Filament absorption study using THEMIS and SOHO/CDS-SUMER observations

Schmieder, B. and Tziotziou, K. and Heinzel, P. and Malherebe, J.M. and Curdt, W. (2002) Filament absorption study using THEMIS and SOHO/CDS-SUMER observations. Il nuovo cimento C, 25 (5\6). pp. 775-782. ISSN 1826-9885

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A long filament has been observed with THEMIS/MSDP and SOHO/CDS-SUMER, during a coordinated campaign (JOPs 131/95) on May 5, 2000. THEMIS provided 2D Hα spectra, SUMER rasters in the L4 line and spectra of the whole Lymanseries and the Lymancon tinuum, CDS obtained rasters in several EUV lines (e.g., Mg X 624 ˚A, Si XII 520 ˚A, Ca X 557 ˚A and He I 584 ˚A). A large depression of coronal line emission in the CDS images corresponds to the absorption by the hydrogen Lyman continuum and represents the EUV filament. Non-LTE radiative transfer calculations allow to explain, in terms of opacities, the large width of the EUV filament compared to the width of the Hα filament itself. The optical thickness of the Lyman continuum is larger than that of Hα line by one to two orders of magnitude. This could be of great importance in the understanding of the filament formation, if we consider that cool material does exist in filament channels but is optically too thin to be visible in Hα images.

Item Type: Article
Additional Information: Paper presented at the International Meeting on THEMIS and the New Frontiers of Solar Atmosphere Dynamics, Rome, Italy, March 19-21, 2001.
Uncontrolled Keywords: Prominences
Subjects: 500 Scienze naturali e Matematica > 550 Scienze della Terra > 551 Geologia, Idrologia, Meteorologia > 551.5 Meteorologia (Classificare qui l'atmosfera) (Classificare la previsione e le previsioni di specifici fenomeni meteorologici in 551.64; classificare la Micrometeorologia in 551.66) > 551.52 Termodinamica, interazioni atmosferiche con la superficie terrestre, temperature, radiazioni > 551.527 Radiazioni (per fenomeni ottici, vedi 551.565) > 551.5271 Radiazione solare
Depositing User: Marina Spanti
Date Deposited: 12 Mar 2020 17:20
Last Modified: 12 Mar 2020 17:20

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