The kinematical behavior of ORLs and CELs in PNe with [WC] central star

TL;DR

This study investigates the differing kinematic behaviors of collisionally excited lines and recombination lines in planetary nebulae with [WC] stars, revealing that they originate from distinct zones within the nebulae, which may explain the abundance discrepancy.

Contribution

It provides new evidence that ORLs and CELs originate from different regions in PNe with [WC] stars, contributing to understanding the abundance discrepancy problem.

Findings

ORLs and CELs have incompatible kinematics in PNe.

Expansion velocities differ for the same ion between ORLs and CELs.

ORLs are produced closer to the central star than CELs.

Abstract

In Planetary Nebulae (PNe) and HII regions ionic abundances can be derived by using collisionally excited lines (CELs) or recombination lines (ORLs). Such abundances do not coincide for the same ion and usually abundances from ORLs are larger than those from CELs by factors of 2 or larger. The origin of the discrepancy, known as the Abundance Discrepancy Factor is an open problem in astrophysics of gaseous nebulae. It has been attributed to temperature fluctuations in the plasma, tiny metal-rich inclusions embedded in the H-rich plasma, gas inhomogeneities or other processes. In this work we analyze the kinematical behavior of CELs and ORLs in two PNe ionized by [WC] stars, finding that kinematics of ORLS is incompatible with the kinematics of CELs. In particular the expansion velocities from CELs and ORLs for the same ion are different, indicating that ORLs seem to be produced in zones nearer the central star than CELs. This is in agreement with results found by other authors for individual PNe.