Towards a Unified Understanding of Magnetic Braking - Mathias Schreiber

Описание: Mathias Schreiber (Universidad Técnica Federico Santa María, Brazil)

Abstract: During a solar eclipse the Sun is obscured, and its outer atmosphere (the corona) is revealed. The glow of the corona arises from scattering of light from electrons that are tied to the field lines of the Sun’s magnetic field. Observations of the solar corona during solar eclipse therefore illustrate an important astrophysical process: The magnetically guided winds of charged particles, extending out to interplanetary space, carry away angular momentum in a mechanism known as magnetic wind braking. Magnetic braking controls the rotational evolution and therefore magnetic activity of stars as they age, which is critical for habitability of exo-planetary systems as stellar magnetic activity can be harmful (and possibly sometimes helpful) to life. Knowing the rotational evolution of stars may further allow to measure precise stellar ages through gyrochronology which is fundamental for understanding the formation of our Galaxy. Furthermore, in close binary evolution theory, magnetic braking is crucial for constraining supernovae Type Ia progenitor channels. Notwithstanding its general importance for stellar astrophysics, our current understanding of magnetic braking is rather limited. The physics behind magnetic braking is rooted in stellar dynamos, mass loss, and the dependence of these phenomena on stellar mass, radius, and rotation period. Because these complex processes are far from fully understood, research on magnetic braking relies heavily on empirical approaches but current prescriptions for angular momentum loss through magnetic braking vary significantly and often lack a solid physical foundation. I will present recent attempts towards a unified understanding of magnetic with a focus on the evolution of close white dwarf binary stars.