Kaksiktähtede

Kaksiktähtede is an Estonian term that translates to "binary stars" or "double stars" in English. This astronomical term refers to two stars that are gravitationally bound to each other and orbit a common center of mass. These systems are incredibly common in the universe, with estimates suggesting that more than half of all stars in the Milky Way galaxy exist as binary or multiple star systems.

The study of binary stars is crucial for understanding stellar evolution and determining stellar masses. By observing the orbital period and the separation between the stars, astronomers can apply Kepler's laws of planetary motion and Newton's law of universal gravitation to calculate the masses of the individual stars. This is a fundamental method, as directly measuring the mass of a single star is exceptionally difficult.

Binary stars can be classified based on how they are detected. Visual binaries are those where both stars can be resolved with a telescope. Spectroscopic binaries are detected by observing the Doppler shift in their spectral lines, indicating that they are moving towards or away from us as they orbit. Eclipsing binaries are systems where the orbital plane is such that one star periodically passes in front of the other from our perspective, causing a dip in the total observed brightness. Astrometric binaries are detected by observing the "wobble" of a visible star caused by the gravitational pull of an unseen companion.

The variety of binary star systems, from closely packed pairs to widely separated ones, and the different ways they interact, provide astronomers with a rich source of data to explore the complex processes that govern the lives of stars.