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We study spectral lines in exceptionally bright solar limb prominences withpronounced sodium and magnesium emission. We find that most prominences withsignificant NaD2 and Mgb2 emission show centrally reversed profiles of H-alphaand occasionally even of H-beta, which are are well reproduced by semi-infinitemodels. The maximum H-alpha source function corresponds to an excitationtemperature of 3950 K, for pronounced central reversions 4000 K; the relatedoptical thickness exceeds 10.0. The narrow widths of the NaD2 and Mgb2 profilesyield a non-thermal broadening of 5 km/s.

Solar prominences with Na and Mg emissions and centrally reversed Balmer line