# Recombination coefficients for O II lines in nebular conditions

## TL;DR

This paper provides detailed recombination coefficients for O II lines in nebular conditions, accounting for electron density and temperature effects, useful for interpreting nebular spectra.

## Contribution

It introduces comprehensive recombination data for O II lines, including low-temperature dielectronic recombination, with an interactive data server for practical use.

## Key findings

- Recombination coefficients for 8889 lines are calculated.
- Data covers a wide range of electron densities and temperatures.
- Application examples demonstrate usefulness for nebular observations.

## Abstract

We present the results of a calculation of recombination coefficients for O^{2+} + e^- using an intermediate coupling treatment that fully accounts for the dependence of the distribution of population among the ground levels of O^{2+} on electron density and temperature. The calculation is extended down to low electron temperatures where dielectronic recombination arising from Rydberg states converging on the O^{2+} ground levels is an important process. The data, which consist of emission coefficients for 8889 recombination lines and recombination coefficients for the ground and metastable states of O^+ are in Cases A, B and C, and are organised as a function of the electron temperature and number density, as well as wavelength. An interactive fortran 77 data server is also provided as an accessory for mining the line emission coefficients and obtaining Lagrange interpolated values for any choice of the two variables between the explicitly provided values for any set of wavelengths. Some illustrations of the application of the new data to nebular observations are also provided.