Plate 21: Luminosity Effects Near A2

Star Index

Plate 21: Luminosity Effects Near A2

The Balmer lines of hydrogen — and the lines of Ti II and Fe II — are very sensitive to differences in luminosity near this spectral type.

A sensitive discriminant in use is the change in appearance of the line–pattern in the range of λλ4383–4584: Mg II 4481 stands out over the numerous singly–ionized metallic lines surrounding it, at luminosity class V; it loses this preeminence on passing toward higher luminosity, and is no longer outstanding at A2 Ia.

Valid XHTML Created by diploma on 27/07/04