IC 2395 is an

open cluster An open cluster is a type of star cluster made of tens 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.

Observation history

It is possible that entry III.3 of the catalogue of

Nicolas Louis de 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 ...

, often listed as missing, is IC 2395. According to Lacaille's entry, the object consists of a "Star of 6th magnitude, connected to another more southern one by a nebulous trace", and gives the coordinates RA=08:42.2, Dec=-48:04. These coordinates are 2' west and 1' south of the location of van den Bergh-Hagen 47 according to Sky Catalogue 2000.0, which is within the cluster's diameter. Lacaille observed it on February 17, 1752. The cluster was discovered independently in 1908 by

Solon Irving Bailey Solon Irving Bailey (December 29, 1854 – June 5, 1931) was an American astronomer and discoverer of the asteroid 504 Cora, on June 30, 1902. Bailey joined the staff of Harvard College Observatory in 1887. He received a bachelor's and master' ...

Sidney van den Bergh Sidney Van den Bergh (born 20 May 1929) is a retired Dutch-Canadian astronomer. Van den Bergh showed an interest in science from an early age, learning to read with books on astronomy. In addition to being interested in astronomy, he also like ...

and Gretchen Luft Hagen catalogued also this cluster in 1975. The coordinates of vdBH 47 are in fair agreement with the coordinates of IC 2395, although because Lund placed IC 2395 in an inaccurate position, Sky Catalogue 2000.0, Deep Sky Field Guide and the first edition of Uranometria list two different clusters. The fact that they are the same cluster is also supported by Clariá et al. who estimated its angular diameter at 19 arcminutes.

Characteristics

IC 2395 is an open cluster of poor to moderate richness. 45 stars located within the central part of the cluster are considered to be possible members. The radius core radius of the cluster is 0.53 parsecs (1.6 light years), while the tidal radius is 4.5 - 7.9 parsecs (15 - 26 light years) and represents the average outer limit of IC 2395, beyond which a star is unlikely to remain gravitationally bound to the cluster core. IC 2395 is a young stellar cluster being between 6 and 18 million years old. Based on its young age and distance, it is possible that IC 2395 is part of the Vela OB1C

stellar association A stellar association is a very loose star cluster, looser than both open clusters and globular clusters. Stellar associations will normally contain from 10 to 100 or more visible stars. An association is primarily identified by commonalities in i ...

. The brightest member of the cluster has mag 5.53, and its bluest main sequence star is of spectral type B5. One of the members of the cluster is a candidate

Be star 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 ...

. One member, HD 74339 (mag. 9.3, spectral type B2/3 II/III), is a

beta Cephei variable Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200 ...

References

External links

2395 Vela (constellation) Open clusters {{Vela (constellation)