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

Vela Vela or Velas may refer to: Astronomy * Vela (constellation), a constellation in the southern sky (the Sails) ** Vela (Chinese astronomy) ** Vela Pulsar ** Vela X-1, a pulsing, eclipsing high-mass X-ray binary system Places * Vela Bluff, Antarc ...

. The Persian astronomer Al Sufi may have first described it about 964. It was found by Abbe Lacaille 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 101 ...

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 surf ...

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 lig ...

of 2.5, spread out along 50 arcminutes. It includes the following naked-eye members: * ο Velorum * HD 74560 (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, and has a lithium depletion boundary age of about 50 million years. IC 2391 has been closely linked to the

Argus Association IC 2391 (also known as the Omicron Velorum Cluster or Caldwell 85) is an open cluster in the constellation Vela. The Persian astronomer Al Sufi may have first described it about 964. It was found by Abbe Lacaille and cataloged as Lac II 5. Th ...

of co-moving stars. Proposed members of this moving group include Denebola, Epsilon Pavonis,

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, and HD 88955. IC 2391 also includes HD 74438, 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