Paper XLVI

Electron excitation of 3s3p$^6$ and 3s$^2$3p$^4$3d fine-structure transitions in Fe X

J.C. Pelan and K.A. Berrington

Astronomy & Astrophysics Supplement Series, 2000, in press

Electron excitation collision strengths for fine-structure collisions 3s$^2$3p$^5$ - 3s3p$^6$, 3s$^2$3p$^5$ - 3s$^2$3p$^4$3d and 3s3p$^6$ - 3s$^2$3p$^4$3d in Fe X, are calculated using a 180-level Breit-Pauli R-matrix calculation containing the above levels together with those from 3s3p$^5$3d and 3s$^2$3p$^3$3d$^2$ configurations. The collision strength is averaged over a Maxwellian velocity distribution to obtain the effective fine-structure collision strengths as a function of electron temperature form $\log T$(K) = 5.4 - 7.0. We show that the effective collision strength is considerably enhanced due to low-energy resonances.