2012 July 16 at 17:23

Ancient open cluster in Lyra

Greek astrophotographer Anthony Ayiomamitis recently imaged the old open cluster NGC 6791 in Lyra. He writes:

"NGC 6791 is not only well-known but also well-studied, for it is one of the oldest open clusters discovered so far and whose age has been estimated to be as high as 10.2 billion years-old (2004 study) and which would make it more than twice the age of the solar system.

"A recent study using HST images revelead three sets of member stars comprised of white dwarfs aged 4 and 6 billion years-old whereas the third (non-dwarf) group was determined to be 8 billion years-old.

"Anyone who has tried to image NGC 6791 knows very well how dim this open cluster is and the difficulty involved in getting it to stand out from the background sky. NGC 6791 is comprised of 10,000 member stars and lies 13,300 light-years away.

"Another open cluster with a very similar storyline is NGC 188 near the northern polar region and which I also plan to revisit over the next few days."

Anthony's image is the result of a total of three hours of exposure; it can be enjoyed in high resolution at http://www.perseus.gr/Astro-DSO-NGC-6791.htm.

NGC 6791, imaged by Anthony Ayiomamitis.