Arief Ahmad (Uppsala University): Pulsations of dying giants – Investigating the self-excited pulsations of cool, luminous, and evolved stars in 3D models (Pre-defence seminar)

Thursday 30 Jan 2025, 14:00 → 15:00 Europe/Stockholm

101195Å

Title: Pulsations of dying giants – Investigating the self-excited pulsations of cool, luminous, and evolved stars in 3D models
Speaker: Arief Ahmad
Affiliation: Uppsala University
Time: Thursday 30 January 2025, 1400 to 1500
Location: 101195Å

Zoom: if requested 

Abstract:

Evolved stars on the asymptotic giant branch are cosmic factories, enriching the universe with essential elements like carbon through massive outflows of gas and dust. These outflows shape the stars’ evolution and contribute to the formation of new stars and planets. The connections between convection and pulsations, dust formation, and mass loss remain an area of active research.

On the stellar surface and in the surrounding dust clouds, observations reveal dynamic intricate structures. Such complex structures show up in our 3D radiation-hydrodynamics simulations of evolved cool giants, performed using the CO5BOLD code. These models demonstrate that pulsations, driven by interactions between convection and pulsations, influence the formation of shocks and dust in the stellar atmosphere. Multi-mode pulsations, including non-radial and overtone modes, emerge naturally, with their dominance varying based on stellar properties. These pulsations not only drive atmospheric dynamics but also create clumpy, anisotropic dust clouds that evolve over time, shaping the stars’ stellar winds. I will present key findings from our recent models, covering pulsation properties, advancements in our 3D simulations, and the attempts to characterise the massive dusty and clumpy outflows.