Stellar winds of cool giant stars as sites of cosmic dust formation
The Swedish Research Council reached a decision on November 4, 2021 on project grants and starting grants within Natural and Engineering Sciences. The Department of Physics and Astronomy is granted 44 160 000 SEK for the period 2021-2025 for in total nine project grants and three starting grants. The projects will begin during 2021.
Project title: Stellar winds of cool giant stars as sites of cosmic dust formation
Main applicant: Sara Bladh, Division of Astronomy and Space Physics
Grant amount: 4 000 000 SEK for the period 2022-2025
Cosmic dust permeates the universe and plays a crucial role in the evolution of galaxies by cooling the molecular clouds in which new stars and planets are born. In the early stages of galaxy evolution cool giant stars and supernovae are considered the main sources of cosmic dust, but the relative contribution from each production site is not well understood. For cool giant stars the main uncertainty lies in how the winds that transport dust into the interstellar medium are affected by the metal-poor environments in the early Universe. Since metal-poor stars have to manufacture the constituent elements of dust themselves, it is unclear if dust-driven winds can be produced.
The proposed project will drastically advance our understanding of how much metal-poor giant stars contribute to the dust production by using radiation-hydrodynamic wind models to investigate the conditions required to accelerate the winds that seed their host galaxy with dust. The overall chemical composition of these wind models will be scaled by metallicity to mimic the condition in early galaxy evolution, while the abundance of key elements for dust formation will be allowed to vary to account for dredge-up of fused material from the ongoing nucleosynthesis in the stellar interior. This is a first step towards predictive wind models for metal-poor stars, from which we can derive mass-loss rates and dust yields from cool giant stars in the early stages of galaxy formation.