Bellatrix
| Bellatrix | |
|---|---|
| Observational Data | |
| Designation | Gamma Orionis 24 Orionis |
| Right ascension | 05h 25m 07.8633s[1] |
| Declination | +06° 20′ 58.93.18″[1] |
| Constellation | Orion |
| Magnitude | Apparent Mag: +1.64[1] Absolute Mag: -2.80[2] |
| Astrometry | |
| Distance from Earth | 252.45 ly[2] |
| Radial velocity | 18.2±0.9 km/s[1] |
| Proper motion | RA: -8.11 mas/yr[1] Dec.: -12.11 mas/yr[1] |
| Parallax | 12.92±0.52[1] |
Bellatrix (Gamma Orionis, 24 Orionis, sometimes called the Amazon star) is a giant star in the constellation of Orion, the hunter.[2] Given its Bayer designation of Gamma, it is the third brightest star in Orion and the 27th brightest star in the nigh sky.[3] The name Bellatrix means "female warrior" and may come either a latin translation of the Arabic title al-najid meaning "the conqueor" or possibly a modification of an alternate name for the contellation of Orion.[4] it is one of the four stars used in celestial navigation, .[5]
Bellatrix is a hot, luminous blue star and is also an eruptive variable star.[3] These changes in the star's output are due to violent processes such as solar flares.[6] It's magnitude only varies slightly from +1.64 to a peak of +1.59, though since it only varies due eruptive events, it averages out to +1.64.[3] The star has a spectral type of B2 III and is one of the hottest stars visible to the naked eye; it has a temperature of 18,900 kelvin.[2] The star used to be used as a standard candle but this stopped after its variable nature was discovered.
The original Hipparcos data from 1997 listed Bellatrix as lying 243.04 light years from Earth.[2] However the more recent 2007 release suggests it is slightly further away at 252.45 light years. The star is fairly large, with a mass 8-9 that of the Sun and a radius 3.18 times greater. Being larger, it emits around 6,400 times as much energy as the Sun.[3]
On July 11, 2005 the occultation of Bellatrix by Enceladus (one of Saturn's many moons) was used to investigate Enceladus' atmosphere.[7] It revealed the atmosphere is not global in scope, but is probably local to the south polar region, where most of the venting takes place.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Gamma Orionis from the SIMBAD Astronomical Database
- ↑ 2.0 2.1 2.2 2.3 2.4 Bellatrix, Gamma Orionis, 24 Orionis, HD35468, HIP25336, HR1790. Retrieved on 2018-12-28.
- ↑ 3.0 3.1 3.2 3.3 Orion Constellation. Retrieved on 2018-12-28.
- ↑ Star Names And Designations. Retrieved on 2018-12-28.
- ↑ Bellatrix – Star Facts. Retrieved on 2018-12-28.
- ↑ SuperWASP Observations of Variable Stars. Retrieved on 2018-12-28.
- ↑ "Enceladus Atmosphere Not Global." JPL, NASA, August 30, 2005. Accessed June 17, 2008.
