What is at the very center of the Milky Way and what is the best evidence for it?
A: Only young, hot, massive stars- they've been detected in the IR
B: A cluster of neutron stars, 3 MS black holes- detected in the IR
C: A supermassive black hole- detections of stellar orbits over 8 years
D: Old stars, gas, dust, and giant molecular clouds- detected in the optical
E: Bok Globules, planetary nebulae, and brown dwarfs- detected with X-rays
Ans: C: A supermassive black hole- detections of stellar orbits over 8 years
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In the Drake equation, Nc = N* × fp × nHZ × fL × fI × fs, the factor Nc is:
A) the number of planets in a solar system. B) the average number of stars that have planets. C) the average number of planets in each solar system suitably placed in the habitable zone. D) the number of technological civilizations in the Milky Way Galaxy with which you might communicate.
In the above H-R diagram, which main sequence star is bluish in color?
A. A B. B C. C D. D E. E
Which statement below correctly describes the relationship between expansion rate and age for the universe?
A) The faster the rate of expansion, the younger the age of the universe. B) The faster the rate of expansion, the older the age of the universe. C) Age is independent of the expansion rate.
Measured ages of globular clusters suggests that the Universe is about
a. 1.4 billion years old. b. 14 billion years old. c. 140 billion years old.