Object name: NGC7788
Designation(s): NGC7788, NGC7790,
NGC 7788 and 7790 right to left. These two small open clusters are located in Cassiopeia and are about 7,700 and 9,600 light-years away respectively. The distance to NGC 7790 is likely more accurate as it contains three Cepheid variable stars which help pin down its 9,600 light-year distance. NGC 7788 is a rather new cluster, probably only about 40 million years old. NGC 7790 is thought to be a bit older at 56 million years old. I've seen speculation the two clusters are related since the distance to NGC 7788 is rather uncertain. But the age difference would seem to rule this out.