Helicity at Photospheric and Chromospheric Heights

TL;DR

This study investigates the relationship of magnetic helicity between photospheric and chromospheric heights in the solar atmosphere using multi-height observations, aiming to understand the magnetic twist's behavior across different layers.

Contribution

It provides a detailed analysis of the correspondence of magnetic helicity at different atmospheric heights using simultaneous observations, which is a novel approach.

Findings

Helicity signs are consistent between photospheric and chromospheric features.

Chromospheric features show hemispheric dominance similar to photospheric helicity.

The study establishes a method for correlating helicity across atmospheric layers.

Abstract

In the solar atmosphere the twist parameter $\alpha$ has the same sign as magnetic helicity. It has been observed using photospheric vector magnetograms that negative/positive helicity is dominant in the northern/southern hemisphere of the Sun. Chromospheric features show dextral/sinistral dominance in the northern/southern hemisphere and sigmoids observed in X-rays also have a dominant sense of reverse-S/forward-S in the northern/southern hemisphere. It is of interest whether individual features have one-to-one correspondence in terms of helicity at different atmospheric heights. We use UBF \Halpha images from the Dunn Solar Telescope (DST) and other \Halpha data from Udaipur Solar Observatory and Big Bear Solar Observatory. Near-simultaneous vector magnetograms from the DST are used to establish one-to-one correspondence of helicity at photospheric and chromospheric heights. We plan to extend this investigation with more data including coronal intensities.