Plate 13: Main Sequence B3–A5

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Plate 13: Main Sequence B3–A5

The principal criteria for spectral type between B9.5V and A5V are the intensities of the low–level metallic lines. Among the most useful of these are the broad blends, Mn I 4030–4 and Fe I 4271.

The use of these blends on small–scale spectrograms decreases the possibility of systematic errors between narrow–lined and broad–lined spectra.

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