidly almost straight at us
B)no trick, things really do move faster than the speed of light
C)the black holes in quasars cause a distortion in the rate of passage of time
D)quasars are contracting at almost the speed of light

Quasars all have great distances. Why are there no nearby quasars?
A)no quasars have existed in the recent past
B)quasars avoid spiral galaxies
C)quasars are found only in clusters of galaxies
D)if quasars are too close to us, they look like pulsars

Absorption lines in quasars are usually at lower redshifts. They are likely caused by
A)black holes at the center of quasars
B)intervening matter between the quasar and the observer
C)clouds of hydrogen in the back of the quasar
D)new galaxies surrounding the quasar

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