Physics Dept. Seminar

September 26, Monday

Deep solar convection, properties of turbulent motions, large scale flows & convective conundrum

Prof. Gustavo Guerrero

Universidade Federal de Minas Gerais (UFMG), Brazil

(Solar Physics, Host: Gerrard)

Room: ECE 202

Time: 11:45 am - 12:45 pm with 11:30 am teatime

The magnetic activity observed at the solar atmosphere has its origin in the complex system of motions and currents happening in the solar convection zone. Large-scale motions, like the differential rotation and meridional circulation, and large-scale magnetic fields, originate from the turbulent convective motions occurring in the upper 30% of the solar interior. We are able to observe these motions at the solar photosphere in the form of granulation, with scales of several thousands of kilometers, and supergranulation, with scales of ∼30000 km. From theoretical considerations it is expected that larger, self-similar, motions exist at deeper layers. Their characteristics, however, remain evasive to observations. It is expected that spatial and temporal scales progressively increase with depth. Yet, helioseismic studies show that the energy of the large scales is orders of magnitude smaller than theoretical predictions. This challenges the theory of stellar structure and the models proposed to explain the origin of the differential rotation. This problem is known as the solar convective conundrum. In this talk, I'll present recent results of numerical simulations of deep solar convection where we study the effects of the grid resolution on the properties of the turbulent and large scale motions. The results suggest that obtaining the observed distribution of angular momentum may not be a mere issue of numerical resolution, and accounting for additional physics may be necessary to describe convection in the solar and stellar interiors. I'll discuss underway numerical and observational efforts to tackle the convective conundrum.