NGC 6231
MK spectral classification
No
Ref
MK
0346
400
B0 III
0350
400
O9.5 V
0437
400
B0 Vn
0651
400
B1 III
2501
400
B1 Ia
2723
400
B3: V
2724
400
B0: IV/V
2726
400
B1 V
2745
400
B0 V
2749
400
B1.5 V
2769
400
B0.5 V
2774
400
B1: II/III
2810
400
B2 V