Star mass

The mass of a star is the total amount of matter it contains. It is one of the most important properties of a star, as it determines almost everything about how the star lives, changes, and dies. In astronomy, star mass is usually measured in solar masses (M☉) — where 1 solar mass is equal to the mass of our Sun.

Astronomers estimate a star’s mass in different ways. For stars in binary systems, they can use the gravitational interaction between the two stars to calculate their masses. For other stars, mass is often estimated based on temperature, brightness, and how the star fits into models of stellar structure and evolution.

Mass has a major effect on a star’s behavior. Massive stars burn their fuel faster and shine much brighter, but they also have shorter lifespans. Smaller stars like red dwarfs use energy slowly and can live for billions of years. As stars evolve, their mass and density can create more extreme objects. If the remaining mass after a star dies is high enough, it may collapse into a neutron star or even a black hole — an object with gravity so strong that not even light can escape.

In the Stellar Catalog, star masses are shown in solar masses to help compare stars directly to the Sun.