# Discovery of stars surrounded by iron dust in the LMC

## TL;DR

This study identifies a new class of oxygen-rich AGB stars in the LMC with iron dust-dominated envelopes, challenging previous silicate-centric dust models and providing insights for JWST data interpretation.

## Contribution

It reveals a novel type of AGB stars with iron dust dominance, linked to low metallicity and recent star formation, expanding understanding of stellar dust composition.

## Key findings

- Stars are surrounded by iron dust instead of silicates.
- These stars are likely from a metal-poor, recent star formation episode.
- Silicate formation is suppressed due to nucleosynthesis effects.

## Abstract

We consider a small sample of oxygen-rich, asymptotic giant branch stars in the Large Magellanic Cloud, observed by the Spitzer Space Telescope, exhibiting a peculiar spectral energy distribution, which can be hardly explained by the common assumption that dust around AGB stars is primarily composed of silicate grains. We suggest that this uncommon class of objects are the progeny of a metal-poor generation of stars, with metallicity $Z \sim 1-2\times 10^{-3}$, formed $\sim 100$ Myr ago. The main dust component in the circumstellar envelope is solid iron. In these stars the poor formation of silicates is set by the strong nucleosynthesis experienced at the base of the envelope, which provokes a scarcity of magnesium atoms and water molecules, required to the silicate formation. The importance of the present results to interpret the data from the incoming James Webb Space Telescope is also discussed.