Located south of
Iota Orionis,[11] 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 (1603).[12] It was given the number 36 by
John Flamsteed, while its proper name appears to be derived from the Arabic Al Thabit "the endurer".[11] In his Star-Names and Their Meanings (1899), American amateur naturalist
Richard Hinckley Allen noted that the name appeared on the star atlas Geography of the Heavens, composed by Elijah Hinsdale Burritt, but its ultimate origin was unknown.[13]
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,[14] although in other studies it has been classified as O9V[15] and O9.5V.[16] The
Galactic O-Star Spectroscopic Survey defined it as the standard star for the O9.7V spectral type in 2011,[4] but the 2016 version redefined it as B0V.[3]
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.[16] Subsequent review of
Hipparcos catalog data indicated it was most likely a
Beta Cephei variable, and is hence considered a candidate for that class.[17] 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.[18] It is classified as a Beta Cephei variable by the
American Association of Variable Star Observers, and has an
apparent magnitude of +4.62.[5]
υ Orionis's
parallax has been measured at 1.14±0.25, yielding a distance of approximately 2,900
light years from
Earth.[1] 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).[16]
^
abSota, A.; Maíz Apellániz, J.; Walborn, N. R.; Alfaro, E. J.; Barbá, R. H.;
Morrell, N. I.; Gamen, R. C.; Arias, J. I. (2011). "The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-violet at R ~ 2500". The Astrophysical Journal Supplement. 193 (2): 24.
arXiv:1101.4002.
Bibcode:
2011ApJS..193...24S.
doi:
10.1088/0067-0049/193/2/24.
S2CID119248206.
^
abWatson, Christopher (17 December 2005).
"NSV 16333". AAVSO Website. American Association of Variable Star Observers. Retrieved 29 January 2014.
^Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington.
Bibcode:
1953GCRV..C......0W.
^
abMotz, Lloyd; Nathanson, Carol (1991). The Constellations: An Enthusiast's Guide to the Night Sky. London, United Kingdom:
Aurum Press. p. 116.
ISBN978-1-85410-088-7.
^Wagman, Morton (2003). Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others. Blacksburg,
VA: The McDonald & Woodward Publishing Company. p. 513.
ISBN978-0-939923-78-6.