SHAO Astrophysics Colloquium

Title: The solar cycle: its variability and prediction

Speaker: Prof. Jie Jiang (Beihang University)

Time: 3 pm, July 4 (Thursday)

Location: Lecture hall, 3rd floor

Abstract:

Solar activity, e.g., sunspots, flares, coronal mass ejections and so on, shows a roughly 11-year cycle period, which is the so-called solar cycle with widely varying amplitudes. In our technological society, the effects of the solar cycle on human society are becoming more and more significant. Nowadays, it is regarded as nature's third most important cycle for our lives. In this talk, I will present our efforts to understand causes of variability in the solar cycle and to develop models to predict solar cycles.

Special Colloquium

Title: Energy Evolution and Particle Energization in Turbulent Astrophysical Plasmas

Hui Li (LANL)

Time: July 5, 2019 (Friday) 10am

Location: Lecture hall, third floor

Abstract: Plasma turbulence and magnetic reconnection are ubiquitous in astrophysical environments. Particle energization often arises in such environments, such as solar coronal heating, flares from accretion disk coronae and astrophysical jets. Recent theoretical and numerical studies have highlighted the role of dynamic current sheets, including their formation and associated reconnection processes, which in turn are postulated to strongly impact the turbulence dynamics as well as particle energization processes. Here, we present 3D MHD and kinetic simulations to study the interplay between turbulence and the pre-existing current sheets. These systems are large enough that turbulence can be fully developed. Whereas some turbulence properties are similar between these two cases, we highlight the differences in available free energy that can lead to different particle energization efficiency and processes. We will discuss the implications for solar and accretion disk corona and astrophysical jets.