The temperature and brightness of stars are shown on the _________

Question

anonymous · Answer

Hi, @whitneyhicks221  Welcome to Open Study!! I would be glad to help you!!!

anonymous · Answer

It is complicated, but you already knew that, I bet. 

Brightness, or luminosity, is related to temperature, but it is also related to size, to the surface area of the star. Consider Betelgeuse, the second brightest star in Orion, and the ninth brightest in the sky. This star has a temperature about half the temperature of the sun (3500 degrees vs about 6000 degrees); *BUT* it is 135,000 times brighter than the sun! Why? because it has an enormous surface area: its radius is about 1000 times that of the sun. 

Now, consider a white dwarf star. Such stars are exceedingly hot. Consider 40 Eridani B. This white dwarf has a luminosity only 0.013 of the sun, but its temperature is over 16,000 degrees, almost 3 times as hot as the sun. Why is it so dim if it is so hot? Because it has a radius of only 0.014 of the sun. It is tiny in comparison. 

So, in general, of stars that are the *same* size the hotter will be the brighter. However, if the stars are not the same size, then the larger can be brighter.