Tuesday, September 4, 2012

Globular Cluster Photo Series (Part 23): NGC 6356

Well. This is a first. Today's globular cluster is the first one I've showcased here on my blog that doesn't have an article about it on Wikipedia. I don't use Wikipedia for all my information but it does make a nice central repository of info, so I had to do a little more digging around tonight. This sort of thing will probably start happening more and more as I exhaust the Messier objects and the brighter or more famous NGC ones. (I already talked a bit about the New General Catalogue in my post about NGC 3201, the first NGC globular cluster I showcased back in March.)

Anyway, NGC 6356. It's located in the constellation Ophiucus at the rather large distance of 49,200 light-years from us. At this distance, I calculate its diameter to be about 115 light-years (since I couldn't find a number anywhere) given its size of about 8.0 arc-minutes on the sky (full Moon is about 30). This would actually make it among the larger clusters of the Milky Way, but its great distance makes it appear small (though it's still among the top 50% of clusters by area on the sky).

NGC 6356 in Ophiucus.

NGC 6356 is also located pretty far from the galactic core outside the galactic plane, at about 24,400 light-years (that's about a quarter of the way across the entire Milky Way galaxy). Most globular clusters are closer to the core (and disk) of the galaxy.

Another interesting thing about NGC 6356 is that it is located about 80 arc-minutes from another globular cluster, Messier 9 (which I wrote about on August 5th). That distance is small enough that I could actually catch both clusters in one picture with a well-placed shot, though I didn't know about it until tonight. Once I found out, however, I was able to match up star patterns seen in both pictures and put them together to make the picture below. Messier 9 is the cluster on the left, while NGC 6356 is the one on the right.

Messier 9 (left) and NGC 6356 (right) in Ophiucus.

While looking at this picture, keep in mind that M9 is about 90 light-years across while NGC 6356 is about 115; it's only NGC 6356's greater distance that makes it look about the same size. Also, since this is two pictures reduced and composited separately, the brightness scale between them is not uniform.

So, all in all NGC 6356 turns out to be a rather interesting cluster for an object not interesting enough to have a Wikipedia page. A hui hou!

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