Abstract

Contributed Talk - Splinter DustEvol

Thursday, 12 September 2024, 16:50   (S12)

The role of AGB stars in the origin of dust in the interstellar medium

Maercker, Khouri, Mecina, De Beck
Chalmers University of Technology, University of Vienna

Asymptotic giant branch (AGB) stars contribute to the chemical evolution of galaxies through the dust grains they release into the interstellar medium (ISM). The detection of pre-solar grains in meteorites shows that at least some of the dust from AGB stars survives the transition into the ISM. It is likely that these grains act as seeds for further dust-growth in the ISM leading to the final observed interstellar dust, in addition to dust from supernovae. I will present a detailed analysis of the dust emission observed with Herschel/PACS at 70 and 160 micron towards wind-ISM interaction regions around a sample of 22 carbon and oxygen-rich AGB stars. My results show that there is a tendency for the grains in the wind-ISM interaction regions to be relatively large (approx. 2 micron), while several uncertainties that affect commonly made basic assumptions on interstellar dust (e.g., composition and morphology) become obvious. At the same time, the dust observed in the ISM is distinctly different from the dust observed in the circumstellar envelopes around low-mass evolved stars. The physical conditions in the regions where the stellar wind interacts with the ISM may lead to significant reprocessing of the grains, strongly affecting properties like the size, structure, geometry, and composition of the grains. Our lack of understanding affects our knowledge of the contribution of dust to the ISM from AGB stars in comparison to supernovae, and hence the origin of the cycle of dust in the ISM. The same uncertainties may also affect the interpretation of dust around massive evolved stars, further complicating the picture. Our results show a path forward in investigating the origin of interstellar dust, the cycle of dust in galaxies, and the effect on the chemical evolution of the ISM.