Which stellar spectral type has strong molecular absorption lines in its optical spectrum?
A) M B) G C) K D) O E) B
A
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The gravitational force exerted by the Earth on the Moon holds the moon in an orbit around the Earth. Let us assume that the orbit is perfectly circular. The work done by this gravitational force during a one week interval in which the moon moves through a displacement in its orbital path is
1.negative. 2.zero. 3.positive. 4.impossible to determine with the information given.
What do halo stars do differently from disk stars?
A) They orbit the galactic center with many different inclinations, while disk stars all orbit in nearly the same plane. B) Halo stars explode as supernovae much more frequently than disk stars. C) They remain stationary, quite unlike disk stars that orbit the galactic center. D) They orbit the center of the galaxy at much lower speeds than disk star.
Charon is a moon of ______________
a. Earth b. Venus c. Neptune d. Mars e. Pluto
Why are stars no longer forming in the galactic halo?
A) Frequent supernovae blew all the halo gas out into intergalactic space. B) There was never star formation in the halo; its stars were ejected from the disk. C) Only low-mass stars formed in the halo, so there were no stellar winds or supernovae to recycle gas. D) The cold molecular gas required for star formation is in the galactic disk.