Scientific Justification
The information contained in a spectral atlas is of prime importance to determine as many physical parameters of the observed structure as possible with the smallest uncertainties.
These physical conditions determine the slow evolution of prominences and the instabilities which lead to their eruptions, in some cases to Coronal Mass Ejections in the context of space weather.
Parenti at al. 2005a built a FUV spectra atlas of a quiescent prominence and QS using the SUMER spectrometer in the waveband 800-1250 Å (detector A). They derived non-thermal velocities (NTV), Differential Emission Measure and pressure (Parenti & Vial 2007), which were used to investigate the energy balance. Parenti at al. 2005b also derived the electron temperature from the H I Ly-continuum. Vial et al 2007 investigated the H I Lya/Lyß ratio showing its
potentiality to diagnose geometrical and thermodynamic properties of prominences. Labrosse et al. 2007 studied the effect of radial motions of an erupting prominence on the He resonance lines to investigate the diagnostic possibilities using SOHO and Hinode.
The results achieved until now require further coordinated investigations aiming at the following specific targets:
* Extending the existing atlas of quiescent prominence over a larger range of temperatures and a consequently a larger waveband
* Building a dedicated atlas for an activated prominence
These results will be of great importance to contribute to several issues raised by these authors:
- To quantify and model the H I and He I continuum absorption in the EUV-UV emissions.
- To better constrain the models with the H I and He lines
- To better constrain the Prominence Corona Transition Region (PCTR) and the coronal environment
- To further study the dynamic of the PCTR (Doppler shift and NTV, dimming) in the low and high corona
- To compare these plasma properties for quiet, activated and erupted prominences.
The simultaneous use of SOHO/SUMER-CDS-UVCS, and Hinode instruments will be of great advantage for the purposes above mentioned.
SUMER will cover the full waveband on detector B (660 - 1500 Å, first order) in order to complement the Parenti at al. 2005a existing atlas and to study the H I Lyman series in line with Vial et al. 2007 work.
CDS observations will extend the atlas towards lower wavelengths, including the He I 584 Å and the He II 304 lines, proven to be very useful for diagnostic (Labrosse et al. 2007).
UVCS will provide informations of the prominence coronal environment through the Lya and O VI line profiles. They will be used to monitor the changes of the plasma properties in the erupted filament.
EIS will provide critical information on the line profiles at shorter wavelengths. In particular, the data will be used for studying the He continuum absorption and the He II 256 A line. EIS will also produce a context image of the observed prominence.
SOT will provide morphology and dynamic information of the cooler part of the prominence.
XRT will be used to study the prominence cavity and surrounding hot environment. |
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