By the amount of energy that they are giving out.
astronemers
How hot it is and how much it weighs.
an astronemer studys the earth, planets and stars
A star's color indicates its temperature. Hotter stars emit more blue light and appear blue or white, while cooler stars emit more red light and appear red or orange. By studying a star's color, astronomers can determine its temperature and infer other properties like its age and size.
Yes, a star is a glowing sphere of hot gas.
The blue star is the hottest star.
Hot Hot Hot
hot, bright star
It is a cool star.
Star colors tell us how hot the star is. For example a red colored star is cool and a blue colored star is hot.
There is no such thing as a star that is not hot.
it could be as hot as a star.