Double Cluster
| Double Cluster | |
|---|---|
| Apparent magnitude (V) | 3.7 and 3.8 |
| Apparent dimensions (V) | 60′ |
| Physical characteristics | |
| Other designations | Caldwell 14 |
| Associations | |
| Constellation | Perseus |
The Double Cluster (also known as Caldwell 14) consists of the open clusters NGC 869 and NGC 884 (often designated h Persei and χ (chi) Persei, respectively), which are close together in the constellation Perseus. Both visible with the naked eye, NGC 869 and NGC 884 lie at a distance of about 7,500 light years in the Perseus Arm of the Milky Way galaxy.[2]
Membership
NGC 869 has a mass of 4,700 solar masses and NGC 884 weighs in at 3,700 solar masses; both clusters are surrounded with a very extensive halo of stars, with a total mass for the complex of at least 20,000 solar masses.[1] They form the core of the Perseus OB1 association of young hot stars.[2]
Based on their individual stars, the clusters are relatively young, both 14 million years old.[1] In comparison, the Pleiades have an estimated age ranging from 75 million years to 150 million years.
There are more than 300 blue-white super-giant stars in each of the clusters. The clusters are also
History
Greek astronomer
The clusters were designated h Persei and χ Persei by Johann Bayer in his Uranometria (1603).[7] It is sometimes claimed that Bayer did not resolve the pair into two patches of nebulosity, and that χ refers to the Double Cluster and h to a nearby star.[8] Bayer's Uranometria chart for Perseus does not show them as nebulous objects, but his chart for Cassiopeia does, and they are described as Nebulosa Duplex in Schiller's Coelum Stellatum Christianum, which was assembled with Bayer's help.[9]
Location
The Double Cluster is circumpolar (continuously above the horizon) from most northern temperate latitudes. It is in proximity to the constellation Cassiopeia. This northern location renders this object invisible from locations south of about 30º south latitude, such as New Zealand, most of Australia and South Africa. The Double Cluster is approximately the radiant of the Perseid meteor shower, which peaks annually around August 12 or 13. Although easy to locate in the northern sky, observing the Double Cluster in its two parts requires optical aid. They are described as being an "awe-inspiring" and "breathtaking" sight, and are often cited as a target in astronomy observer's guides.[10]
Mythology
Perseus was a famous hero of Greek mythology, a son of the Greek god Zeus. Along with beheading Medusa, Perseus performed other heroic deeds such as saving princess Andromeda who was chained to a rock as a sacrifice to a sea monster, Cetus. The gods commemorated Perseus by placing him among the stars, with the head of Medusa in one hand and the jeweled sword in the other. The Double Cluster represents the jeweled handle of his sword.[11]
References
- ^ S2CID 16454332.
- ^ doi:10.1086/321139.
- S2CID 9079873.
- ^ Ridpath, Ian. Star Tales – Andromeda Galaxy and the Double Cluster in al-Sufi's Book of the Fixed Stars. Online edition. Retrieved 2021-09-19.
- ISBN 978-0-521-82796-6.
- ^ "Introduction". Caldwell Club. astroleague.org. Retrieved 8 September 2006.
- ^ Ridpath, Ian. Star Tales – The Double Cluster. Online edition. Retrieved 2024-02-24.
- ^ O'Meara, Stephen James; Green, Daniel W.E. (February 2003). "The mystery of the Double Cluster". Sky and Telescope. Vol. 105, no. 2. pp. 116–119.
- ISBN 0939923785.
- ^ Chaple, Glenn (January 2011). "A double take". Astronomy. Vol. 39, no. 1.
- ^ Ridpath, Ian. Star Tales – Perseus. Online edition. Retrieved 2021-09-19.
External links
- "Double Cluster". SEDS.
- "Double Cluster". AstroPhoto.net. Archived from the original on 2007-08-20.
- "Perseus Double Cluster". Dark Atmospheres Photography.
- "The Double Cluster". Astronomy Picture of the Day. NASA. 4 December 2009.
- Double Cluster on
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