|Observation data (J2000.0 epoch)|
|Right ascension||08h 40.6m|
|Apparent magnitude (V)||2.5|
|Apparent dimensions (V)||50′|
|Other designations||C 0838-528, Caldwell 85|
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.
The cluster is about 500 light-years away from Earth and can be seen with the naked eye. It contains about 30 stars with a total visual magnitude of 2.5, spread out along 50 arcminutes. The cluster 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.
- Stauffer, J.R.; et al. (1997). "Rotational Velocities and Chromospheric/Coronal Activity of Low-Mass Stars in the Young Open Clusters IC 2391 and IC 2602". Astrophysical Journal. 479 (2): 776. Bibcode:1997ApJ...479..776S. doi:10.1086/303930.
- Barrado y Navascues, D., Stauffer, J.R., & Jayawardhana, R. (2002). "Spectroscopy of Very Low Mass Stars and Brown Dwarfs in IC 2391: Lithium Depletion and Hα Emission". Astrophysical Journal. 614 (1): 386–397. arXiv:. Bibcode:2004ApJ...614..386B. doi:10.1086/423485.
- IC 2391 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
- SEDS: entry for IC 2391
- Atlas of the Universe: list of open clusters
- Simbad: entry for IC 2391