Upsilon Orionis (υ Ori, υ Orionis) is a star in the constellation Orion. It has the traditional name ''Thabit'' or '' Tabit'' (ﺛﺎﺑﺖ,

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ...

for "the endurer"), a name shared with pi3 Orionis. It is a blue-white main sequence star of

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 ...

4.62 located over 3000 light-years distant from the

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

. It is a suspected

Beta Cephei variable Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200, ...

Name

Located south of Iota Orionis, Upsilon Orionis is one of two stars (the other is 29 Orionis) marking the top of Orion's right boot in Johann Bayer's ''

Uranometria ''Uranometria'' is a star atlas produced by Johann Bayer. It was published in Augsburg in 1603 by Christoph Mangle (''Christophorus Mangus'') under the full title ''Uranometria: omnium asterismorum continens schemata, nova methodo delineata, a ...

'' (1603). It was given the number 36 by

John Flamsteed John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called '' Atlas C ...

, while its proper name appears to be derived from the Arabic ''Al Thabit'' "the endurer". In his '' Star-Names and Their Meanings'' (1899), American amateur naturalist

Richard Hinckley Allen In astronomy, stars have a variety of different stellar designations and names, including catalogue designations, current and historical proper names, and foreign language names. Only a tiny minority of known stars have proper names; all others ha ...

noted that the name appeared on the star atlas ''Geography of the Heavens'', composed by Elijah Hinsdale Burritt, but its ultimate origin was unknown.

Properties

Since 1943, this star has been consistently defined as a B0 main sequence star used as a reference for classifying the spectra of other stars on the MK scale, although in other studies it has been classified as O9V and O9.5V. The Galactic O-Star Spectroscopic Survey has defined it as the standard star for the O9.7 V spectral type. In a 1981 paper, υ Orionis was observed to have nonradial pulsations over a period of around 12 hours, and has been classified as a slowly pulsating B star. Subsequent review of Hipparcos catalog data indicated it was most likely a

, and is hence considered a candidate for that class. These are blue-white main sequence stars of around 10 to 20 times the mass of the Sun that pulsate with periods of 0.1 to 0.3 days; their changes in magnitude are much more pronounced in the ultraviolet than in the visual spectrum. It is classified as a Beta Cephei variable by the

American Association of Variable Star Observers The American Association of Variable Star Observers (AAVSO) is an international nonprofit organization, founded in 1911, focused on coordinating, analyzing, publishing, and archiving variable star observations made largely by amateur astronomers. ...

, and has an

of +4.62. υ Orionis's parallax has been measured at , yielding a distance of approximately 2,900 light years 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 ...

. A 1979 review of photometry of O and B stars found it to be around 1666 light-years distant, with a radius 7.5 times and luminosity 44,000 times that of the Sun, and surface temperature of 33,000 K. and a mass 16.6 times that of the Sun. It is one of the most massive stars of the Orion OB1c association (in Orion's Sword).

References

{{DEFAULTSORT:Upsilon Orionis Orion (constellation) Orionis, Upsilon Thabit Beta Cephei variables Orionis, 36 025923 O-type main-sequence stars

1855 Events January–March * January 1 – Ottawa, Ontario, is incorporated as a city. * January 5 – Ramón Castilla begins his third term as President of Peru. * January 23 ** The first bridge over the Mississippi River open ...

036512 Durchmusterung objects