Celestial hemisphere:  Northern  ·  Constellation: Perseus (Per)  ·  Contains:  Double cluster  ·  NGC 869  ·  NGC 884  ·  The star 7Per  ·  The star 8Per
Double Cluster (Caldwell 14 = NGC 869 & NGC 884), BrettWaller
Double Cluster (Caldwell 14 = NGC 869 & NGC 884)
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Double Cluster (Caldwell 14 = NGC 869 & NGC 884)

Double Cluster (Caldwell 14 = NGC 869 & NGC 884), BrettWaller
Double Cluster (Caldwell 14 = NGC 869 & NGC 884)
Powered byPixInsight

Double Cluster (Caldwell 14 = NGC 869 & NGC 884)

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The famous Double Cluster is the core of the vast Perseus OB1 association of young supergiant and blue stars which surround them. Both clusters are visible to the naked eye under dark skies, and were known to the Greeks as a nebulous star. Open cluster NGC 869, often designated h Persei on older star charts, lies at a distance of 7200 light years and contains 3700 solar masses, while open cluster NGC 884, designated as x Persei, lies at a distance of 7500 light years and contains 2800 solar masses. A study by Currie et al. (2010) found a very extensive halo of stars around the Double Cluster containing an estimated 20,000 solar masses.

While superficially similar at first glance, the two components of the Double Cluster are in fact quite different one from the other. The brightest stars of NGC 869 are early B-giant and supergiant stars, in contrast with the brightest stars of NGC 884 which are mostly white late B or early A, or red M-type, supergiants. The five red supergiant stars of NGC 884 easily distinguish it from its neighbor, and all are variable stars of 8th magnitude designated as RS Persei, AD Persei, FZ Persei, V403 Persei, and V439 Persei. As you might suspect from the presence of red supergiant stars, NGC 884 is the older of the two clusters with an estimated age of 14 million years, as compared to its younger neighbor NGC 869 with an estimated age of "only" 6 million years. Each cluster has a diameter of approximately 60 light years. It is an interesting thought experiment to imagine the spectacular night time vista that would be presented to someone on a planet orbiting any one of the stars in these clusters.

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Double Cluster (Caldwell 14 = NGC 869 & NGC 884), BrettWaller