Recombination Lines of CII in the Spectra of Planetary Nebulae

TL;DR

This study investigates CII recombination lines in planetary nebulae spectra by generating theoretical data for CIII targets, comparing with experimental data, and analyzing observational lines to determine the nebula's temperature.

Contribution

It introduces new theoretical data for CIII targets using R-matrix and Autostructure codes and applies a novel emissivity calculation tool to analyze nebular spectra.

Findings

Good agreement between theoretical and experimental data.

Determined nebular temperature of approximately 10200-10500K.

Validated the use of the `Emissivity` code for spectral analysis.

Abstract

The current report presents the work to investigate the recombination lines of CII in the spectra of planetary nebulae. Two CIII targets were prepared and used to generate theoretical data required in the investigation of recombination lines that arise from collisions between electrons and ions in thin plasma found in planetary nebulae and other astrophysical objects. One of these targets contains 9 atomic terms while the other contains 26 terms. For each one of these targets, theoretical data concerning bound and autoionizing states were generated in the intermediate coupling approximation by R-matrix and Autostructure codes and compared to experimental data. The comparison revealed very good agreement. These theoretical data were then used to generate emissivity data and compare it to the carbon recombination lines found in the observational line list of Zhang et al [2005] on the planetary nebula NGC 7027. The main tool used in this analysis is the `Emissivity' code which is a program developed by the author [2010] in the course of this investigation to calculate the emissivity of transition lines from resonances and subsequent cascade decay. The results of the analysis from both targets using a least-squares optimization technique indicate a temperature of 10200-10500K of the line-emitting region.