Irregular Galaxies and Star Clusters

[worthj1970]

This is probably a really basic question. What is the difference between a dwarf irregular galaxy and a large star cluster?<br /><br />Thanks!<br /><br />John W.

 

[Saiph]

Mostly size, large star clusters are often globular clusters. They consist of old population II stars. They also have a very spherical shape overall. Open clusters don't approach this size.<br /><br />Dwarf Irregulars usually have a higher proportion of younger stars.<br /><br />But that's all I've got. There may be a more academic difference but I haven't heard of it. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[thalion]

Dwarf irregulars are usually rich in gas and dust, and have abundant star formation, along with older stars. An open cluster, even a large and very young one, would be confined to the disk or main body of another galaxy--it would not be an independent entity. It would also consist entirely of young stars, with no older stars.

 

[worthj1970]

I'm fairly certain I read somewhere (space.com?) that large star clusters have been found outside of our galaxy. If so, what would stop them from becoming dwarf irregular galaxies?<br /><br />Thanks!<br /><br />John W.