Sensitivity coefficients to $\alpha$-variation for astrophysically relevant transitions in Ni II

Abstract

We calculated the dependence of the transition frequencies on the fine-structure constant $\alpha$ ($q$-factors) for Ni~II. Nickel is one of the few elements with high sensitivity to $\alpha$-variation, whose lines are observed at high redshifts. This makes it a sensitive probe for $\alpha$-variation on the cosmological timescale. The electronic structure of Ni II ion was treated within the configuration interaction (CI) method using Dirac-Coulomb Hamiltonian.