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Abstract:
Pristine stardust grains from the interstellar gas and dust cloud from which our Solar System formed some 4.57 billion years ago are present in small quantities in primitive Solar System materials, such as certain types of meteorite, interplanetary dust particles and cometary matter. As these grains are older than our Solar System, they are known as presolar grains. They can be recognized because they carry large isotopic abundance anomalies that are the result of nucleosynthetic processes in their parent stars, namely, asymptotic giant branch stars, supergiants, supernovae and novae. From astronomical observations and dust-evolution models, it is still not clear to what extent various stellar sources, especially supernovae, contributed dust to the interstellar medium. Since the discovery of presolar grains more than 30 years ago, supernova grains have been considered to be only a minor subpopulation of presolar grains, with relative contributions of ∼10% for silicates, the most abundant type of presolar stardust grains. Recently conducted studies of presolar grains with improved analysis techniques have changed this view considerably, and suggest that supernovae and their progenitors contributed substantially to the dust inventory of the solar nebula, namely, >30% for silicates and >25% in total if other stardust minerals are considered. Here we review the recent findings from studies of presolar grains and discuss implications for future presolar grain studies, interstellar dust models and the interpretation of astronomical observations of dust in supernova ejecta.
