You obtain a spectrum of an object in space. The spectrum consists of a number of sharp, bright emission lines. Is this object a cloud of hot gas, a cloud of cool gas, or a star?

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?