1. Temperature: This is directly related to the star's color. Hotter stars emit more blue light, while cooler stars emit more red light. Astronomers use a system called the spectral classification to categorize stars based on their temperature, ranging from the hottest (O) to the coolest (M).
2. Luminosity: This refers to the total amount of energy a star emits per second. Luminosity is related to a star's size and mass. The more massive and larger a star is, the more luminous it will be. Astronomers use a system called the Hertzsprung-Russell Diagram (H-R diagram) to plot stars based on their temperature and luminosity. This allows them to identify different stages of stellar evolution.
