IC 2391 (also known as the Omicron Velorum Cluster or Caldwell 85) is an

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Vela. The Persian astronomer

Al Sufi ʿAbd al-Rahman al-Sufi ( fa, عبدالرحمن صوفی; December 7, 903 – May 25, 986) was an iranianRobert Harry van Gent. Biography of al-Sūfī'. "The Persian astronomer Abū al-Husayn ‘Abd al-Rahmān ibn ‘Umar al-Sūfī was born in ...

may have first described it about 964. It was found by

Abbe Lacaille Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a French astronomer and geodesist who named 14 out of the 88 constellations. From 1750 to 1754, he studied the sky at the Cape of Goo ...

and cataloged as Lac II 5. The cluster is about 500

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

and can be seen with the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to normal ...

. It contains about 30 stars with a total

visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of 2.5, spread out along 50 arcminutes. It includes the following

naked-eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to normal ...

members: *

ο Velorum Omicron Velorum (ο Vel, ο Velorum) is a star in the constellation Vela (constellation), Vela. It is the brightest member of the loose naked eye open cluster IC 2391, also known as the ο Velorum Cluster. Omicron Velorum is a blue-whit ...

HD 74560 HY Velorum is a binary star system in the southern constellation of Vela. It is a dim star but visible to the naked eye with an apparent visual magnitude of 4.83. The distance to this system, as estimated from its annual parallax shi ...

(HY Velorum) * HD 74146 (NZ Velorum) * HD 74071 (HW Velorum) * HD 74196 * HD 74535 (KT Velorum) * HD 75466 * HD 73952 IC 2391 appears to be about the same age as the open cluster

IC 2602 IC 2602 (also known as the Southern Pleiades, Theta Carinae Cluster, or Caldwell 102) is an open cluster in the constellation Carina (constellation), Carina. Discovered by Abbe Lacaille in 1751 from South Africa, the cluster is easily visible to th ...

, and has a

lithium depletion boundary The lithium depletion boundary (LDB) technique is a method proposed for dating open clusters based on a determination of the lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number ...

age of about 50 million years. IC 2391 has been closely linked to the Argus Association of co-moving stars. Proposed members of this

moving group In astronomy, stellar kinematics is the Observational astronomy, observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar Velocity, velocities in the Milky W ...

include

Denebola Denebola is the second-brightest star in the zodiac constellation of Leo.The two components of the γ Leonis double star, which are unresolved to the naked eye, have a combined magnitude brighter than it. It has the Bayer designation ...

Epsilon Pavonis Epsilon Pavonis, Latinisation of names, Latinized from ε Pavonis, is a single, white-hued star in the constellation Pavo (constellation), Pavo. It can be viewed with the naked eye, having an apparent visual magnitude of 3.97. The annual ...

49 Ceti 49 Ceti is a single star in the equatorial constellation of Cetus. It is visible to the naked eye as a dim, white-hued star with an apparent visual magnitude of 5.607. The star is located away from the Solar System, based on its parallax ...

HD 61005 HD 61005, also known as HIP 36948, is a young star located in the southern constellation Puppis, the poop deck. It has an apparent magnitude of 8.22, making it readily visible in binoculars, but not to the naked eye. The object is loc ...

, and HD 88955. IC 2391 also includes

HD 74438 HD 74438 is a spectroscopic quadruple stellar system composed of a pair of double star systems approximately 425 light years from Earth, located in open cluster IC 2391. With an estimated age of million years, HD 74438 is the yo ...

, the youngest known quadruple star.

References

External links

* * * *

2391 In contemporary history, the third millennium of the anno Domini or Common Era in the Gregorian calendar is the current millennium spanning the years 2001 to 3000 ( 21st to 30th centuries). Ongoing futures studies seek to understand what is l ...

Open clusters Vela (constellation) 085b 64 64 {{Vela (constellation)

See also

References

External links