The first confirmed black hole, Cygnus X-1, was regarded as proof that black holes exist because it
a. is a compact object in a binary system
b. emits X-rays from a hot accretion disk
c. is accreting matter from a main-sequence companion
d. has a period of 5.6 days
e. has a mass of ten solar masses
e
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A white dwarf cools slowly into a _________________ dwarf
Fill in the blank(s) with correct word
For a galaxy to be active, the supermassive black hole needs to have matter flow into it
a. True b. False Indicate whether the statement is true or false
Gravitational Potential Energy: Three masses are located as follows: a 3.0-kg mass is at the origin, a 4.5-kg mass at (0.0 m, 4.0 m) and a 2.5-kg mass at (3.0 m, 0.0 m). What is the gravitational potential energy of this system of masses? (G = 6.67 × 10-11 N ? m2/kg2)
A. -3.8 × 10-10 J B. -3.9 × 10-10 J C. -5.4 × 10-10 J D. -3.2 × 10-10 J E. -3.5 × 10-10 J
Why isn't there a planet where the asteroid belt is located?
A) There was not enough material in this part of the solar nebula to form a planet. B) A planet once formed here, but it was broken apart by a catastrophic collision. C) Gravitational tugs from Jupiter prevented material from collecting together to form a planet. D) There was too much rocky material to form a terrestrial planet, but not enough gaseous material to form a jovian planet. E) The temperature in this portion of the solar nebula was just right to prevent rock from sticking together.