The He I and He II chromospheric shells and the Transition Region

TL;DR

This study uses eclipse observations and advanced imaging to explore the structure of helium shells and the transition region in the solar atmosphere, revealing new insights into their depths and dynamics.

Contribution

It provides the first evidence of a second He II shell and details the transition region at very low altitudes using high-resolution imaging.

Findings

Detection of a second He II shell.

Transition region observed at very low altitude.

Analysis of spicule foot dynamics.

Abstract

Total eclipse observations were performed in 2008 and 2009 to study the He I and He II shells near the 1 Mm heights above the solar limb. They suggest that the corona penetrates deep into the chromosphere following magnetic chanels. Thanks to the use of a fast CCD camera, the observation of a second ionized helium shell is evidenced for the first time. The transition region is then seen at very low altitude where spicules are emerging. Spicule feet are also discussed, using the best resolution SOT/Hinode HCaII images processed with the non linear operator Madmax to look at details of this ubiquitous part of the solar atmosphere.