Bellatrix
Star Bellatrix (γ Orionis) |
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Bellatrix is the bright blue star in the lower right. The red star at the bottom left is Betelgeuse and the slightly less bright blue star in the middle of the large emission nebula is Meissa (λ Orionis). | |||||||||||||||||||
AladinLite | |||||||||||||||||||
Observation dates equinox : J2000.0 , epoch : J2000.0 |
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Constellation | Orion | ||||||||||||||||||
Right ascension | 05 h 25 m 7.86 s | ||||||||||||||||||
declination | + 06 ° 20 ′ 58.9 ″ | ||||||||||||||||||
Apparent brightness | 1.64 likes | ||||||||||||||||||
Typing | |||||||||||||||||||
B − V color index | −0.22 | ||||||||||||||||||
U − B color index | −0.87 | ||||||||||||||||||
R − I index | −0.22 | ||||||||||||||||||
Spectral class | B2 III | ||||||||||||||||||
Astrometry | |||||||||||||||||||
Radial velocity | (18.2 ± 0.9) km / s | ||||||||||||||||||
parallax | (12.92 ± 0.52) mas | ||||||||||||||||||
distance | (252 ± 10) ly (77.4 ± 3.1) pc |
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Visual absolute brightness M vis | −2.80 mag | ||||||||||||||||||
Proper movement | |||||||||||||||||||
Rec. Share: | (−8.11 ± 0.50) mas / a | ||||||||||||||||||
Dec. portion: | (−12.88 ± 0.35) mas / a | ||||||||||||||||||
Physical Properties | |||||||||||||||||||
radius | (5.4 ± 0.8) R ☉ | ||||||||||||||||||
Luminosity |
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Other names and catalog entries |
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Bellatrix (lat. "Warrior") or γ Orionis is the third brightest star in the constellation Orion . Along with Betelgeuse, she is Orion's other (right) shoulder star.
properties
Bellatrix, about 250 light years away, has an apparent magnitude of 1.64, making it one of the 50 brightest stars in the night sky. As a bluish giant star of the spectral class B2 it has about eight times the mass of the sun and about 4000 times the bolometric luminosity .
In a few million years at the most, it will expand into a red giant , but due to its slightly insufficient mass, it will not explode, but will end up as a massive white dwarf .
Bellatrix does not belong - as long assumed - to the Orion association , but is much less far from the sun.
In 1972 it was found to have slight fluctuations in brightness in the range of a few hundredths of a size class .
Trivia
The star is namesake for SS Bellatrix (T-AKR-288), a fast Algol-class cargo ship in the United States Navy .
See also
Web links
Individual evidence
- ↑ a b c d Hipparcos catalog (ESA 1997)
- ↑ a b c Bright Star Catalog
- ↑ Pulkovo radial velocities for 35493 HIP stars
- ↑ a b c Hipparcos, the New Reduction (van Leeuwen, 2007)
- ↑ JMMC Stellar Diameters Catalog - JSDC (Lafrasse +, 2010) (calculated from the data values LDD and Plx)