Coronal emission lines as thermometers

TL;DR

This paper discusses the limitations of using coronal emission lines to measure electron temperatures, highlighting how systematic errors and data noise restrict the accuracy of temperature diagnostics despite increasing the number of lines.

Contribution

It reveals fundamental limits in temperature diagnostics from coronal emission lines due to atomic data uncertainties and noise, challenging assumptions about improving measurements by adding more lines.

Findings

Systematic errors limit temperature measurement accuracy.

Adding more emission lines does not necessarily improve discrimination.

Atomic data uncertainties fundamentally restrict diagnostic capabilities.

Abstract

Coronal emission line intensities are commonly used to measure electron temperatures using emission measure and/or line ratio methods. In the presence of systematic errors in atomic excitation calculations and data noise, the information on underlying temperature distributions is fundamentally limited. Increasing the number of emission lines used does not necessarily improve the ability to discriminate between different kinds of temperature distributions.