description Xi Ursae Majoris Overview
Xi Ursae Majoris (also named Alula Australis) is a quadruple star system located approximately 27 to 29 light-years from Earth in the constellation Ursa Major. It holds the historical distinction of being the first binary star to have its orbit calculated, accomplished by French astronomer Félix Savary in 1828. The system consists of two orbiting pairs, with the primary components being Sun-like F- and G-type main sequence stars. The system is faintly visible to the naked eye under good conditions at approximately magnitude 4.
insights Ranking position
Xi Ursae Majoris ranks #64 of 212 in the Star ranking, behind Shaula, ahead of Gacrux.
help Xi Ursae Majoris FAQ
Why was Xi Ursae Majoris important in the history of astronomy?
Xi Ursae Majoris became the first visual binary whose orbit was successfully calculated. Félix Savary published that orbital calculation in 1828 using observations of the pair's changing position.
Is Xi Ursae Majoris one star, a binary, or a quadruple system?
It is a hierarchical quadruple system made from two close binary pairs. The two brighter visual components are commonly designated Xi Ursae Majoris A and B, but each has a lower-mass companion.
Can Xi Ursae Majoris be seen without a telescope?
The combined system is bright enough to be visible to the unaided eye under suitable skies in Ursa Major. Resolving its principal components requires a telescope because they appear as a single point to ordinary vision.
How far away is Xi Ursae Majoris?
Xi Ursae Majoris lies roughly 27 light-years from the Solar System. This relative proximity helped astronomers follow the visual pair's motion over time.
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