NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster (Mirosław Stygar)

Celestial hemisphere: Northern · Constellation: Perseus (Per) · Contains: 7 Per) · NGC 869 · NGC 884 · The star 10 Per · The star 8 Per · The star Misam al Thurayya I (χ Per · chi Persei Cluster · h Persei Cluster

NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster, Mirosław Stygar

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NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster

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NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster

The frame features the well-known and popular Double Cluster, composed of two open clusters NGC 869 and NGC 884. Conventionally, both clusters are referred to as h Persei and χ (chi) Persei respectively. The use of Greek letters - h Persei and χ Persei - first appeared in the Uranometria published in 1603, the atlas of the astronomer Johann Bayer.

The Double Cluster h & χ was consciously observed even in ancient times. It was cataloged by the Greek astronomer Hipparchus as early as 130 BCE. Bedouin Arabs saw in it the tail of the smaller of two fish they visualized in this area, and it was depicted in illustrations in Abd al-Rahman al-Sufi's Book of Fixed Stars.

Both components of the cluster are visible to the naked eye (their size in the sky is about 20'/25', with a brightness of 5.3-6.1 mag.) and lie at a distance of about 7500 light-years in the Perseus Arm.

NGC 869 has a mass of 4700 solar masses, and NGC 884 has 3700 solar masses. Both clusters are surrounded by a very extensive halo of stars, with a total mass of at least 20,000 solar masses for the entire complex. They form the core of the OB1 stellar association in Perseus - clusters of young and hot stars. Based on the spectroscopic analysis of stars in both clusters, it has been determined that both clusters are relatively young, about 14 million years old. Each cluster contains over 300 blue giants, making the entire Double Cluster h & χ a beautiful and extremely photogenic object, enjoyable in visual observations as well as attractive in astrophotography.

Poland

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NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster

NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster

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NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster

NGC 869 & NGC 884 - The H and χ (Chi) Persei Double Cluster

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