γ Orionis
Bellatrix
The Amazon Star · Blue giant
At a glance
- Distance
- 252.4 ly
- Constellation
- Orion
- Type
- B2III
- Apparent magnitude
- 1.64
- Absolute magnitude
- -2.78
- Mass
- 8.6 M☉
- Radius
- 6.4 R☉
- Luminosity
- 7,410 L☉
- Surface temp
- 22,017 K
- Age
- 0.025 billion yrs
The story
Bellatrix — Latin for 'female warrior' — marks the left shoulder of Orion the Hunter. Its name was used in medieval astrology to denote a star of martial fortune, and the IAU formally adopted it in 2016. At magnitude 1.64 it ranks as the 25th-brightest star in the night sky, blazing a hot blue-white.
With a mass of 8.6 times the Sun and a surface temperature of 22,000 K, Bellatrix is one of the hottest stars visible to the naked eye. It is classified as a B2 giant, meaning it has already expanded slightly from the main sequence and is burning through its hydrogen at a ferocious rate. Its luminosity of roughly 7,400 Suns puts most of that energy into ultraviolet light invisible to our eyes.
At only 25 million years old, Bellatrix is an astronomical infant, yet it is already near the twilight of its short life. It belongs to the Orion OB1 stellar association, the same nursery of massive young stars that includes Rigel and the Orion Nebula, offering a snapshot of recent star formation at 252 light-years from Earth.
Compared to the Sun
Sun
This star · 6.4× radius
It shines about 7,410 times as bright as the Sun.
Its fate
With hydrogen likely exhausted within around seven million years, Bellatrix will expand into a red or orange supergiant and eventually expel its outer layers, leaving a stellar-mass black hole — too massive to settle as a neutron star or white dwarf.
Find it in the sky
Orion is unmissable on winter evenings in the northern hemisphere. Bellatrix is the bright blue-white star forming Orion's right shoulder (to your upper left as you face south). It sits about 5° west of the ruddy supergiant Betelgeuse.
