NGC 752 - A View from a City
NGC 752 - A View from the City
NGC 752 or Caldwell 28 lies well within Andromeda's borders, just a few degrees southwest of the spectacular double star, Gamma Andromeadea.
Amidst the splendor and easy attraction of Andromeda’s galaxies, NGC 752 is an often overlooked but beautiful open cluster and will no doubt be a pleasure to contemplate through binoculars or a low-magnification eyepiece.
What I saw at 40x in the f/10 overfilled my field of view; four dozen and more sparkling gems scattered across space with a star magnitude ranging from the very bright at about 8 magnitude to the barely visible. The cluster not only overfills the field of view but also the imagination; the place where stargazing really takes off. It’s about 1,300 light years away with an age of over 2,000 million years old (English speakers may prefer to say, 2 billion years old), which makes it one of the oldest visible open clusters in the Milky Way.
This cosmic age is clearly visible in the subtle colouring of the cluster’s stars. Relatively young clusters such as Pleiades, which is probably no more than a 100 million years old, consists of mostly young, bright and beautiful blue-white stars, whereas in NGC 752, you can clearly see that many have evolved into main sequence red-giants.
Over a few nights with the aid of the Micro Guide eyepiece, I tried to estimate the size of just one of the little red gems (the middle star of the triangle at the bottom left of the sketch at about 7 o'clock) and noted that it appeared to measure somewhere between 600 to 800 million kilometers in diameter, clearly equalling the enormity and splendor of Antares or Betelgeuse.
It is not only the colour of the stars that give away NGC 752’s age. It is also shown in the way the cluster is so spread-out. As it circles the Milky Way, the gravitation of other huge objects like stars and massive dust clouds tug and pull at the cluster, gradually wearing away and weakening its own mutual attraction. No doubt a few billion years ago, NGC 752 was as spectacular as any of Messier’s popular globular clusters; today it remains a relative secret.
The sketch itself was drawn in the city with a black pen on white paper at 40 magnification. Back at home, I tidied the sketch and added colour which had been coded on site.
The Tal 100rs, a 25mm X-Cel LX EP, the CG-5 and a pirate's eye patch were used as tools of trade. Compromised by my field of view, the given sketch hardly does the cluster justice but I had to choose what I considered the best point of view and get on with it.
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