Ionization memory of plasma emitters in a solar prominence

Aims. In the low-collisional, partially ionized plasma (PIP) of solar prominences, uncharged emitters might show different signatures of magnetic line broadening than charged emitters. We investigate if the widths of weak metal emissions in prominences exceed the thermal line broadening by a different amount for charged and for uncharged emitters. Methods. We simultaneously observe five optically thin, weak metal lines in the brightness center of a quiescent prominence and compare their observed widths with the thermal broadening. Results. The inferred nonthermal broadening of the metal lines does not indicate systematic differences between the uncharged Mg b2 and Na D1 and the charged Fe <ns0:sc>II</ns0:sc> emitters, only Sr <ns0:sc>II</ns0:sc> is broader. Conclusions. The additional line broadening of charged emitters can reasonably be attributed to magnetic forces. That of uncharged emitters can then come from their temporary state as ions before recombination. Magnetically induced velocities will be retained some time after recombination. Modelling PIPs then requires consideration of a memory of previous ionization states.