Gamma Orionis
Encyclopedia
Bellatrix, also known by its Bayer designation
Gamma Orionis (γ Ori, γ Orionis), is the third brightest star
in the constellation
Orion
, the twenty-seventh brightest star in the night sky, and one of the brightest second-magnitude stars.
The name Bellatrix is Latin
for female warrior. It is also known as the Amazon Star
. It was once thought to belong to the Orion OB1 Association
along with the "Orion's Belt" stars ζ Ori (Alnitak), ε Ori
(Alnilam), and δ Ori
(Mintaka), but this is no longer believed to be the case, as Gamma Orionis is now known to be much closer than the rest of the group, lying 245 light years away.
Historically this star was used as a luminosity standard to compare with other stars to check for variability, but it was later discovered that Bellatrix itself is an eruptive variable, changing in luminosity by a few percent over time. It ranges in apparent magnitude from 1.59 to 1.64. It has an absolute magnitude of -2.72.
Bellatrix is one of the navigational stars
used in celestial navigation
.
The Chinese
name for the star is 参宿五 ("The Fifth of the Three Stars").
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...
Gamma Orionis (γ Ori, γ Orionis), is the third brightest star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Orion
Orion (constellation)
Orion, often referred to as The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous, and most recognizable constellations in the night sky...
, the twenty-seventh brightest star in the night sky, and one of the brightest second-magnitude stars.
The name Bellatrix is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for female warrior. It is also known as the Amazon Star
Amazons
The Amazons are a nation of all-female warriors in Greek mythology and Classical antiquity. Herodotus placed them in a region bordering Scythia in Sarmatia...
. It was once thought to belong to the Orion OB1 Association
Orion OB1 Association
The Orion OB1 stellar association is a contingent group of several dozen hot giant stars of spectral types O and B. Associated are thousands of lower-mass stars, and a number of protostars. It is part of the larger Orion Molecular Cloud Complex...
along with the "Orion's Belt" stars ζ Ori (Alnitak), ε Ori
Epsilon Orionis
Alnilam is a large blue supergiant star in the constellation of Orion. Its Flamsteed designation is 46 Orionis....
(Alnilam), and δ Ori
Delta Orionis
Delta Orionis , traditionally known as Mintaka , is a star some 900 light years distant in the constellation Orion. Together with Zeta Orionis and Epsilon Orionis , the three stars make up the belt of Orion, known by many names across many ancient cultures...
(Mintaka), but this is no longer believed to be the case, as Gamma Orionis is now known to be much closer than the rest of the group, lying 245 light years away.
Historically this star was used as a luminosity standard to compare with other stars to check for variability, but it was later discovered that Bellatrix itself is an eruptive variable, changing in luminosity by a few percent over time. It ranges in apparent magnitude from 1.59 to 1.64. It has an absolute magnitude of -2.72.
Bellatrix is one of the navigational stars
Navigational stars
Fifty-eight selected navigational stars are given a special status in the field of celestial navigation. Of the approximately 6,000 stars visible to the naked eye under optimal conditions, the selected stars are among the brightest and span thirty-eight constellations of the celestial sphere from...
used in celestial navigation
Celestial navigation
Celestial navigation, also known as astronavigation, is a position fixing technique that has evolved over several thousand years to help sailors cross oceans without having to rely on estimated calculations, or dead reckoning, to know their position...
.
The Chinese
Chinese language
The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...
name for the star is 参宿五 ("The Fifth of the Three Stars").