Epsilon Aurigae

Epsilon Aurigae is a multiple star system in the northern constellation of Auriga, the charioteer. Its name is a Bayer designation that is Latinized from ε Aurigae, and abbreviated Epsilon Aur or ε Aur. It is an unusual eclipsing binary system comprising an F0 supergiant and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a binary system of two dwarf B-type stars. The primary component is officially named Almaaz, pronounced /ælˈmɑːz/, the traditional name for the system. The distance to the system is still a subject of debate, but data from the Gaia spacecraft puts its distance at around 3,300 light years from Earth.

Epsilon Aurigae was first suspected to be a variable star when German astronomer Johann Heinrich Fritsch observed it in 1821. Later observations by Eduard Heis and Friedrich Wilhelm Argelander reinforced Fritsch's initial suspicions and attracted attention to the star. Hans Ludendorff, however, was the first to study it in great detail. His work revealed that the system was an eclipsing binary variable, a star that dims when its partner obscures its light.