Star Clusters?

[Manok101]

I've observed two or three star clusters now, two of them, M45, and M44(the one in canis major, please correct me if I got the number wrong) and the one in the middle of cancer (dont know the name for that). What I've noticed is that there are always a few stars just outside of the cluster, sometimes in a little line just outside, are these stars part of the group, or do they too far away to be anything to do with? Or are the clusters really a little bigger than I can see with my viewing conditions?

[Nexus 6]

Hi Manok, well done in finding some star clusters.

I think you have mixed up were they were, don't worry I'm sure we've all done it as a beginner. M44 ( The Beehive Cluster) is in Cancer, you may have found M41 (an open cluster) in Canis Major. I think the stars you are seeing outside the cluster may be just local associates to that region of space but thats just an educated guess, I'm sure someone more knowledgeable than me will explain so. Its best to use as wide a field of view/ low power ep as posssible for open clusters so giving you a nice frame through the ep when observing.

Alan

[brantuk]

Hi Manok. You will find that there are two types of clusters - "globular" clusters and "open" clusters. Many objects do have "chains" of stars trailing from them. I think M11 (Wild Duck) cluster is one of them if I remember correctly - with the Markov chain. (feel free to look them up and correct me as I'm a tad dozy till I've had morning coffee lol).

M13 is a good example of a globular, and the Pliedes (M45) is a good example of an open cluster (both without chains).

[Manok101]

Thanks. Are there two clusters in Canis Major? One time I viewed the cluster it appeared to be globular, but every time since then its been open. I also thought I saw it in a slightly different part of the sky.

[pbyrne]

M41 is the main cluster, there are a number of smaller clusters such as NGC 2360 and NGC 2354, but that's in the south of the constellation. There are some excellent clusters in neighbouring Puppis that are worth checking out such as M46, M47 and M93.

[Manok101]

Well the one i saw last night looked like a half globular, the first time i thought i saw it it looked very circular, with a red star in the middle, or near middle, this one was just half a circle with stars, and I couldn't really see a red dot in the middle. This one last night was like I described kind of a half circle with stray stars around it, could count about 20 stars, but the conditions here aren't that dark, so I just assumed it was poor visibility or something. I have another question about open clusters, are they sometimes in a circle shape like globulars but not as dense?

[cotterless45]

MMMmm, these clusters are held together by gravity. The open clusters are areas of new stars and found on the arms of our galaxy (Milky Way). The globular clusters are ancient stars which are found above and below the central bulge of our galaxy. Seeing as our planet is on one side we are ideally placed to see clusters.

Theories suggest that the arms of the galaxy may sweep up and capture material to make stars and that the globular clusters may have been captured.Remember these are ancient and probably massive stars.They've been around a long time and gravity has held them together as a group.

If you look at M13 in particular it is very rounded. However if you look at the Auriga set you can see dark " dust lanes" through them.

I suppose that gravity would eventually lead to more rounded objects.

That apart, they are worth seeking out for their sparkling beauty.

[bish]

Sorry for not answering your question but if you get a chance find a decent book on the Messiers. It's by no means a complete list but a good place to start. I've got the one by James O'Meara. It will give you plenty more to find and loads of information on what you can expect to see, estimated stars in the cluster, estimated distance etc.