Psi Orionis

Last updated May 03, 2019

The Bayer designation Psi Orionis (ψ Ori / ψ Orionis) is shared by two stars in the constellation Orion:

A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars.

Star An astronomical object consisting of a luminous spheroid of plasma held together by its own gravity

A star is an astronomical object consisting of a luminous spheroid of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the estimated 300 sextillion (3×10²³) stars in the Universe are invisible to the naked eye from Earth, including all stars outside our galaxy, the Milky Way.

A constellation is a group of stars that forms an imaginary outline or pattern on the celestial sphere, typically representing an animal, mythological person or creature, a god, or an inanimate object.

25 Orionis (ψ¹), a Be star
30 Orionis (ψ², often just called ψ Orionis), an ellipsoidal and eclipsing variable

Be Stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as Classical Be Stars, is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer emission lines.

Psi² Orionis a binary star system in the equatorial constellation of Orion. It has an apparent visual magnitude of 4.60, indicating that it is visible to the naked eye. Based upon an annual parallax shift of 2.87 mass, it is roughly 1,100 light years distant from the Sun.

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Orion is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous and recognizable constellations in the night sky. It was named after Orion, a hunter in Greek mythology. Its brightest stars are the supergiants: blue-white Rigel and red Betelgeuse.

Mintaka, designation Delta Orionis and 34 Orionis, is a multiple star system some 1,200 light-years from the Sun in the constellation of Orion. Together with Alnitak and Alnilam, the three stars form Orion's Belt, known by many names among ancient cultures. When Orion is near the meridian, Mintaka is the right-most of the Belt's stars when viewed from the Northern Hemisphere facing south.

In stellar evolution, an FU Orionis star is a pre–main-sequence star which displays an extreme change in magnitude and spectral type. One example is the star V1057 Cyg, which became 6 magnitudes brighter and went from spectral type dKe to F-type supergiant. These stars are named after their type-star, FU Orionis.

Alnitak, designation ζ Orionis and 50 Orionis, is a triple star system several hundred parsecs from the Sun in the constellation of Orion. It is one of the three main stars of Orion's Belt along with Alnilam and Mintaka.

Iota Orionis is a multiple star system in the equatorial constellation of Orion the hunter. It is the eighth-brightest member of Orion with an apparent visual magnitude of 2.77 and also the brightest member of the asterism known as Orion's Sword. It is a member of the NGC 1980 open cluster. From parallax measurements, it is located at a distance of roughly 2,300 light-years from the Sun.

Chi¹ Orionis is a star about 28 light years away. It is in the constellation Orion, where it can be seen in the tip of the Hunter's upraised club.

Meissa, designated Lambda Orionis is a star in the constellation of Orion. It is a multiple star approximately 1,100 ly away with a combined apparent magnitude of 3.33. The main components are an O8 giant star and a B-class main sequence star, separated by about 4".

Pi³ Orionis, also named Tabit, is a star in the equatorial constellation of Orion. At an apparent visual magnitude of 3.16, it is readily visible to the naked eye and is the brightest star in the lion's hide that Orion is holding. As measured using the parallax technique, it is 26.32 light-years distant from the Sun.

Sh2-279 is an HII region and bright nebulae that includes a reflection nebula located in the constellation Orion. It is the northernmost part of the asterism known as Orion's Sword, lying 0.6° north of the Orion Nebula. The reflection nebula embedded in Sh2-279 is popularly known as the Running Man Nebula.

Eta Orionis is a multiple star in the constellation Orion. It lies a little to the west of Orion's belt between Delta Orionis and Rigel, being closer to Delta Orionis than to Rigel. It lies at a distance of around 1,000 light years from Earth and is part of the Orion OB1 association.

Tau Orionis is a solitary star in the constellation Orion. If an imaginary line is drawn north-west between the stars Rigel and Mintaka, Tau Orionis can be found roughly one-sixth of the way to Mintaka. It is visible to the naked eye with an apparent visual magnitude of 3.58. Based upon an annual parallax shift of 6.6 mas, it is located around 490 light years from the Sun.

FU Orionis is a variable star in the constellation of Orion, that in 1937 rose in apparent visual magnitude from 16.5 to 9.6, and has since been around magnitude 9. For a long time it was considered unique, but in 1970 a similar star, V1057 Cygni, was discovered, and a number of additional examples have been discovered since then. These stars constitute the FU Orionis class of variable stars, GCVS type FU, often nicknamed FUors. These stars are pre–main sequence stars which display an extreme change in magnitude and spectral type.

V1057 Cygni (V1057 Cyg) is a FU Orionis-type variable star in the constellation of Cygnus. It has a spectral type of F and an apparent visual magnitude of approximately 11.660. It was the second FU Orionis-type variable discovered.

U Orionis is a Mira-type variable star in the constellation Orion. It is a classical long period variable star that has been well observed from the United Kingdom for over 120 years.

25 Orionis, less commonly known by its Bayer designation Psi¹ Orionis is a fifth-magnitude star in the constellation Orion. It lies among a dense cluster of low-mass pre-main-sequence stars in the Orion OB1a.

μ Orionis is a quadruple star system in the constellation Orion, similar to Mizar and Epsilon Lyrae with combined visual magnitude of 4.13. The four stars are known as Mu Orionis Aa, Mu Orionis Ab, Mu Orionis Ba, and Mu Orionis Bb. All four components are spectroscopic, with A and B systems only several tenths of an arcsec apart. The entire system is located approximately 155 Light Years from the Sun.

Omega Orionis is a star in the constellation Orion. Its apparent magnitude is 4.57 and is located approximately 1,400 light years from our solar system. It is surrounded by a cloud of dust, forming a modest reflection nebula over a light-year wide.

V883 Orionis is a protostar in the constellation of Orion. It is associated with IC 430, a peculiar Hα object surveyed by Guillermo Haro in 1952. It is located about 1350 light years away, and is associated with the Orion Nebula.

GW Orionis is a T Tauri type pre-main sequence hierarchical triple star system. It is associated with the Lambda Orionis star-forming region and has an extended circumtrinary protoplanetary disk.