Energy levels, radiative rates, and electron impact excitation rates for transitions in O VII^*

Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland, UK e-mail: K.Aggarwal@qub.ac.uk

Received: 7 July 2008
Accepted: 7 August 2008

Abstract

Aims. In this paper we report calculations for energy levels, radiative rates, and electron impact excitation rates for transitions in O vii.

Methods. The grasp (general-purpose relativistic atomic structure package) is adopted for calculating energy levels and radiative rates. For determining the collision strengths and subsequently the excitation rates, the Dirac atomic R-matrix code (darc) and the flexible atomic code (fac) are used.

Results. Oscillator strengths, radiative rates, and line strengths are reported for all E1, E2, M1, and M2 transitions among the lowest 49 levels of O vii. Collision strengths have been averaged over a Maxwellian velocity distribution, and the resulting effective collision strengths are reported over a wide temperature range below 210⁶ K. Additionally, lifetimes are also listed for all levels.