Trumpler Classification for Open Star Clusters

Question 1

Concentration

Answer 1

I. Detarched - strong concentration of stars towards the center.
II. Detached - weak concentration of stars toward the center.
III. Detached - no concentration of stars toward the center.
IV. Poor detachment from background star field.

Question 2

Range of Brightness

Answer 2

1: Small range
2: Moderate range
3Large range

Question 3

Richness of Cluster

Answer 3

p-Poor (< 50 stars)
m-Moderate (50-100 stars)
r-Rich (> 100 stars)
n-Cluster with nebulosity