Binärsterne

Binärsterne, also known as binary stars, are systems of two stars orbiting a common center of mass. They are the most common type of star system in the Milky Way galaxy, with estimates suggesting that over half of all stars exist in binary or multiple star configurations. Observing binary stars is crucial for understanding stellar masses, as their orbital motion directly reveals the gravitational influence of each star. This allows astronomers to apply Kepler's laws of planetary motion to determine the masses of the stars, a feat not possible with isolated stars.

Binary stars are classified based on how they are detected. Visual binaries are systems where both stars can be seen as separate objects through a telescope, allowing direct observation of their orbits. Spectroscopic binaries are detected by analyzing the Doppler shift in their light. As the stars orbit, their light shifts towards blue when approaching and towards red when receding, revealing their orbital velocities and thus their masses and orbital periods. Eclipsing binaries are detected when one star passes in front of the other from our perspective, causing a periodic dip in the system's brightness. These systems are particularly valuable for determining the radii and luminosities of the stars. Astrometric binaries are identified by the slight wobble in the apparent position of one star, caused by the gravitational tug of an unseen companion.

The study of binary stars has provided invaluable insights into stellar evolution, the formation of planetary systems, and the fundamental laws of physics, including gravity.