Bellatrix (Gamma Orionis)
Bellatrix (Gamma Orionis) is a star in the constellation Orion, magnitude 1.6.
The Female Warrior at Orion’s shoulder — a hot blue star with a borrowed name.
Bellatrix is a hot blue star about 8.4 times the Sun’s mass and six times its width, with a surface at around 22,000 K — nearly four times hotter than the Sun’s. Heavy stars live fast. At about 28 million years old, it should run out of core hydrogen within another seven million years, then swell and cool. It may end in a supernova.
Its name is Latin for ‘female warrior’, and it was borrowed. The medieval writers Abu Ma’shar and Johannes Hispalensis used it for Capella; astronomers in 15th-century Vienna moved it to Orion. It was also called the Amazon Star.
It is no sibling of the Belt stars, either. Once thought to belong to their family, the Orion OB1 association, it turned out to be much closer to us than the rest — the nearest of Orion’s major stars.
Bellatrix (Gamma Orionis) is 250 light-years away: the light we see from it set off around 1775, around the time William Herschel discovered Uranus.
Did you know?
- Those placed far apart. To the Inuit, Betelgeuse and Bellatrix high in the southern sky after sunset marked the coming of spring and longer days. They called the pair Akuttujuuk, ‘those placed far apart’.
- An unreliable standard. In 1963 Bellatrix was one of the bright stars chosen to define the UBV brightness system, its magnitude fixed at 1.64. A 1988 survey then found that it varies slightly — awkward for a standard star.
- The sparkling pigment. The Wardaman people of northern Australia know Bellatrix as Banjan, the sparkling pigment used in ceremonies led by Rigel, the Red Kangaroo Leader.
The blue-white star at Orion’s western shoulder, opposite red Betelgeuse at the other. Look from one to the other to compare a hot blue star with a cool red one.
When and where to see it
It is best placed in the evening sky around January, when it crosses the meridian at about 10 pm local time (around midnight in December). It can be seen from everywhere north of 84°S and never sets north of 84°N.
At its highest it stands 46° up from 50°N, 61° up from 35°N, 84° up from the equator, 49° up from 35°S.
Facts
- Type
- Star
- Constellation
- Orion
- Designations
- Gamma Orionis, γ Ori, 24 Ori, HR 1790, HD 35468, HIP 25336
- Magnitude
- 1.6
- Position
- RA 5h 25.1m, Dec +6° 21′ (J2000)
- Spectral type
- B2III
- Colour
- blue-white (B−V -0.22)
- Distance
- 250 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Bellatrix (Gamma Orionis) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.