The Density of Coronal Null Points from Hinode and MDI

TL;DR

This study compares methods to estimate the density of magnetic null points in the quiet Sun using Hinode and MDI magnetograms, finding consistent results around 0.003 null points per square Mm.

Contribution

It demonstrates the agreement between different computational methods and data sources for estimating null point density in the solar magnetic field.

Findings

All methods yield a null point density of approximately 0.003 null points per square Mm.

Results are consistent across Hinode and MDI magnetograms.

The estimated density aligns with previous measurements.

Abstract

Magnetic null points can be located numerically in a potential field extrapolation or their average density can be estimated from the Fourier spectrum of a magnetogram. We use both methods to compute the null point density from a quiet Sun magnetogram made with Hinode's NFI and from magnetograms from SOHO's MDI in both its high-resolution and low-resolution modes. All estimates of the super-chromospheric column density (z>1.5 Mm) agree with one another and with the previous measurements: 0.003 null points per square Mm of solar surface.