If neutron stars contain no nuclear fuel, why are they hot? ...

[123654777]

If neutron stars contain no nuclear fuel, why are they hot?
 
  What will be an ideal response?

Question 2

The parallax angle of the Sun is 1 arc second.
 
  a. True
  b. False
  Indicate whether the statement is true or false

[Pswine]

Answer to Question 1

Contraction heats the gas in a star. As gas particles fall inward, they pick up speed, and when they collide, their high speeds become thermal energy. The sudden collapse of the core of a massive star to a radius of 10 km should heat it to a trillion degrees. Astronomers calculate that neutron stars should initially cool rapidly from that high temperature because neutrinos can escape from their entire volume and carry energy away. After a few years neutron stars will cool down to a million degrees or so, and neutrinos won't be produced in bulk. From that point on, neutron stars should cool slowly because the heat can escape only from the surface, and neutron stars are so small they have little surface from which to radiate.

Answer to Question 2

False
RATIONALE: For p = 1, d = 1 pc and the Sun is not at 1 pc.

[123654777]

Thanks for the timely response, appreciate it

[gcook]

Gracias!