Plate 18: Luminosity Effects at A0

Star Index

Plate 18: Luminosity Effects at A0

The principal criterion for luminosity classification used at A0 here is the progressive widening and strengthening of the hydrogen lines with decreasing luminosity. The A0 V class is divided into A0 Va and A0 Vb. The A0 Vb star has been considered to be a member of the cluster NGC 2516 (AJ., 74, 813, 1969); however, the luminosity indicated by the broad H lines disagrees with that from the cluster HR Diagram.

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