IC 2602 (also known as the Southern Pleiades, Theta Carinae Cluster, or Caldwell 102) 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 A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Carina Carina may refer to: Places Australia * Carina, Queensland, a suburb in Brisbane * Carina Heights, Queensland, a suburb in Brisbane * Carina, Victoria, a locality in Mildura Serbia * Carina, Osečina, a village in the Kolubara District ...

. Discovered by

Abbe 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 ...

in 1751 from

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

, the cluster is easily visible to the

unaided 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 ...

, and is one of the nearest star clusters, centred about 149 parsecs (486

light-years 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 1012 ...

) 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 surfa ...

Description

IC 2602 has a total

apparent 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 li ...

of 1.9, and contains about 75 stars. It is the third-brightest open cluster in the sky, following the

Hyades Hyades may refer to: * Hyades (band) *Hyades (mythology) *Hyades (star cluster) The Hyades (; Greek Ὑάδες, also known as Caldwell 41, Collinder 50, or Melotte 25) is the nearest open cluster and one of the best-studied star clusters. Loca ...

and the

Pleiades The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an asterism and an open star cluster containing middle-aged, hot B-type stars in the north-west of the constellation Taurus. At a distance of ...

. Its apparent diameter is about 50

arcminutes A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

. IC 2602 is likely about the same age as the

IC 2391 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 ...

,, which has a

lithium depletion boundary The lithium depletion boundary (LDB) technique is a method proposed for dating open clusters based on a determination of the lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number ...

age of 50 million years old, though the age estimated from its Hertzsprung-Russell diagram is about 13.7 million years. IC 2602 is thought to form part of the Lower

Scorpius–Centaurus association The Scorpius–Centaurus association (sometimes called Sco–Cen or Sco OB2) is the nearest OB association to the Sun. This stellar association is composed of three subgroups (Upper Scorpius, Upper Centaurus–Lupus, and Lower Centaurus–Crux) ...

Components

Theta Carinae θ Carinae, Latinized as Theta Carinae, is a spectroscopic binary star in the southern constellation of Carina. With an apparent visual magnitude of 2.76, it is the brightest star in the open star cluster IC 2602. It marks the northe ...

is the brightest

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

within the open cluster, with the apparent

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 ...

of +2.74. Theta Carinae is part of the asterism known as the

Diamond Cross Carina ( ) is a constellation in the southern sky. Its name is Latin for the keel of a ship, and it was the southern foundation of the larger constellation of Argo Navis (the ship ''Argo'') until it was divided into three pieces, the other two be ...

, which is often mistaken for the Southern Cross asterism in the constellation of

Crux Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for c ...

. 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, including

HR 4196 V518 Carinae (HR 4196) is a naked-eye variable star in the constellation Carina. It is a member of the bright open cluster IC 2602 near the Carina Nebula. Location V518 Carinae lies in the open cluster IC 2602, 5 arc minutes from its br ...

(V518 Car), HR 4204,

HD 93194 HD 93194 (HR 4205) is a star in the constellation Carina. Its apparent magnitude is 4.79. Its parent cluster is IC 2602 IC 2602 (also known as the Southern Pleiades, Theta Carinae Cluster, or Caldwell 102) is an open cluster in the con ...

, HR 4219, HR 4220,

HR 4222 HD 93607 (HR 4222) is a star in the constellation Carina. Its apparent magnitude is 4.87. Its parent cluster is IC 2602. HD 93607 is a B4 main sequence star, although older spectral studies classified it as a subgiant. It is included ...

, HD 92536, HD 93738, and V364 Carinae.

History

IC 2602 was first discovered by French

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

and

abbot Abbot is an ecclesiastical title given to the male head of a monastery in various Western religious traditions, including Christianity. The office may also be given as an honorary title to a clergyman who is not the head of a monastery. The fem ...

Nicolas-Louis de Lacaille Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a kingdom of France, French astronomer and geodesist who named 14 out of the IAU designated constellations, 88 constellations. From 1750 ...

on March 3, 1751 while in

Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...

. In Lacaille's initial discovery, he classified Theta Carinae (referred as "Theta Navis", or alternatively "Theta Argus") as a third magnitude star, whilst citing the cluster's resemblance to the northern Pleiades.

Observation

Positioned at a

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...

of -64º on the night sky, IC 2602 is most clearly visible from the southern hemisphere, and appears

circumpolar Circumpolar may refer to: * Antarctic region ** Antarctic Circle ** the Antarctic Circumpolar Current ** Subantarctic ** List of Antarctic and subantarctic islands ** Antarctic Convergence ** Antarctic Circumpolar Wave ** Antarctic Ocean * Arctic ...

from southern

subtropics The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north and ...

and

temperate climates In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

; the cluster is observable from a limited selection of north hemispherical regions, mainly

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

areas. IC 2602 is identifiable a few degrees south of the southern

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

, surrounded by various fifth and sixth magnitude stars. To the unaided eye, several faint stars are distinguishable to the east of the blue Theta Carinae.

Notes

References

External links

The Southern Pleaides @ SEDS IC objects pages

{{DEFAULTSORT:IC 2602 Carina (constellation) Open clusters 102b ?