Caldwell 14 - Double Star Cluster in Perseus

Visible to the naked eye from a dark location, Caldwell 14 is popularly known as the Double Cluster in Perseus. These two bright open star clusters, also called NGC 869 and NGC 884, appear side by side, about halfway between the bright stars in the constellations Perseus and Cassiopeia. Located about 7,500 light-years away, the clusters contain hundreds of hot, young stars that cause the clusters to shine brightly in our sky. To the naked eye, the two clusters look like one large hazy patch, but binoculars or telescopes neatly split the pair, providing beautiful views of this celestial treasure. The Double Cluster appears highest for Northern Hemisphere observers during the late fall or early winter. 

I took the images that make up this photo the night of January 5th, 2023 - a 100% full moon night. I used an OPT L-Pro broadband filter to help with it, and the glow of the towns north of me. It is comprised of 116 60s exposures, or just shy of 2 hrs of exposure.  

Open clusters are believed to originate in the same general area of space, from the same local gas clouds. Due to their age similarities, it is likely that both NGC 884 and NGC 869 were a product of the same star-forming region in Cepheus.

Based on their individual stars, the clusters are relatively young.  NGC 869 is 5.6 million years old and NGC 884 is 3.2 million years old, making them among the youngest star clusters known in the galaxy.  In comparison, the Pleiades (M 45) have an estimated age ranging from 75 million years to 150 million years.  The Double Cluster was charted by skywatchers as early as 150 B.C. Hipparchus saw it, and Ptolemy named it as one of seven “nebulosities” in the Almagest, an ancient astronomy text used for over a millennium. The true nature of the Double Cluster wasn’t discovered until the invention of the telescope many centuries later. In the early 19th century William Herschel was the first to recognize the object as two separate star clusters.  This image is taken at a focal length of 840mm and are easily distinguishable as two separate open star clusters.  

Personally, I always thought stars were fixed in space.  Our paradigm of time and distance are very limited.  Turns out everything in space is moving.  Those items gravitationally bound to each other move together.  There are more than 300 blue-white super-giant stars in each of the clusters. The clusters are also blueshifted, with NGC 869 approaching Earth at a speed of 39 km/s (24 mi/s) and NGC 884 approaching at a similar speed of 38 km/s (24 mi/s).  Not to worry though, by the time they arrive, earth will be gone.

Another fun fact is that space is not black. There's this stuff called IFN, or Integrated Flux Nebula.  It's the reddish gas seen subtly in the haze of the background as it reflects the light of all of the stars in the Milky Way.  Most photographers darken it out so it doesn't distract from the focal point of the image. In most images I find it lends depth and a bit of realism. In others, not so much. 

The star colors amaze me and is what draws me to photograph these clusters!  I love the blue hues of the massively bright young stars.  The contrast provided by the few red giants and the main sequence stars, which look orange or yellow, provides not only depth but a bit of a twinkle to the image.  As we continue our seasonal tilt away from the perseus arm of the milky way, galaxy season for photographers will prevail and many star clusters, galaxy clusters, and globular clusters will emerge from the depths of space.

I hope you enjoy.