%0 Journal Article
%T The Na i and Sr ii Resonance Lines in Solar Prominences
%+ Institut d'Astrophysique de Paris (IAP)
%A Stellmacher, G.
%A Wiehr, E.
%< avec comité de lecture
%J SOLAR PHYSICS
%V 292
%8 2017
%D 2017
%Z 1705.02475
%Z 2017SoPh..292...83S
%R 10.1007/s11207-017-1103-6
%K Prominences
%K models
%K Spectral line
%K broadening
%K Astrophysics - Solar and Stellar Astrophysics
%Z Sciences of the Universe [physics]Journal articles
%X We estimate the electron density, ne, and its spatial variation in quiescent prominences from the observed emission ratio of the resonance lines Na i 5890 Å (D2) and Sr ii 4078 Å. For a bright prominence (τ_{α}≈25) we obtain a mean ne≈2×10^{10} cm^{-3}; for a faint one (τ _{α }≈4) ne≈4×10^{10} cm^{-3} on two consecutive days with moderate internal fluctuation and no systematic variation with height above the solar limb. The thermal and non-thermal contributions to the line broadening, T_{kin} and V_{nth}, required to deduce ne from the emission ratio Na i/Sr ii cannot be unambiguously determined from observed widths of lines from atoms of different mass. The reduced widths, ΔλD/λ0, of Sr ii 4078 Å show an excess over those from Na D2 and Hδ 4101 Å, assuming the same T_{kin} and V_{nth}. We attribute this excess broadening to higher non-thermal broadening induced by interaction of ions with the prominence magnetic field. This is suggested by the finding of higher macro-shifts of Sr ii 4078 Å as compared to those from Na D2.
%G English
%L insu-03747452
%U https://insu.hal.science/insu-03747452
%~ INSU
%~ CNRS
%~ IAP
%~ SORBONNE-UNIVERSITE
%~ SU-INF-2018
%~ SU-SCIENCES
%~ SU-TI
%~ ALLIANCE-SU