Service interruption on Monday 11 July from 12:30 to 13:00: all the sites of the CCSD (HAL, EpiSciences, SciencesConf, AureHAL) will be inaccessible (network hardware connection).
Skip to Main content Skip to Navigation
Journal articles

Non-thermal line-broadening in solar prominences

Abstract :
Aims: We show that the line broadening in quiescent solar prominences is mainly due to non-thermal velocities.
Methods: We have simultaneously observed a wide range of optically thin lines in quiescent prominences, selected for bright and narrow Mg b emission without line satellites from macro-shifts.
Results: We find a ratio of reduced widths, ΔλD0, of Hγ and Hδ of 1.05 ± 0.03, which can hardly be attributed to saturation, since both are optically thin for the prominences observed: τγ ≤ 0.3, τδ ≤ 0.15. We confirm the ratio of reduced widths of He 4772 (triplet) and He 5015 (singlet) of 1.1 ± 0.05 at higher significance and detect a width ratio of Mg b2 and Mg 4571 (both from the triplet system) of 1.3 ± 0.1.
Conclusions: The discrepant widths of lines from different atoms, and even from the same atom, cannot be represented by a unique pair [Tkin; Vnth]. Values of Tkin deduced from observed line radiances using models indicate low temperatures down to Tkin ≈ 5000 K. Non-thermal velocities, related to different physical states of the respective emitting prominence region, seem to be the most important line broadening mechanism.
Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03644874
Contributor : Hal Sorbonne Université Gestionnaire Connect in order to contact the contributor
Submitted on : Thursday, April 28, 2022 - 11:00:14 AM
Last modification on : Thursday, April 28, 2022 - 11:01:08 AM

File

aa22781-13.pdf
Publisher files allowed on an open archive

Identifiers

Citation

G. Stellmacher, E. Wiehr. Non-thermal line-broadening in solar prominences. Astronomy & Astrophysics, 2015, 581, ⟨10.1051/0004-6361/201322781⟩. ⟨insu-03644874⟩

Share

Metrics

Record views

7

Files downloads

2