FeII Lines in the Palomar Bright Quasar Survey

Abstract

Grandi (1981) and Netzer and Wills (1983) have shown that FeII lines are prominent in the spectra of quasars. Wills, Netzer and Wills (1985) have shown that FeII can be the single strongest contributor to the emission line spectrum. Because the FeII spectrum consists of thousands of lines there are many escape routes in the FeII spectrum for energy absorbed by the fairly abundant Fe⁺ ion. It is becoming increasingly clear that the resonance lines of FeII are optically thick (Wills, Netzer and Wills, 1985) This contributes to the excitation of high lying levels through fluorescence pumping from the lower lying levels. Quasar spectra, unlike the spectra of galactic stars such as ŋ Car, do not show forbidden lines in emission (Wampler and Oke, 1967; Wampler, 1985). Understanding the FeII excitation and radiative processes in quasars will lead to a better understanding of the energy balance in the broad line region and the abundance of metals in the nuclear engine.