Question 3 (1 point) Quasars can be 1000
times more luminous than
a galaxy. The absolute magnitude of such a luminous quasar would be about M = -28.5. If the black hole in the
center of our galaxy
became a quasar, what would the apparent magnitude of the galactic core be?
a. -13.9 b.19 c. 0 d.-4.6 e.8.5
We need to use the
equation: m – M = -5 + 5 log d(pc)
d
= 8500 pc, M = -28.5, so: m + 28.5 = -5 + 19.6
m
= -13.9
Question
4 (1 point) A quasar is observed to have a redshift z=0.5. What recessional velocity does this correspond
to?
a. 4% of the speed
of light. b. 38% of
the speed of light. c. 50% of
the speed of light.
d. 77% of the speed of light. e. 99% of the speed of light.
v/c = ((z+1)2-1)/((z+1)2+1) = (2.25-1)/(2.25+1) = (1.25)/(3.25) = 0.38