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

¹ Institut d'Astrophysique (CNRS), 98bis Bd. Arago, 75014 Paris, France
² Universitäts-Sternwarte, Geismarlandstraße 11, 37083 Göttingen, Germany e-mail: ewiehr@uni-sw.gwdg.de

Received: 29 June 2004
Accepted: 14 October 2004

Abstract

We observed bright solar limb prominences with significant emission of NaD₂ and Mgb₂ simultaneously with the Hα, Hβ, HeD₃, He⁺4685, and the He^singl 5015 Å lines, using the THEMIS telescope on Tenerife. We find that most prominences with significant NaD₂ and Mgb₂ emissions show pronounced centrally reversed Hα profiles, and occasionally even of Hβ; the strongest emissions reach integrated intensities [ erg/(cm² s str)] . The centrally reversed profiles are well reproduced by semi-infinite models. The source function reaches S [ erg/(cm² s str Å)] corresponding to an excitation temperature  K; here, the optically thickness of Hα amounts . The line widths of the NaD₂, Mgb₂, and HeD₃ profiles yield kinetic temperatures  K and non-thermal broadening  km s^-1.