Differential coronal rotation using radio images at 17 GHz

In the present work, we perform time-series analysis on the latitude bins of the solar full disc (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°S to 60°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.