February 23rd, 2018, 1:00 pm - 2:00 pm

October 5th, 1:00 pm - 2:00 pm

Spying on the heart of the solar dynamo

Sushant S. Mahajan, Georgia State University

Sunspots have been observed and recorded for over four centuries, yet their origin still remains a mystery. With the advent of Helioseismology, the differential rotation of the Sun has been measured throughout its convection zone with good enough accuracy to reveal modulation in it over time. This modulation in differential rotation called torsional oscillation has a period of 11 years and shows spatio-temporal correlation with the sunspot cycle leading to speculations that torsional oscillation is either a driver or a tracer of the sunspot cycle. Our analysis of the phase relationship between torsional oscillation and the sunspot cycle suggests that the shear in differential rotation of the Sun is maximum during solar minima and minimum during solar maxima which supports the classical solar dynamo theory. It also implies that the overall differential rotation drives the solar cycle while torsional oscillation acts as a tracer. Thus, tracking the regions of decreasing latitudinal shear gives us a way to map the regions of magnetic field amplification inside the Sun and answer a 408 years old question.