Differential coronal rotation using radio images at 17 GHz

TL;DR

This study analyzes solar corona rotation at different latitudes using radio images from NoRH at 17 GHz, revealing that the corona exhibits less differential rotation than the photosphere and chromosphere.

Contribution

It introduces a time-series analysis method to measure coronal rotation at various latitudes using radio images, extending previous studies with new observational data.

Findings

Coronal rotation is less differential than the photosphere.

Rotation rate gradient decreases with altitude.

Radio features trace coronal rotation effectively.

Abstract

In the present work, we perform time-series analysis on the latitude bins of the solar full disk (SFD) images of Nobeyama Radioheliograph (NoRH) at 17 GHz. The flux modulation method traces the passage of radio features over the solar disc and the autocorrelation analysis of the time-series data of SFD images (one per day) for the period 1999-2001 gives the rotation period as a function of latitude extending from 60 degree S to 60 degree N. The results show that the solar corona rotates less differentially than the photosphere and chromosphere, i.e., it has smaller gradient in the rotation rate.