Author:

Abstract:

Asymptotic giant branch stars, stars similar to the Sun but in a more evolved stage, harbour a strong stellar wind, giving rise to a vast circumstellar envelope. This envelope is notably rich in chemistry, as a variety of molecules and dust species has been detected. Furthermore, within their interiors, these stars synthesise heavy elements that are dredged up to the surface thanks to their turbulent layers. As such, these stars fuel the interstellar medium with dust and gas enriched by nucleosynthesis, providing essential building blocks for later generations of stars and planets. Recently, observations revealed that the circumstellar envelopes of these stars exhibit complex morphologies, challenging the long-held assumption of spherical symmetry. It is believed that fainter companion stars or planets, concealed within the dusty envelope, are responsible for the observed asymmetries through gravitational interaction. Numerical simulations confirm that gravitational interactions can indeed shape the envelope. However, the exact nature of these interactions is not well understood, nor is the impact on the chemical compositio of the envelope. Moreover, hitherto determined prescriptions for mass-loss rates and other wind parameters, such as wind velocity, may be inaccurate, as they are based on the assumption of spherical symmetry. Hence, to correctly predict the chemical composition of the envelopes, as well as mass-loss rates, wind parameters, and yields, it is necessary to model the circumstellar envelope in a 3D framework including hydrodynamics, chemistry, and radiative transfer.