Rotation of the low temperature regions (LTR) at 8 mm

Background: In this work, we investigate rotation of the low temperature region (LTR) of the Sun at the radio wavelength of 8 mm. The temperature of these areas is less than the quiet Sun temperature (8200 ± 500 K at 8 mm). We found 100 representative LTR sources. The analyzed data is obtained from solar radio maps (Metsähovi Radio Observatory, Aalto University, Finland). The data is recorded between 1989 and 2014 both during the solar maximum and minimum. Our results show that the rotation rates of LTRs match the best with the coronal holes rotation. Our results also show that the rotation is quite rigid