Question

Describe the size, brightness, temperature of a Neutron star/ Protostar:

Answer 1

Neutron star: a newly formed neutron star can have a temperature of about 10^11 Kelvin to 10^12 Kelvin, but it can drop to 10^6 Kelvin. Its brightness is a million times fainter than the sun's brightness because of its size and distance from a point of view.

Dwarf star: Yellow dwarfs are small, main sequence star. Red dwarfs are the most common type of star, it's a small, cool, very faint, main sequence star whose surface temperature is under about 4,000 K.

Main sequence: has a temperature of about 10 million K. Its luminosity depends on the size and the mass of the star.

Red Giant: not normally as bright as the main sequence but it can create 1,000 to 10,000 times the luminosity that the sun gives off. The outer atmosphere is inflated, making the surface temperature to be as low as 5,000 K.
 
Supergiant: These stars have very "cool" surface temperatures that can range between 3500 and 4500 K (more or less). Depending on proximity, size, and mass, their luminosity can be either very high or very dim... though, they are normally very large stars.

Hope this helped!