1. a) Express the distance of the star Proxima Centauri from the star Sirius B and the planet
Earth in light years.

1. d) The average temperature of the interior of a sun-like star is of the order 10^8 K. Estimate
the mass of the star in terms of the solar mass if it has a radius of order 10^10 cm.

3. b) A supernova explosion takes place at the distance of 4 pc. If the absolute magnitude of
the supernova is −25, calculate its apparent magnitude. Will the supernova be brighter
than the Sun? Justify your answer.