Table 4: Best-fit parameter values for the different single non-equilibrium models using the MOS and pn data all at once. The first model refers to the NEI model with all elements fixed to solar abundances. The second model refers to the NEI model with all the elemental abundances (C, N, O, Ne, Mg, Si, S, Ca, Fe, Ni) freely fitted excepted H and He which were frozen to solar abundances. The second model leads to abundances of C, N, O, Ne, Ca near zero. The errors are in the range $\Delta \chi ^2 < 2.7$ (90% confidence level) on one parameter. Quantities in square brackets are held fixed at the given value.
Parameter Solar abundances Free abundances
k T (keV) 2.8 (2.4-2.8) 3.0 (2.8-3.2)
$\tau$ (109 s cm-3) 5.0 (4.9-5.3) 8.6 (7.9-9.4)
Si (Ab$_\odot$) [1] 1.6 (1.3-1.8)
S (Ab$_\odot$) [1] 0.4 (0.1-0.7)
Fe (Ab$_\odot$) [1] 0.14 (0.12-0.16)
Norm $6.0 \times 10^{-4}$ (5.6-6.5) $ 5.0 \times 10^{-4}$ (4.6-5.5)
$N_{{\rm H}}$ (1022 cm-2) 0.86 (0.84-0.87) 0.30 (0.27-0.33)
$\chi^2$ 1287/607 d.o.f. 693/596 d.o.f.


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