1. Temperature: This determines the star's color and spectral type. Hotter stars are blue, while cooler stars are red. This is measured in Kelvin.

2. Luminosity: This refers to the total amount of energy a star emits per second. It's related to a star's size and temperature. Luminosity is often measured in units of solar luminosity (L_☉).

These two properties, along with others like mass, radius, and composition, help astronomers understand a star's evolution and its place in the universe.