Gamma Leonis

γ Leonis
Location of γ Leonis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Leo
Right ascension 10h 19m 58.35056s[1]
Declination +19° 50′ 29.3468″[1]
Apparent magnitude (V) 2.08 (2.37/3.64)[2]
Characteristics
Evolutionary stage Red clump (both stars)[3]
Spectral type K0III + G7III[3]
U−B color index 1.00
B−V color index 1.14
Variable type RS CVn[4]
Astrometry
Radial velocity (Rv)−36.24±0.18[5] km/s
Proper motion (μ) RA: +304.30[1] mas/yr
Dec.: −154.28[1] mas/yr
Parallax (π)25.07 ± 0.52 mas[1]
Distance130 ± 3 ly
(39.9 ± 0.8 pc)[1]
Absolute magnitude (MV)−0.27/+0.98[6]
Orbit[3][note 1]
Period (P)554±27 yr
Semi-major axis (a)3.1±0.1
Eccentricity (e)0.93±0.02
Inclination (i)41±5°
Longitude of the node (Ω)143.4[7]°
Periastron epoch (T)1671.3[7]
Details[3]
γ Leo A
Mass1.66±0.14 M
Radius26.08±0.79 R
Luminosity250 L
Surface gravity (log g)1.8±0.04 cgs
Temperature4457±63 K
Metallicity [Fe/H]−0.41±0.03 dex
Rotational velocity (v sin i)1.41 km/s
Age1.75±0.43 Gyr
γ Leo B
Mass1.55±0.08 M
Radius10.55±0.29 R
Luminosity63.1 L
Surface gravity (log g)2.56±0.04 cgs
Temperature4969±15 K
Metallicity [Fe/H]–0.38 ± 0.02 dex
Rotational velocity (v sin i)1.62 km/s
Age2.12±0.33 Gyr
Other designations
Algieba, γ Leonis, 41 Leo, NSV 4823, BD+20°2467, HIP 50583, WDS 10200+1950, LTT 12764/12765
γ Leo A: γ1 Leonis, HD 89484, HR 4057, SAO 81298
γ Leo B: γ2 Leonis, HD 89485, HR 4058, SAO 81299
Position (relative to A)[2]
ComponentB
Epoch of observation1820 – 2022
Angular distance3.7" (1820), 4.7" (2022)
Database references
SIMBADdata
Exoplanet Archivedata

Gamma Leonis (γ Leonis, abbreviated Gamma Leo, γ Leo), also named Algieba /ælˈbə/,[8][9] is a binary star system in the constellation of Leo, made up of two red giants. In 2009, a planetary companion around the primary was announced.

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