IC 2395 | |
---|---|
Observation data (J2000 epoch) | |
Right ascension | 08h 42m 31s [1] |
Declination | −48° 06′ 00″ [1] |
Distance | 2,300 ly (705 pc [2] ) |
Apparent magnitude (V) | 4.6 [1] |
Apparent dimensions (V) | 8' |
Physical characteristics | |
Mass | 176 [3] M☉ |
Estimated age | 17 million years [2] |
Other designations | Cr 192, vdBH 47 |
Associations | |
Constellation | Vela |
IC 2395 is an open cluster in the constellation Vela.
It is possible that entry III.3 of the catalogue of Nicolas Louis de Lacaille, 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. [4] 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. [5] Lacaille observed it on February 17, 1752. [6]
The cluster was discovered independently in 1908 by Solon Irving Bailey. Sidney van den Bergh 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. [6] The fact that they are the same cluster is also supported by Clariá et al. who estimated its angular diameter at 19 arcminutes. [7]
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 [3] 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. [8] IC 2395 is a young stellar cluster being between 6 [7] and 18 [8] million years old. Based on its young age and distance, it is possible that IC 2395 is part of the Vela OB1C stellar association. [7]
The brightest member of the cluster has mag 5.53, and its bluest main sequence star is of spectral type B5. [6] One of the members of the cluster is a candidate Be star. [9] One member, HD 74339 (mag. 9.3, spectral type B2/3 II/III), is a beta Cephei variable. [10]
The Butterfly Cluster is an open cluster of stars in the southern constellation of Scorpius. Its name derives from the resemblance of its shape to a butterfly.
Messier 18 or M18, also designated NGC 6613 and sometimes known as the Black Swan Cluster, is an open cluster of stars in the constellation Sagittarius. It was discovered by Charles Messier in 1764 and included in his list of comet-like objects. From the perspective of Earth, M18 is situated between the Omega Nebula (M17) and the Small Sagittarius Star Cloud (M24).
Messier 36 or M36, also known as NGC 1960 or the Pinwheel Cluster, is an open cluster of stars in the somewhat northern Auriga constellation. It was discovered by Giovanni Batista Hodierna before 1654, who described it as a nebulous patch. The cluster was independently re-discovered by Guillaume Le Gentil in 1749, then Charles Messier observed it in 1764 and added it to his catalogue. It is about 1,330 pc away from Earth. The cluster is very similar to the Pleiades cluster (M45), and if as far away it would be of similar apparent magnitude.
Messier 69 or M69, also known NGC 6637, and NGC 6634, is a globular cluster in the southern constellation of Sagittarius. It can be found 2.5° to the northeast of the star Epsilon Sagittarii and is dimly visible in 50 mm aperture binoculars. The cluster was discovered by Charles Messier on August 31, 1780, the same night he discovered M70. At the time, he was searching for an object described by Nicolas-Louis de Lacaille in 1751–2 and thought he had rediscovered it, but it is unclear if Lacaille actually described M69.
Messier 75 or M75, also known as NGC 6864, is a giant globular cluster of stars in the southern constellation Sagittarius. It was discovered by Pierre Méchain in 1780 and included in Charles Messier's catalog of comet-like objects that same year.
Messier 93 or M93, also known as NGC 2447 or the Critter Cluster, is an open cluster in the modestly southern constellation Puppis, the imagined poop deck of the legendary Argo.
NGC 2546 is a pair of independent but overlapping open clusters located in the southern constellation of Puppis. This grouping was discovered by French astronomer Abbe Lacaille in 1751-1752 from South Africa. NGC 2546 is just visible to the naked eye as a fuzzy patch; the brightest component has an apparent visual magnitude of 6.44. The brighter members are readily resolved with a pair of 10×50 binoculars.
IC 2391 is an open cluster in the constellation Vela consisting of hot, young, blueish stars, some of which binaries and one of which is a quadruple. Persian astronomer A. a.-R. al-Sufi first described it as "a nebulous star" in c. 964. It was re-found by Abbe Lacaille and cataloged as Lac II 5.
NGC 6281 is an open cluster of stars in the constellation Scorpius. It was not included in the Messier or Caldwell catalogues of nebulous objects, but it is the brightest such cluster in the constellation to be left out of both. It is readily observed with the naked eye; it is located about 2° to the east of Mu Scorpii. James Dunlop described the cluster as a "curiously curved line of pretty bright stars, with many stars mixt". John Herschel then described the cluster as both "pretty bright" and "pretty rich".
NGC 2439 is a sparse open cluster of stars in the constellation Puppis. It has an apparent visual magnitude of 6.9, an angular size of 10 arcminutes, and is visible using a small telescope. This is a young cluster with age estimates in the range of 20–300 million years. It has a tidal radius of approximately 82 light years. No chemically peculiar stars have been found.
NGC 2539 is an open cluster in the constellation Puppis, located at the north edge of the constellation. It was discovered by William Herschel on January 31, 1785. It is a moderately rich cluster and with little central concentration, with Trumpler class II1m.
NGC 5662 is an open cluster in the constellation Centaurus. It was discovered by Nicolas Louis de Lacaille on May 17, 1752 from South Africa. James Dunlop observed it on July 10, 1826 from Parramatta, Australia and added it to his catalog as No. 342.
NGC 3228 is an open cluster in Vela. It was discovered by Nicolas Louis de Lacaille in 1751–1752, while he was in South Africa and catalogued it as Lac II.7. It is small but bright and can be observed easily with binoculars in sufficiently dark skies.
NGC 5281 is an open cluster in the constellation Centaurus. It was discovered by Nicolas Louis de Lacaille in 1751-1752 from South Africa, and catalogued it as Lacaille I.7. NGC 5281 is located three and a quarter degrees southwest of Beta Centauri. Under dark skies, it is bright enough to be spotted with naked eye, appearing as a 6th magnitude star.
NGC 4349 is an open cluster in the constellation Crux. It was discovered by James Dunlop in 1826. It is located approximately 7,000 light years away from Earth.
IC 2488 is an open cluster in the constellation Vela. It was discovered by Nicolas-Louis de Lacaille in 1752. It is located approximately 3,700 light years away from Earth.
IC 2714 is an open cluster in the constellation Carina. It was discovered by James Dunlop in 1826. It is located approximately 4,000 light years away from Earth, in the Carina–Sagittarius Arm.
NGC 2527 is an open cluster in the constellation Puppis. It was discovered by William Herschel on December 9, 1784. The cluster was also observed by John Herschel on January 7, 1831. He also observed it on February 5, 1837, identifying it as a different object, which was catalogued as NGC 2520. It is a poor cluster and with no central concentration, with Trumpler class III1p.
NGC 7160 is an open cluster in the constellation Cepheus. It was discovered by William Herschel on November 9, 1789. The cluster was also observed by John Herschel on October 7, 1829. It is a poor cluster and with little central concentration, with Trumpler class II3p. It is part of the stellar association Cepheus OB2, located one degree south-southwest of VV Cephei.
NGC 6910 is an open cluster in the constellation Cygnus. It was discovered by William Herschel on October 17, 1786. The cluster was also observed by John Herschel on September 18, 1828. It is a poor cluster with prominent central concentration and Trumpler class I2p. NGC 6910 is the core cluster of the stellar association Cygnus OB9.