The objective of this proposal is to build a prominence diagnostic focused on some HeI-HeII in conjonction with H lines. Although prominences (as other solar features) are daily observed in He II (30.4nm) with EIT/SoHO, not many studies have been devoted to the emission of He (I and II) in conjonction with H lines in prominences, in contrast with the modelling performed by Labrosse et al. which now includes velocity effects (Labrosse et al. 2007, 2008). There are various reasons for that, including the fact that the various lines are located in rather distant wavelength ranges, which impedes simultaneous observations. This drawback can (partially) be solved if one uses a set of He II lines which are located in the blue wings of the Lyman series (see the Parenti at al. 2005 Atlas). As discussed by Ebadi et al. (2008), these lines are actually the even Balmer lines of He II and they have been measured up to L10.
The above-mentioned measurements are unfortunately characterized by : * a dispersion in time and objects and * a difficult (impossible ?) detection of the first even Balmer He II line (2p 2P3/2-4d 2D3/2) when the SUMER attenuator is used to record the Lalpha line.
The objective of this JOP/HOP is to record clean He I, II and H lines on the same feature within a time interval as short as possible.
A first version of the JOP/HOP consists in getting the first even Balmer line in a proper way (WITHOUT the Lalpha attenuator) along with the following line located in the Lbeta line wing in order to have a reference with respect to previous measurements (Ebadi et al. 2008).
Other H and He lines are of great interest. We recall here that the lower level of the Balmer lines is just the upper level 2P3/2 of the resonance He II 30.4 nm line.
We also recall that the ionization properties of prominences are essentially determined by H which requires the Lyman lines to be recorded and computed.
References : H. Ebadi, J.-C. Vial, A. Ajabshirizadeh, 2008, The HeII and DI lines in the Lyman series profiles of solar prominences, accepted in Solar Physics
Labrosse, N., Gouttebroze, P., and Vial, J.-C., 2007, Effect of motions in prominences on the helium resonance lines in the extreme ultraviolet, Astronomy and Astrophysics, 463, 1171
Labrosse, N., Vial, J.-C., Gouttebroze, P., 2008, Diagnostics of active and eruptive prominences through hydrogen and helium lines modelling, Ann. Geophys., 26, 2961
S. Parenti, J.-C. Vial, P. Lemaire, 2005, Prominence Atlas in the SUMER range 800 - 1250 A II. Line profile properties ans ions identifications, Astron. and Astrophys., 443, 685 |
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