--------------------------------------------------------------- UPDATE OF JOP9 (as of September 1999) --------------------------- "Plasma Diagnostics and Dynamics" Vial, J.-C.(1), Bocchialini, K.(1), Madjarska, M. S.(2) (1) Institut d'Astrophysique Spatiale, Bat. 121, Universite Paris XI/CNRS, 91405 Orsay, France (2) Institute of Astronomy, 72, Tzarigradsko chaussee Blvd., 1784 Sofia, Bulgaria A) Scientific background --------------------- One subject of fundamental importance for Solar Physics is the true nature of Solar Prominences (one hundred times cooler and denser than the surrounding coronal material). The purpose of the proposed observing programme is a spectroscopic plasma diagnostics - evaluation of the main plasma parameters like density, temperature, and velocities of both the cool prominence material and prominence-corona transition region. Using SUMER observations, Wiik et al. (1997, Solar Phys., 175, 411) derived (by the emission lines intensity ratio O IV 1401.16/1399.76) in a number of different prominence structures electron densities which range from 3 10^9 up to 3 10^11 cm^{-3}. Recently, Madjarska et al. (1999, ESA SP-446 (SOHO-8 Proc.)) obtained at two different places on the prominence body, an electron density ranging from 1.3 10^9 to 1.4 10^{10} cm^{-3} (the corresponding electron pressure ranges from 0.03 to 0.31 dyn cm^{-2}). These plasma parameters are the basis of the theoretical models developed, and aiming to explain the formation, stability, and final disappearance of solar prominences, as well as advance a further improvement of these models. Using the observational data taken by EIT, SUMER and CDS/SOHO we could verify the proposed by Nenonvski et al. (1998, in D. Webb, D. Rust, B. Schmieder (eds.) IAU Coll. 167, ASP Conf. Series, v. 150, p. 354.) mechanism of field-aligned currents intensification, which might provoke the observed quiescent prominence destabilization. On one hand, the aim of this joint observing programme is to confirm and enrich the results obtained so far. On the other hand, by running simultaneous observations with both SUMER and CDS spectrometers and the EIT imager we could trace both the temporal evolution, and the corresponding changes in the plasma parameters of prominences undergoing a process of destabilization. B) Proposed observations ------------------------ SUMER 1st sequence: (context image) Slit: 1"x120" Area: 120"x120" Lines: He I (584.33 A) Location: solar prominence Exposure Time: 10s Step: 2 x 0.76" Step number: 80 Duration: 15 minutes 2nd sequence: Slit selection: 0.3" x 120" Lines: Si IV (1393.76 A), Si IV (1402.77 A), O IV (1399.76 A), O IV (1401.16 A) Exposure Time: 12 s Duration: 3 hours Rotation compensation: usual CDS: 1st sequence: context Sequence name: EJECT_V3/v18 Area: 240" x 240" Lines: He I (584.33 A), O V (629.73 A), Mg IX (368.06 A), Si X (347.40 A), Si X (365.04 A), Fe XVI (360.76 A) Location: same as SUMER in a solar prominence Exposure Time: 15 s Duration: 15 minutes 2nd sequence: Sequence name: EJECT_V3/v42 Area: 240" x 240" Lines: Fe XVI (306.76 A), Mg IX (368.06 A), Ca X (557.57 A), Ne VI (552.77 A), He I (584.33 A), O V (629.73 A) Location: same as SUMER in a solar prominence Exposure Time: 15 s Duration: 3 hours ----------------------------------------------------------------------------------