Astro Imaging & Dark Sky Preserve
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The Double Cluster is thought to be some 7,500 light-years distant, and to be separated from one another by a few hundred light-years. It’s amazing that we can see these stars at all across this great span of space. We know they must be bright stars, intrinsically, or we wouldn’t be able to see them. Each cluster contains a few hundred stars, and, indeed, these stars are young, hot supergiant suns that are many thousands of times more luminous than our sun.
Astronomers tell us that the Double Cluster lies within the Perseus arm of the Milky Way galaxy. However, our solar system resides in the inner part of the Orion arm. Therefore, when we look at the Double Cluster, we are looking through our local spiral arm and all the way to the next spiral arm outward from the galactic center.
The two star clusters making up the Double Cluster are called NGC 869 (h Persei) and NGC 884 (Chi Persei).