Of what is the galactic halo presumed to be composed? What evidence supports this conclusion?
What will be an ideal response?
The globular clusters are most obvious, but it also has many loose stars of Population II, escaped from their clusters, and a great deal of dark matter, whose true nature is still uncertain; brown dwarfs, black holes, and white dwarfs are all possible candidates.
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A quasar's spectrum is hugely redshifted. What does this large redshift tells us about the quasar?
A) the composition of the quasar B) the distance to the quasar C) the mass of the quasar's central, supermassive black hole D) the type of host galaxy in which the quasar resides
An astronaut has landed on an asteroid and conducts an experiment to determine the free fall acceleration on that asteroid
He uses a simple pendulum that has a period of oscillation of 2.00 s on Earth and finds that on the asteroid the period is 11.3 s. What is the free fall acceleration on that asteroid? A) 0.307 m/s2 B) 1.66 m/s2 C) 1.74 m/s2 D) 5.51 m/s2 E) 0.0544 m/s2
It is believed that ring galaxies form
a. when two galaxies collide at high speeds. b. when two spiral galaxies collide, but not directly head on. c. from a large cloud of gas and dust with very little angular momentum. d. from a large cloud of gas and dust with a very high angular momentum. e. when more than two galaxies collide at the same time.
A 10-V battery is connected to a 15-? resistor and an unknown resistor R, as shown. The current in the circuit is 0.40 A. How much heat is produced in the 15-? resistor in 2.0 min?
A. 0.40 kJ B. 0.19 kJ C. 0.29 kJ D. 0.72 kJ E. 0.80 kJ