You observe three different star clusters and find that the main-sequence turnoff stars in Cluster 1 have spectral type F, the main-sequence turnoff stars in Cluster 2 have spectral type A, and the main-sequence turnoff stars in Cluster 3 have spectral type G. Which star cluster is the youngest and which one is the oldest

D

Question:

You observed three different star clusters and found that the main-sequence turnoff stars in cluster 1 had spectral type A, the main-sequence turnoff stars in cluster 2 had spectral type B, and the main-sequence turnoff stars in cluster 3 had spectral type G. Which star cluster is the oldest?

A.) cluster 1

B.) It is impossible to determine their ages given only the spectral types

C.) cluster 2

D.) cluster 3

Explanation:

the answer to this question is option D, Cluster 3

the farther a star cluster gets away from where they are were born the easier it is to estimate how old they are based of the spectral type they are coded with using the HR diagram

Also, the spectral sequence O, B, A, F, G, K, M is the sequence of temperatures where beginning with letter O being the Hottest and letter M being the coolest. Younger Star clusters are hotter while cooler star clusters are older