- Bellatrix
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For other uses, see Bellatrix (disambiguation).
Bellatrix (γ Orionis) 
Bellatrix is located to the upper right of center.Observation data
Epoch J2000 Equinox J2000Constellation Orion Pronunciation /ˈbɛlətrɪks/ Right ascension 05h 25m 07.9s Declination +06° 20' 59" Apparent magnitude (V) 1.64 Characteristics Spectral type B2 III U−B color index -0.87 B−V color index -0.22 Variable type Eruptive Astrometry Radial velocity (Rv) +18.2 km/s Proper motion (μ) RA: -8.75 mas/yr
Dec.: -13.28 mas/yrParallax (π) 13.42 ± 0.98 mas Distance 240 ± 20 ly
(75 ± 5 pc)Absolute magnitude (MV) -2.72 Details Mass 8-9 M☉ Radius 5.7 R☉ Luminosity 4,000 L☉ Temperature 21,500 K Metallicity ? Rotation ? Age ? years Other designations Bellatrix, also known by its Bayer designation Gamma Orionis (γ Ori, γ Orionis), is the third brightest star in the constellation Orion, the twenty-seventh brightest star in the night sky, and one of the brightest second-magnitude stars.
The name Bellatrix is Latin for female warrior. It is also known as the Amazon Star. It was once thought to belong to the Orion OB1 Association along with the "Orion's Belt" stars ζ Ori (Alnitak), ε Ori (Alnilam), and δ Ori (Mintaka), but this is no longer believed to be the case, as Gamma Orionis is now known to be much closer than the rest of the group, lying 245 light years away.
Historically this star was used as a luminosity standard to compare with other stars to check for variability, but it was later discovered that Bellatrix itself is an eruptive variable, changing in luminosity by a few percent over time. It ranges in apparent magnitude from 1.59 to 1.64. It has an absolute magnitude of -2.72.
Bellatrix is one of the navigational stars used in celestial navigation.
The Chinese name for the star is 参宿五 ("The Fifth of the Three Stars").
References
Stars of Orion Bayer α (Betelgeuse) • β (Rigel) • γ (Bellatrix) • δ (Mintaka) • ε (Alnilam) • ζ (Alnitak) • η (Algjebba) • θ¹ (Trapezium Cluster: θ¹ A • θ¹ B • θ¹ C • θ¹ D) • θ² • ι (Hatsya) • κ (Saiph) • λ (Meissa) • μ • ν • ξ • ο¹ • ο² • π¹ • π² • π³ (Tabit) • π4 • ρ • σ • τ • υ (Thabit) • φ¹ • φ² • χ¹ • χ² • ψ • ω • b • c • d • e • f¹ • f² • g • h • i • k • l • m • n¹ • n² • o • p • AFlamsteed 1 (π³, Tabit) • 2 (π²) • 3 (π4) • 4 (ο¹) • 5 • 6 (g) • 7 (π¹) • 9 (ο²) • 11 • 12 • 13 • 14 (i) • 15 • 16 (h) • 17 (ρ) • 18 • 19 (β, Rigel) • 20 (τ) • 21 • 22 (o) • 23 (m) • γ (Bellatrix) • 25 • 26 • 27 (p) • 28 (η, Algjebba) • 29 (e) • 30 (ψ) • 31 • 32 (A) • 33 (n¹) • 34 (δ, Mintaka) • 35 • 36 (υ, Thabit) • 37 (φ¹) • 38 (n²) • 39 (λ, Meissa) • 40 (φ²) • 41 (θ¹, Trapezium Cluster: θ¹ A • θ¹ B • θ¹ C • θ¹ D) • 42 (c) • 43 (θ²) • 44 (ι, Hatsya) • 45 • 46 (ε, Alnilam) • 47 (ω) • 48 (σ) • 49 (d) • 50 (ζ, Alnitak) • 51 (b) • 52 • 53 (κ, Saiph) • 54 (χ¹) • 55 • 56 • 57 • 58 (α, Betelgeuse) • 59 • 60 • 61 (μ) • 62 (χ²) • 63 • 64 • 65 • 66 • 67 (ν) • 68 • 69 (f¹) • 70 (ξ) • 71 • 72 (f²) • 73 • 74 (k) • 75 (l)Nearby GJ 3379 • Gliese 205 • Ross 47 • Gliese 223.2 • GJ 1087 • π³ (Tabit) • χ¹Other S • HD 36960Categories:- Giant star stubs
- Bayer objects
- B-type giants
- Orion constellation
- Eruptive variables
- Stars with proper names
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