Differential rotation of the chromosphere in the He I absorption line

TL;DR

This study reveals that the solar chromosphere in the He I absorption line exhibits faster differential rotation than the photosphere, influenced by magnetic fields and small-scale magnetic elements, providing insights into solar dynamics.

Contribution

It presents new observational evidence of differential rotation in the chromosphere and explores magnetic field effects, advancing understanding of solar atmospheric dynamics.

Findings

Chromosphere rotates faster than the photosphere.

Magnetic fields strengthen chromospheric differential rotation.

Strong magnetic fields repress differential rotation at the photosphere.

Abstract

Differential rotation is the basis of the solar dynamo theory. Synoptic maps of He I intensity from Carrington rotations 2032 to 2135 are utilized to investigate the differential rotation of the solar chromosphere in the He I absorption line. The chromosphere is surprisingly found to rotate faster than the photosphere below it. The anomalous heating of the chromosphere and corona has been a big problem in modern astronomy. It is speculated that the small-scale magnetic elements with magnetic flux in the range of $(2.9 - 32.0)\times 10^{18}$ Mx which are anchored in the leptocline, heat the quiet chromosphere to present the anomalous temperature increase, causing it to rotate at the same rate as the leptocline. The differential of rotation rate in the chromosphere is found to be strengthened by strong magnetic fields, but in stark contrast, at the photosphere strong magnetic fields repress the differential of rotation rate. A plausible explanation is given for these findings.