Xi Tauri (ξ Tau, ξ Tauri) is a hierarchical quadruple system in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Taurus Taurus is Latin for 'bull' and may refer to: * Taurus (astrology), the astrological sign * Taurus (constellation), one of the constellations of the zodiac * Taurus (mythology), one of two Greek mythological characters named Taurus * ''Bos taurus ...

. Xi Tauri is a

spectroscopic Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wav ...

and eclipsing quadruple star. It consists of three blue-white B-type

main sequence star Main may refer to: Geography * Main River (disambiguation) **Most commonly the Main (river) in Germany *Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries * ...

s and an F-type main sequence star. Two of the stars form an

eclipsing binary A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

system and revolve around each other once every 7.15 days. These in turn orbit the third star once every 145 days. The fourth star is a F star that orbits the other three stars in a roughly fifty-year period and has been resolved optically. The brightest and most massive of the four stars is the "third" star, although the eclipsing pair have a greater combined mass and hence are generally considered to be the primary. The typical combined

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

of the system is +3.73, but because the stars eclipse one another during their orbits, it is classified as a

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

, and its brightness varies from magnitude +3.73 to +3.81. Xi Tauri is approximately 210

light years A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. Nomenclature for the four stars varies. Some sources refer to the faint resolved companion as component C, while others refer to it as B. Similarly, the inner three stars are respectively Aa, Ab, and B, or Aa, Ab, and Ac.

References

{{DEFAULTSORT:Xi Tauri Astrometric binaries Eclipsing binaries Spectroscopic binaries Tauri, Xi Taurus (constellation) 4 B-type main-sequence stars Tauri, 002 016083

1038 Year 1038 ( MXXXVIII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. Events By place Europe * Emperor Conrad II (the Elder) travels to Southern Italy and holds court in Troia. He orde ...

021364 Durchmusterung objects