Binary stars are a system of two stars that orbit around a common center of mass. They can be either physically connected or just gravitationally bound.
Apparent magnitudes of binary stars are measured by observing the brightness of the stars from Earth. This measurement is affected by factors such as distance, size, and brightness of the stars.
Apparent magnitude is the measure of a star's brightness as seen from Earth, while absolute magnitude is the measure of a star's brightness at a standard distance of 10 parsecs (about 32.6 light years) from Earth. Absolute magnitude takes into account the distance of the star, making it a more accurate measure of its true brightness.
Binary stars can affect each other's apparent magnitudes through eclipses, where one star blocks the light of the other, causing a decrease in apparent brightness. They can also affect each other through gravitational interactions, causing changes in their orbits and therefore changes in their apparent magnitudes.
Studying binary stars' apparent and absolute magnitudes can provide valuable information about their physical properties, such as mass and distance. It can also help astronomers understand the evolution of stars and the dynamics of their interactions in binary systems.