Coronal environment of quiescent prominences |
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| Authors: | J E Wiik B Schmieder J C Noëns |
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| Institution: | (1) Observatoire de Paris, Section de Meudon, DASOP, F-92195 Meudon Principal Cedex, France;(2) Observatoires du Pic du Midi et de Toulouse, F-65200 Bagnères-de-Bigorre, France |
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| Abstract: | With thespectro-coronagraph and themultichannel subtractive double pass spectrograph (MSDP) at the Pic du Midi Observatory two quiescent prominences were observed simultaneously. From the spectro-coronagraph observations 2D maps of Hei  10830  , Fexiii 10798 and 10747 line intensities were obtained. In addition, we obtained 2D maps of the ratioR of the two iron lines. This ratio is used as a diagnostic for determining the density of the hot coronal plasma surrounding prominences. We found that the electron density is higher at the location of the prominences than in the corona, whereas small regions ( 40 ) of lower electron density are unevenly distributed around the prominences indicating that the surrounding corona is highly inhomogeneous. The density of the cavity is reduced by a factor 1.5 compared to the density of the prominence environment (5 × 108 cm–3). We discuss the existence of cavities around these prominences according to the orientation of their axes relative to the line of sight and according to the velocity field inside the prominences. Constraints on models for prominence formation are derived. |
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