Plate 3: Luminosity Effects at O6

Star Index

Plate 3: Luminosity Effects at O6

We use the procedure followed by Botto and Hack (Contr. Milan–Merate Obs., No. 194, 1962) for the classification of O stars by means of the intensity of Hγ (luminosity class), and the ratio of lines of He I to He II (spectral type). Strong positive luminosity effects are shown at O6 by N IV 3479–85 (absorption), and by the emission lines N III 4634–42 and He II 4686; the latter changes to a strong absorption line at O6 V. The detailed classification of Walborn has been of great value to theoretical investigations.

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