Upsilon Ursae Majoris

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Upsilon Ursae Majoris
Diagram showing star positions and boundaries of the Ursa Major constellation and its surroundings
Cercle rouge 100%.svg

Location of υ Ursae Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 09h 50m 59.4s
Declination +59° 02′ 19″
Apparent magnitude (V) +3.78
Distance 115 ± 3 ly
(35 ± 1 pc)
Spectral type F2 IV[1]
Other designations
υ Ursae Majoris, υ UMa, Upsilon UMa, 29 Ursae Majoris, BD+59 1268, CCDM J09510+5902A, FK5368, GC 13540, HD 84999, HIP 48319, HR 3888, IDS 09439+5931, PPM 32349, SAO 27401, WDS J09510+5902A.

Upsilon Ursae Majoris (Upsilon UMa, υ Ursae Majoris, υ UMa) is a binary star in the constellation Ursa Major. It is approximately 115 light years from Earth.

The primary component, Upsilon Ursae Majoris A, is a yellow-white F-type subgiant with a mean apparent magnitude of +3.78. It is classified as a Delta Scuti type[1] variable star and its brightness varies from magnitude +3.68 to +3.86 with a period of 3.18 hours.[dubious ] It has a projected rotational velocity of 110 km s−1, an effective temperature of 7,080 K, and a luminosity 29–30 times that of the Sun.[1]

The companion, Upsilon Ursae Majoris B, is a magnitude +11.5 star, 11.3 arcseconds away from the primary.



  1. ^ a b c Balona, L. A.; Dziembowski, W. A. (October 1999), "Excitation and visibility of high-degree modes in stars", Monthly Notices of the Royal Astronomical Society 309 (1): 221–232, Bibcode:1999MNRAS.309..221B, doi:10.1046/j.1365-8711.1999.02821.x 
  2. ^ Allen, Richard Hinckley (1899), Star-Names and Their Meanings, New York: G. E. Stechert, p. 442 
  3. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 16 日