Barczynski, K., Schmieder, B., Gelly, B., Peat, A. W. and Labrosse, N. (2023) Two-horn quiescent prominence observed in Hα and Mg II h&k lines with THEMIS and IRIS. Astronomy and Astrophysics, 680, A63. (doi: 10.1051/0004-6361/202345970)
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Abstract
Context. Prominences are large magnetic structures in the corona filled by cool plasma with fast evolving fine structure. Aims. We aim to better understand the plasma conditions in the fine structure of a quiescent prominence including two transient horns observed at the bottom of the cavity using the high resolution Interface Region Imaging Spectrograph (IRIS) and the MulTi-Raies (MTR) spectrograph of the Télescope Heliographique pour l’Etude du Magnétisme et des Instabilités Solaires (THEMIS) in the Canary Islands. Methods. We analysed the spectra obtained in Hα by THEMIS and Mg II by IRIS and compare them with a grid of 23 940 1D radiative transfer models which include a prominence-to-corona transition region (PCTR). The full observed profiles of Mg II in each pixel are fitted completely by synthesised profiles with ×RMS (Cross RMS; an improved version of the rolling root mean square (rRMS) method). When the RMS is below a certain threshold value, we recover the plasma conditions from the parameters of the model best fitting the observed line profile. This criterion is met in two regions (the horns and edge of the prominence) where the line profiles can generally be described as single peaked. Results. The 1D models suggest that two different kinds of model atmospheres correspond to these two regions. The region at the edge is found to be fitted mainly with isothermal and isobaric models, while the other area (the horns) is seen to be fitted with models with a PCTR that have optical thicknesses of less than 5. In the prominence edge, the theoretical relationship between the integrated intensities in Hα and Mg II is verified and corresponds to low emission measure values. In these regions the electron density is around 1010 cm−3, while it is one order of magnitude less in the horn regions around 109 cm−3. Conclusions. In the horns, we find some profiles are best fitted with models with high mean temperatures. This suggests that the hot PCTR found in the horns could be interpreted as prominence plasma in condensation phase at the bottom of the coronal cavity.
| Item Type: | Articles |
|---|---|
| Additional Information: | This study benefited from financial support from the Programme National Soleil Terre (PNST) of the CNRS/INSU, as well as from the Programme des Investissements d’Avenir (PIA) supervised by the ANR. Support from STFC grants ST/S505390/1 (AWP) and ST/T000422/1 (NL) is gratefully acknowledged. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Schmieder, Prof Brigitte and Peat, Dr Aaron and Labrosse, Dr Nicolas |
| Authors: | Barczynski, K., Schmieder, B., Gelly, B., Peat, A. W., and Labrosse, N. |
| College/School: | College of Science and Engineering > School of Physics and Astronomy |
| Journal Name: | Astronomy and Astrophysics |
| Publisher: | EDP Sciences |
| ISSN: | 0004-6361 |
| ISSN (Online): | 1432-0746 |
| Published Online: | 12 December 2023 |
| Copyright Holders: | Copyright © The Authors 2023 |
| First Published: | First published in Astronomy and Astrophysics 680:A63 |
| Publisher Policy: | Reproduced under a Creative Commons licence |
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