Upsilon Leonis

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υ Leonis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Leo
Right ascension 11h 36m 56.92983s[1]
Declination +00° 49′ 25.8758″[1]
Apparent magnitude (V) 4.33[2]
Spectral type G9 III[3]
U−B color index +0.76[2]
B−V color index +1.00[2]
Radial velocity (Rv) 1.79±0.16[4] km/s
Proper motion (μ) RA: +1.76[1] mas/yr
Dec.: +43.37[1] mas/yr
Parallax (π) 17.97 ± 0.22[1] mas
Distance 182 ± 2 ly
(55.6 ± 0.7 pc)
Absolute magnitude (MV) 0.59[5]
Mass 2.58[5] M
Radius 11[4] R
Luminosity 56[4] L
Surface gravity (log g) 2.7[4] cgs
Temperature 4,842[4] K
Metallicity [Fe/H] –0.34[4] dex
Rotational velocity (v sin i) 0.0[4] km/s
Age 4.12±2.08[6] Gyr
Other designations
υ Leo, 91 Leo, BD−00° 2458, FK5 437, HD 100920, HIP 56647, HR 4471, SAO 138298.[7]
Database references

Upsilon Leonis (υ Leo) is a star in the zodiac constellation of Leo. It is visible to the naked eye with an apparent visual magnitude of 4.33.[2] The distance to this star, as determined using parallax measurements,[1] is about 182 light years. At that distance, the visual magnitude of the star is diminished by an estimated extinction factor of 0m.02 because of interstellar dust.[5]

With an age of around 4 billion years, this star has evolved into a G-type giant star with a stellar classification of G9 III.[3] It has 2.6 times the Sun's mass,[5] but has expanded to 11 times the solar radius and shines with 56 times the luminosity of the Sun at an effective temperature of 4,842 K.[4] The rate of rotation is too small to be measured, with a projected rotational velocity of 0.0 km/s.[4] The chemical abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is less than half that in the Sun.[4] It is most likely a member of the galactic thin disk population.[6]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4, Bibcode:1962MtSOM...4....1B. 
  4. ^ a b c d e f g h i j Massarotti, Alessandro; et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209. 
  5. ^ a b c d Takeda, Yoichi; et al. (February 2005), "Stellar Parameters and Photospheric Abundances of Late-G Giants: Properties of the Targets of the Okayama Planet Search Program", Publications of the Astronomical Society of Japan, 57 (1): 109–125, Bibcode:2005PASJ...57..109T, doi:10.1093/pasj/57.1.109. 
  6. ^ a b Soubiran, C.; et al. (March 2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics, 480 (1): 91–101, arXiv:0712.1370Freely accessible, Bibcode:2008A&A...480...91S, doi:10.1051/0004-6361:20078788. 
  7. ^ "ups Leo -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-09-29.