Radiation Transfer and Stellar Atmospheres

This course covers the essentials needed for a good understanding of the physics of atmospheres and stellar winds. The key elements of radiation transfer theory are covered, both in local thermodynamic equilibrium (LTE) and off-LTE, as well as the description of gas (equation of state) and its interaction with the radiation field (opacities). Modern models and simulations are presented with their application to the determination of stellar parameters, in particular chemical composition, via spectroscopy. The different types of stellar winds (pressure, radiative, hybrid) are described using theories compared with observations.

Ensure a solid foundation in radiative transfer to address most problems in astrophysics.

Acquire the fundamentals of stellar atmosphere physics, enabling you to tackle specialized publications in the field.

Know the essential theories of stellar winds and related mechanisms.

Knowing how to apply this knowledge to perform calculations, estimate orders of magnitude, or test a theory.

Be aware of the existence of iconic numerical codes for simulating atmospheres and their field of application.

Recommended prerequisites:

Fundamentals of astrophysics, quantum mechanics, atomic physics, statistical physics

Continuous assessment

Advanced radiative transfer: ETL, off-ETL, line formation, atomic processes, radiative equilibrium, gray atmosphere

Stellar atmospheres: equations and physical ingredients, structure, hydrostatic atmospheres, convection, 3D radiative hydrodynamic simulations, diagnostics

Stellar spectroscopy: two-level atom, line broadening, determination of the chemical composition of atmospheres

Stellar winds: solar wind, radiation winds from hot stars, hybrid winds from red giants