Bellatrix's Vital Stats:

Official nameBellatrix
Other designationsGamma Orionis, HIP 25336, HD 35468, HR 1790
NicknamesAmazon Star
Apparent magnitude1.64
Distance from Earth252 light-years
Mass8 solar masses
Radius6 solar radii
Right ascension05h 25m 07s
Declination+06° 20' 58”
Multiple system?No
Variable star?Yes
Exoplanets statusNone known
Probable fateUncertain

Physical Characteristics

Bellatrix shines on a moonlit night, with clouds nearby.
Daniel Johnson

The Orion constellation is something of a gold mine, and we’ve dug into a few of these treasures in the past, including Rigel, Betelgeuse, and Alnilam. Now, we turn our attention to another shiny gem: the brilliant blue star Bellatrix on Orion’s other shoulder

If you’re unfamiliar with this star, don’t feel bad. If Bellatrix were located in just about any other constellation, it would probably be the “star of the show,” but as it stands, Bellatrix takes a backseat to brighter Rigel and Betelgeuse. It’s further overlooked because of the three-star belt and the Orion Nebula and Horsehead nebulae. However, at 2nd magnitude, Bellatrix is truly a brilliant star.

At first glance Bellatrix appears white, but a little time watching will reveal its blue color, especially in contrast to nearby red Betelgeuse. And when it comes to stars, blue means hot. The star’s surface is heated to a roaring 21,750 kelvin (40,000°F) — a difficult quantity to comprehend even though there are plenty of stars even hotter. By comparison, the Sun’s surface is about 5800K, giving it a white/yellow color. If Earth were orbiting Bellatrix, lighting conditions would be unusually blue.

Bellatrix’s spectral type of B2V is also interesting. While the star has some spectral signatures of a giant, it’s not giant yet — it’s simply a main sequence star that’s hotter and larger than the Sun, similar to Sirius. Bellatrix still has millions of years left before it enters the giant phase.

Bellatrix is something of a minor variable star, meaning that its brightness rises and falls slightly over time. But the fluctuation is both small and seemingly random, so observing the effect with amateur equipment is tricky if not downright impossible.

Eventually, Bellatrix should expand into a giant star, but its ultimate fate is unknown. Bellatrix has a mass of somewhere around 8 to 9 solar masses, but that number represents the knife-edge of a star’s future. Stars with a mass higher than this eventually form a brilliant supernova, while smaller ones quietly settle down into stellar retirement as a white dwarf. We’re not sure which path Bellatrix will take because other factors — such as how much mass it will lose toward the end of its life — are hard to predict.

Origin / Mythology

Orion behind thin clouds
Orion shines through thin clouds; Bellatrix, Betelgeuse, and Rigel are labeled.
Daniel Johnson

Students of astronomy know well that Orion is the great hunter of classical Greek myth. Bellatrix marks one of Orion’s shoulders, although whether it’s his left shoulder or right depends on if you imagine him facing towards or facing away (artistic representations have shown him in both positions over the centuries). Outside the Mediterranean, there is no shortage of cultures who claimed the stick figure in the sky as a great hunter, warrior, giant, and some other larger-than-life hero in their cultural lore. So it’s a curious journey to dig into the etymology of the name Bellatrix, Latin for “female warrior.”

A word meaning warrior is certainly a good fit for a star in a constellation globally associated with heroic deeds; indeed, the star’s Arabic name means conqueror. What’s not clear is why the feminine Latin form is used over the masculine form, which would be Bellator. The answer might be that the name Bellatrix has its origins in another part of the sky entirely, separate from Orion.

The name Bellatrix was already floating around in the 800s AD, attached to the star we now know as Capella (or alpha Aurigae). Around the late 15th century, star catalogers seized on the idea of transferring the name to Orion (perhaps because a warrior’s name would be more suitable for a star belonging to the Hunter.). So the name was relocated from alpha Aurigae to gamma Orionis. Orion’s shoulder was thereafter the woman warrior. Because of this, Bellatrix is sometimes called the Amazon Star, in reference to the mythical Greek characters.

Interestingly, a different Amazon — this time, the South American river — also has a connection to the star we call Bellatrix. Rainforest societies there depicted the star as a canoe piloted by a boy, with nearby Betelgeuse taking the part of an elderly man. 

How to See Bellatrix

Orion stars with barn in foreground
Orion gleams in the winter sky. Sirius is also labeled.
Daniel Johnson

Orion is spectacular to behold and easy to find in the winter. While the precise direction you look depends on the month and the time of night, it’s always going to be in a roughly southern direction when viewed from the Northern Hemisphere. Orion isn’t a zodiac constellation like its neighbors Gemini and Taurus, but instead slides along the sky just beneath the ecliptic. Because of this, the Moon visits Orion once a month, just above his head. Orion is easy to spot for its belt of three bright stars in a line.

As for Bellatrix itself, the bright star marks the upper right shoulder of Orion when looking up from the ground. Don’t confuse it with Orion’s head, which is made up of a trio of much fainter 3rd- and 4th-magnitude stars. Bellatrix is often accompanied by a fierce twinkling similar to bright Sirius or Capella, especially when the constellation is low on the sky early on December or January evenings. Try it tonight — it’s a star you should have no trouble finding.

Daniel Johnson is a Wisconsin-based freelance writer and professional photographer and the co-author of over a dozen books. He’s a longtime amateur astronomer and fortunate enough to live in a rural region with excellent seeing conditions. You can view some of Dan’s photography (he does a lot of animals!) at


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Andrew James

January 24, 2024 at 6:24 pm

It seems that the broader reason why B-type stars are so different is due to the problem that they are a closely knitted group on the H-R diagram with a large range in temperature. Lower spectral classes are likely more easily differentiated based on luminosity and colour. Not so for B-stars. According to Garrison & Gray (1994), “The MK classification system for the B type stars has undergone some revision and refinement by Morgan. This refined classification system is encapsulated in the system of MK dagger standards (Morgan & Keenan 1973) and further elaborated in the spectral atlas of Morgan et al. (1978).”
Bellatrix classification was once B2III and now considered B2V as is determined by its spectrum. Why? Luminosity classes show small differences indicated by unexpected deviations with narrow β (δβ) when using Strömgren photometry. Why this is happening is still to be fully determined, but the basis of the change from III to V luminosity class is the Strömgren photometry observations made in 1968.
After about 1990, all the B-types have their luminosity classes depend on Si/He line ratios, Stark effects in certain He I lines, and to a lesser extent, the CNO line structures. Determined ratios are mainly between the two selected lines Si III at 455.2nm & He II at 438.7nm, with ratio differences gradually decreasing between luminosity B Ia to B V. This ratio is more pronounced with stars having rich OII spectra in B Ia/Ia+ and are distinguished by the [Fe II] emission line at 447.1 nm. that exists on either side of the Hγ line at 434.047 nm. High ratios between He lines at 414.4 nm. & 412.1 nm. define the spectral classes of B2 (or B3) stars. B-type stars have their luminosity classes based on their spectra, which is different for other types of stars based on their physical size. Importantly, once the luminosity class is selected, then Teff, mass, luminosity, age, etc. can be determined.
I would point out, that your statement "Bellatrix still has millions of years left before it enters the giant phase." is true, but by then it will not be a B2I star, but a cooler giant and different in spectral class.
Standard luminosity classes for B2 stars were once as follows, HD 141318 B2 II, Gamma Orionis B2III, Gamma Pegasi B2 IV & HD 42401 for B2 V.
Note using the new system reduces Bellatrix to B2V, changing the sequence. However there are complications with this stuff because it maybe a spectroscopic binary, it is shown to be slightly variable in brightness.

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January 26, 2024 at 11:15 pm

Can you say why Bellatrix will evolve into a cooler giant and not a blue giant or super-giant?

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Andrew James

January 27, 2024 at 12:46 am

Simply. B2V stars have high mass, typically ranging from 4 to 16 Solar masses. Due to their higher mass, they have shorter lifetimes compared to lower mass stars. After several million to tens of millions of years, the hydrogen in their cores starts depleting. The star expands to red giant, because the hydrogen fuel runs out in the core, it begins to contract and heat up, causing the outer layers of the star to expand. Hence, all B2V star will evolve into or towards a red giant. During this phase, the star swells up in size, becoming much larger and cooler than before. Temperature decreases as the volume increases, caused by the energies of gravitation collapsing the core that forces the outer regions of the star to expand.

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Andrew James

January 24, 2024 at 6:29 pm

Also a bit of trivia. Bellatrix Lestrange is a character in the Harry Potter books.

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January 27, 2024 at 5:44 pm

In "Planet of the Apes" (1968) the astronauts thought that they might have landed in the Bellatrix system.

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