Xi Ophiuchi

ξ Oph, <a href="/facts/Romanization_of_Greek/KTELT9Aq">Latinized</a> as Xi Ophiuchi, is a visual <a href="/facts/Binary_star/TYlDe1bD">binary star</a> system in the <a href="/facts/Celestial_equator/P9Lyq2DE">equatorial</a> <a href="/facts/Constellation/nBQqgW8A">constellation</a> of <a href="/facts/Ophiuchus_(constellation)/8hQ48ttM">Ophiuchus</a>. It has a yellow-white hue and is faintly visible to the naked eye with a combined <a href="/facts/Apparent_visual_magnitude/7pCTF1Me">apparent visual magnitude</a> of 4.39. The system is located approximately 57.1 <a href="/facts/Light-year/IGc5NdQb">light-years</a> (17.5 <a href="/facts/Parsec/SwSsk57J">parsecs</a>) away from the Sun based on <a href="/facts/Stellar_parallax/ywI9UWEJ">parallax</a>, but is drifting closer with a <a href="/facts/Radial_velocity/B3NmbVLP">radial velocity</a> of -9 km/s.
The magnitude 4.40 primary, designated component A, is an ordinary <a href="/facts/F-type_main-sequence_star/e8xcfI01">F-type main-sequence star</a> with a <a href="/facts/Stellar_classification/dYrIuK9H">stellar classification</a> of F2V. It is 916 million years old and is rotating with a <a href="/facts/Projected_rotational_velocity/N0VzIXLC">projected rotational velocity</a> of 20 km/s. The star has 1.3 times the <a href="/facts/Mass_of_the_Sun/j6Auhku8">mass of the Sun</a> and 1.6 times the <a href="/facts/Sun%2527s_radius/5t1Xavju">Sun's radius</a>. It is radiating 4.4 times the <a href="/facts/Luminosity_of_the_Sun/CLG0r9bP">luminosity of the Sun</a> from its <a href="/facts/Photosphere/32a139LB">photosphere</a> at an <a href="/facts/Effective_temperature/RY30DaSY">effective temperature</a> of 6,611 K.
The system is a source of <a href="/facts/X-ray_astronomy/KAQ6WxgQ">X-ray emission</a>. The orbiting companion, component B, is a magnitude 8.9 star at an <a href="/facts/Angular_separation/6ob2n0Wb">angular separation</a> of 4.1<a href="/facts/Second_of_arc/tybs6YGC">″</a> along a <a href="/facts/Position_angle/TXCTArC6">position angle</a> of 26° from the primary, as of 2016. A magnitude 10.8 <a href="/facts/Visual_companion/FLXY1tD1">visual companion</a>, component C, lies at a separation of 10.8″, as of 2004.
According to Richard H. Allen's <a href="/facts/Star_Names/353t0eky">Star Names</a>: Their Lore and Meaning (1899), ξ Oph together with <a href="/facts/Theta_Ophiuchi/NeCSs7y6">θ Oph</a> formed the <a href="/facts/Sogdia/I715sIoQ">Sogdian</a> Wajrik "the Magician", the Khorasmian Markhashik "the Serpent-bitten" and with <a href="/facts/Eta_Ophiuchi/mwpTDzjH">η Oph</a> the <a href="/facts/Coptic_language/EzDloWDH">Coptic</a> Tshiō, "the Snake", and Aggia, "the Magician". The name Aggia for this star appears in a 1971 NASA list of star names and in a 2023 list of target stars for the <a href="/facts/Habitable_Worlds_Observatory/6zdBtVm5">Habitable Worlds Observatory</a>. As of April 2025<a href="https://en.wikipedia.org/w/index.php?title=Xi_Ophiuchi&action=edit">[update]</a>, it does not appear in the <a href="/facts/IAU_Working_Group_on_Star_Names/EoRy108k">IAU Catalog of Star Names</a>.

Xi Ophiuchi open-in-new

Xi Ophiuchi