Talk:Open cluster

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Contents 1 relation between open and globular clusters? 2 star formation and other statements 3 potential additions to the article 4 TOC layout 5 Is this for real?

[edit] relation between open and globular clusters?

The article treats open and globular clusters as completely separate types, yet according to one of the external links, "some researchers have recently suggested that both types of clusters could be better described as a single continuum of objects". By implication this isn't yet an accepted theory so doesn't need a strong mention, but shouldn't some comment be made about it? The reference given strongly suggests that the only difference may be age (I guess older clusters have to be bigger to stay together and to be seen?). Mozzerati 15:49, 2005 May 8 (UTC)

I've added a bit about the relationship between opens and globulars, which I hope addresses this point. Worldtraveller 20:21, 8 May 2005 (UTC)

There's a general article on star clusters that also covers stellar associations. I think that page addresses the issue. Thanks. — RJH (talk) 17:10, 11 January 2007 (UTC)

[edit] star formation and other statements

This article states that "All stars are originally formed in multiple systems." and yet the star formation article doesn't mention that and also papers that I have (just) read instead state that "truly isolated star formation may therefore be a rare phenomenon, and even in low-density regions, most stars may form in groups [...]" (Larson). What rules out the possibility of a single star forming and the rest of the gas present failing to form another object? Possibly in the presence of gravitationally attrictive non star forming mass (dark matter??)? Or would that count as a "multiple system"?

I might have been a bit strong with the wording there. I guess as a scientist I should occasionally stick with a vague wording, like virtually all. It's my understanding, though, that only a cloud of gas with several hundred solar masses or more will ever collapse under its own gravity, but the mechanics of star formation mean it will always fragment into smaller chunks. A cloud of gas small enough to form just one star would not collapse under gravity; a cloud of gas large enough to collapse would always fragment into many chunks, ranging in mass from brown dwarf size to up to 100 solar masses, but I think it would be impossible to form one stellar object and thousands of non-stellar ones. I'll try and expand that section of the article to explain it fully. Worldtraveller 20:21, 8 May 2005 (UTC)

"the stellar density in open clusters is much lower than that in open clusters" - I guess that my italics should read "globular" Mozzerati 16:28, 2005 May 8 (UTC)

Indeed - corrected it now :) Worldtraveller 20:21, 8 May 2005 (UTC)

[edit] potential additions to the article

A nice thing to add to the article would be a bit more history of research on open clusters. Who named them? At what point was their importance in measuring distance suggested?

I have an excellent book about the history of the study of 'nebulous' objects, but I lent it to someone about four years ago and haven't seen it since. If I ever get it back off them I could probably flesh out the history a lot more, but in the meantime, if anyone else has a copy of The Search For The Nebulae by Kenneth Glyn Jones... :)Worldtraveller

[edit] TOC layout

I'm not sure I like the right-aligned TOC - I think it makes the top of the article look very cluttered, with the different-sized boxes for the image and TOC somewhat jarring on the eye. Default TOC gives a lot of whitespace but on balance I prefer it - what does anyone else think? Worldtraveller 14:35, 29 July 2005 (UTC)

I do not like {{TOCright}} - the TOC is something that should be standardised by default and fixed in CSS or whatever. I have filled the whitespace with the lead Pleiades image (but another one could be added, if you like).-- ALoan (Talk) 19:08, 29 July 2005 (UTC)

[edit] Is this for real?

Italics are mine:

"Another view to cluster formation is that they form rapidly out of a contracting molecular cloud core and once the massive stars begin to shine they expel the residual gas with the sound speed of the hot ionised gas. From the time of start of cloud-core contraction to gas expulsion takes typically not more than one to three million years. As only 30 to 40 per cent of the gas in the cloud core forms stars, the process of residual gas expulsion is highly damaging to the cluster which loses many and perhaps all of its stars [6]. All clusters thus suffer significant infant weight loss, while a large fraction undergo infant mortality. The young stars so released from their natal cluster become part of the Galactic field population. Because most if not all stars form clustered, star clusters are to be viewed the fundamental building blocks of galaxies. The violent gas-expulsion events that shape and destroy many star clusters at birth leave their imprint in the morphological and kinematical structures of galaxies [7]."

Is this simply poor English or the goofy work of a vandal? I've never read anything like this in an astronomy textbook. 68Kustom (talk) 07:03, 5 May 2008 (UTC)