Comparative analysis of solar minima with EUV tomography

DIEGO G. LLOVERAS; FEDERICO A. NUEVO; ALBERTO M. VÁSQUEZ; RICHARD A. FRAZIN

La Plata - Buenos Aires

Congreso; 58ª Reunión Anual de la Asociación Argentina De Astronomía; 2015

Due to the dynamo mechanism of the Sun, the magnetic activity of its atmosphere presents a periodic cycle about 11 years long. The last three solar cycles have shown a systematic decrease of activity, with the last minimum (2008/2009) being considerably more quiet than the previous one (1996), as well as magnetically weaker. We present a comparative analysis of three-dimensional (3D) thermodynamical structure of the lower corona for last two minimima, based on differential emission measure tomography (DEMT). The study is combined with potential extrapolations of the coronal magnetic field. To study the minima of 1996 and 2009 we use data taken by the instruments EIT/SOHO and EUVI/STEREO, respectively. The aim of the work is to establish if there were systematic thermodynamical differences in the lower corona during the two minima.