___________ is (are) observed when light from a distant quasar travels past a massive galaxy between us and the quasar, and this light is focused to form two or more images of the same quasar.
a. A double-lobed radio galaxy
b. Superluminal expansion
c. The gravitational lens effect
d. A blazar
e. Gravitational waves
Question 2If the stars at the turnoff point of a cluster have a mass of 3M, what is the age of the cluster?
a. 3.01010 years
b. 3.3109 years
c. 6.4108 years
d. 1.61011 years
e. The age of a star cluster cannot be determined from the mass of stars at the turnoff point.
Question 3According to the unified model of active galactic nuclei, ___________ is in the center surrounded by _____________with a Type 1 Seyfert or Type 2 Seyfert being seen depending on the viewing angle.
a. a supermassive black hole; an accretion disk
b. a supermassive black hole; empty space
c. no black hole; an accretion disk
d. no black hole; empty space
Question 4Stars in a star cluster
a. all have the same age.
b. all have the same chemical composition.
c. all have the same luminosity.
d. all of the above.
e. all have the same age and all have the same chemical composition.
Question 5What was the first evidence that quasars were different from astronomical objects before they were observed in visual wavelengths?
a. The first quasars were seen to have fuzz.
b. Quasars emitted radio energy like active galaxies, but appeared to be point sources in radio wavelengths.
c. Quasars showed significant gravitational lens effects.
d. The spectra of quasars looked like that of an M dwarf.
e. The larger redshifts originally indicated that they were orbiting the center of the Milky Way.
Question 6Helium flash occurs
a. because helium is very explosive and cannot be controlled when the nuclear reactions occur.
b. because degenerate gas does not allow the core to expand as it heats up.
c. in Cepheid variables.
d. in stars with masses less than 0.4 M.
e. None of the other choices are correct.
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