Discovery of stars surrounded by iron dust in the LMC

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.

Accepted for publication in ApJ Letter on 9 January 2019

References in corpus (7)

• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• The dust production rate of AGB stars in the Magellanic Clouds
• The Mass-Loss Return From Evolved Stars to the LMC: Empirical Relations for Excess Emission at 8 and 24 μm
• Luminosities and mass-loss rates of Local Group AGB stars and Red Supergiants
• An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). IV. Discovery of High-Redshift AGB Analogs
• On the alumina dust production in the winds of O-rich Asymptotic Giant Branch stars
• Dissecting the Spitzer color-magnitude diagrams of extreme LMC AGB stars

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• Mid-infrared evidence for iron-rich dust in the multi-ringed inner disk of HD 144432
• Circumstellar CO J = 3-2 detected around the evolving metal-poor ([Fe/H] ~ -1.15 dex) AGB star RU Vulpeculae
• Do evolved stars in the LMC show dual dust chemistry?
• OGLE-2002-BLG-360: a dusty anomaly among red nova remnants