Astrophysical Plasmas from the Sun to Black Holes

Everybody knows that matter on Earth can be commonly found in three states: solid, liquid, and gas. But if we consider the Universe in which we live, 99% of all matter exists in a fourth state, called "plasma": a gas so hot and dilute that electrons are free to escape the electric pull of atomic nuclei. All the stars in the Universe are made of plasma, which also fills the interstellar and intergalactic space; plasmas are also found around black holes and neutron stars; and gigantic jets of plasma moving nearly at the speed of light protrude from the center of many galaxies and extend for hundreds of thousands of light years. Studying astrophysical plasmas is then of prime importance to understand many fundamental processes occurring everywhere in our Universe. And yet, the study of plasmas is often very difficult: the equations that govern the plasma dynamics are extremely complicated, and usually can only be solved with the help of supercomputers carrying out calculations on thousands of CPUs. In this lecture, we will review the basic theory of plasmas by linking to phenomena that we commonly observe in many astrophysical environments, from our own Sun to the surroundings of supermassive black holes. We will learn about the governing equations of plasma dynamics and about how they are solved with computer calculations. We will then move onto more detailed topics, including the dynamics of plasmas in the Sun's atmosphere, the solar wind and the Earth's magnetosphere, astrophysical jets, and the surroundings of black holes and neutron stars.