Messier 14 (M14) is a globular cluster (a large compact spherical star cluster, typically of old stars in the outer regions of a galaxy) located in the southern constellation Ophiuchus.
If you compare it to other globular clusters (e.g. M13 or M5), you will notice that many of the stars here have a distinct yellow color. The reason for that is it’s age. Its estimated age is about 13 billion years and most of its stars are not hot enough. The bluer the star, the hotter is and the colder stars are toward the yellower-redder part of the spectrum. This cluster is clearly full of old, colder stars. Also, cluster has only about 5 percent of the Sun’s heavy elements, which also points to its age.
The cluster lies at a distance of 30,300 light years from Earth, has an apparent magnitude of 7.6 and contains about 150,000 stars. It occupies an area about 100 light years across in size. M14 can easily be seen in binoculars, but is not visible to the naked eye. The brightest star in the cluster has a visual magnitude of 14 and the average apparent magnitude of the cluster’s 25 brightest stars is 15.44.
I took this image a little over 5 hours. (Luminance 37 images of 5 minute each and 14 images of 3 minutes each for each of RGB colors).