| IC 2602 | |
|---|---|
.jpg) | |
| Observation data (J2000epoch) | |
| Right ascension | 10h 42m 57.5s[1] |
| Declination | −64° 23′ 39″ |
| Distance | 486 ly[2] (149 pc) |
| Apparent magnitude (V) | 1.9[3] |
| Apparent dimensions (V) | 50′ × 50′ |
| Physical characteristics | |
| Estimated age | 13.7 M.yr−1 |
| Other designations | Theta Carinae Cluster,Caldwell 102,Cr 229,Mel 102, VDBH 103[2] |
| Associations | |
| Constellation | Carina |
| See also:Open cluster,List of open clusters | |
IC 2602 (also known as theSouthern Pleiades,Theta Carinae Cluster, orCaldwell 102)[4] is anopen cluster in theconstellationCarina. Discovered byAbbe Lacaille in 1751 fromSouth Africa,[5] the cluster is easily visible to theunaided eye, and is one of the nearest star clusters, centred about 149 parsecs (486light-years) away fromEarth.
IC 2602 has a totalapparent magnitude of 1.9,[3] and contains about 75 stars. It is the third-brightest open cluster in the sky, following theHyades and thePleiades. Its apparent diameter is about 50arcminutes.
IC 2602 is likely about the same age as theopen clusterIC 2391,[6] which has alithium depletion boundary age of 50 million years old,[7] though the age estimated from itsHertzsprung-Russell diagram is about 13.7 million years.[8] IC 2602 is thought to form part of the LowerScorpius–Centaurus association.[9][10]
Theta Carinae is the brighteststar within the open cluster, with theapparentvisual magnitude of +2.74.[11] Theta Carinae is part of theasterism known as theDiamond Cross, which is often mistaken for the Southern Cross asterism in the constellation ofCrux.
p Carinae (PP Carinae) is another third-magnitude star known to be a member of IC 2602, although it lies well outside the main visible grouping of stars. p Carinae exhibits a variable apparent magnitude ranging from 3.22 to 3.55.
All other members the cluster are of the fifth magnitude and fainter, but several are naked-eye objects, includingHR 4196 (V518 Car), HR 4204,HD 93194, HR 4219, HR 4220,HR 4222, HD 92536, HD 93738, and V364 Carinae.
Anexoplanet has been found orbiting the star TOI-837 in this cluster.[12]
| Designation | Apparent magnitude[13] | Stellar classification[14] | Distance (pc) |
|---|---|---|---|
| Theta Carinae | 2.735 | B0Vp | 142[15] |
| p Carinae (PP Carinae) | 3.247 | B4Vne | 104.645[13] |
| HR 4204 | 5.719 | B3IV/V | 309.598[16][17] |
| HR 4219 | 5.297 | B6Vnn | 156.674[13] |
| HR 4222 | 4.807 | B4V | 154.007[13] |
| HD 92536 | 6.313 | B8V | 156.823[13] |
| HD 93194 | 4.777 | B3/5Vn | 169.146[13] |
| HD 93738 | 8.571 | B9.5V | 417.168[13] |
| V364 Carinae | 5.465 | ApSi | 160.013[13] |
| V518 Carinae | 4.758 | B3V | 140.634[13] |
IC 2602 was first discovered by Frenchastronomer andabbotNicolas-Louis de Lacaille on March 3, 1751 while inCape of Good Hope,South Africa.[18] In Lacaille's initial discovery, he classified Theta Carinae (referred as "Theta Navis", or alternatively "Theta Argus"[citation needed]) as athird magnitude star, whilst citing the cluster's resemblance to the northern Pleiades.
Positioned at adeclination of -64º on the night sky,[19] IC 2602 is most clearly visible from thesouthern hemisphere, and appearscircumpolar from southernsubtropics andtemperate climates; the cluster is observable from a limited selection ofnorth hemispherical regions, mainlytropical areas.[a] IC 2602 is identifiable a few degrees south of the southernMilky Way, surrounded by variousfifth andsixth magnitude stars. To the unaided eye, several faint stars are distinguishable to the east of the blue Theta Carinae.
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