•Question 3 (1
point) Assume that relatively young white dwarfs and neutron stars have similar
temperatures (both very
hot, although cooling at different rates). White dwarfs are hard to spot because the radiating surface is small (about
the size of Earth).
Neutron stars are even smaller (for this questions assume 10 km radius). How much fainter are they?
•a.About 4 million times fainter.
•b.About
400000 times fainter.
•c.About 40000 times fainter.
•d.About 4000 times fainter.
•e.about 400 times fainter.
•
•We know
that the luminosity of a star depends on its temperature to the 4th power times a constant times its surface
area. If temperature is the same, this question
really boils down to the relative surface areas.
Ballpark, a neutron star has a radius = 10km, while a white dwarf is about the size
of the Earth (radius = 6378 km). Surface area
depends on the radius squared. Squaring
6378/10
gives about 400,000.