Galactic Star Clusters
In the spiral arms enormous numbers of star groups, clusters and associations are formed during the youngest history of our galaxy. Some of them measuring over 100 light years in extent and contain thousands of stars of different sizes and color. Many of them are embedded in glowing nebulosity or great dark clouds of cosmic dusk. All these star clusters are examples of one type, the "Galactic" or "Open" star clusters, so called because of their scattered appearance and the fact that they are found inside the galaxy, along the spiral arms. The galactic star clusters are classified according to below "Trumpler" codes for concentration, range in brightness, richness.
| Concentration | Range in brightness |
Richness |
| I. | Detached, strong concentration toward the center |
1. | Small range | p. | Poor (<50 stars) |
| II. | Detached, weak concentration toward the center |
2. | Moderate range | m. | Moderately rich (50-100 stars) |
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| III. | Detached, no concentration toward the center |
3. | Large range | r. | Rich (>100 stars) |
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| IV. | Not well detached from surrounding star field |
An "n" following the Trumpler classification denotes nebulosity in the galactic star cluster.
If you have never dealt with these classifications before, perhaps below example will help.
| M45 : |
classification |
---> |
I,3,r,n |
|
discription |
---> |
Rich cluster (>100 stars) with a large rang in brightness. Detached from the surrounding star field and with a strong concentration toward the center.
Embedded in nebulosity. |
Click on below thumbnails to go to the related page.
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| Cr399 |
M29 (NGC6913) |
M34 (NGC1039) |
M35 (NGC2168) |
M37 (NGC2099) |
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| M38 (NGC1912) |
M39 (NGC7092) |
M44 (NGC2632) |
M45 |
M52 (NGC7654) |
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| M67 (NGC2682) |
NGC206 |
NGC869 / 884 |
NGC1893 |
NGC2244 |
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| NGC6871 |
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© Copyright Rob Kantelberg
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