ar X iv : a st ro - p h / 02 04 04 9 v 1 3 A pr 2 00 2 1 HELIUM - LIKE TRIPLET DIAGNOSTICS
نویسندگان
چکیده
The 1s 2 –1s2l lines are the most intense He-like ions lines. They are used as spectroscopic diagnostics for solar active regions as well as for different laboratory plasmas. Nowadays, it exits very high spectral resolution instruments and, for intense X-ray sources, one can do spectro-scopic diagnostics from line ratios. With XMM (RGS) and Chandra (LETGS, HETGS) spectral resolutions and for several atomic elements, it is particularly possible to separate a 3 blended line set, the so-called He-like triplet: Resonance (r), Intercombination (i) and Forbidden (f), which are dominated respectively by lines issued from the following levels : 1s2p 1 P 1 , 1s2p 3 P 1,2 , and 1s2s 3 S 1. We shall show that the measurement of two different ratios between these 3 lines (R = f/i and G = (f + i)/r) give quantitative informations on the nature of the emitting plasma (photo-ionized or collisional) and on its electronic density and temperature. A more refined analysis must also include satellite line contributions.
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تاریخ انتشار 2002