Decoding the message from meteoritic stardust silicon carbide grains

TL;DR

This study analyzes silicon carbide stardust grains from meteorites, revealing how their isotopic compositions reflect the chemical evolution and dust formation processes in ancient stars and the galaxy.

Contribution

It demonstrates that the isotopic distribution of SiC grains encodes information about stellar age-metallicity spread and dust formation efficiency, linking chemistry and galaxy evolution.

Findings

Isotopic compositions indicate a spread in parent star ages and metallicities.

Dust formation efficiency increases with metallicity following a power-law.

Results inform models of galactic chemical evolution and stellar dust condensation.

Abstract

Micron-sized stardust grains that originated in ancient stars are recovered from meteorites and analysed using high-resolution mass spectrometry. The most widely studied type of stardust is silicon carbide (SiC). Thousands of these grains have been analysed with high precision for their Si isotopic composition. Here we show that the distribution of the Si isotopic composition of the vast majority of stardust SiC grains carry the imprints of a spread in the age-metallicity distribution of their parent stars and of a power-law increase of the relative formation efficiency of SiC dust with the metallicity. This result offers a solution for the long-standing problem of silicon in stardust SiC grains, confirms the necessity of coupling chemistry and dynamics in simulations of the chemical evolution of our Galaxy, and constrains the modelling of dust condensation in stellar winds as function of the metallicity.