Luminous Blue Variable stars as dust factories at sub-solar metallicities

Luminous Blue Variable stars are blue supergiants that undergo instabilities and experience outbursts with high mass-loss rates. An extreme example is eta Car, that in the XIX century ejected more than 40 solar masses at rates higher than 0.1 Msun/yr. Several Galactic LBVs exhibit extended circumstellar nebulae, often with large masses of dust (~0.01 Msun). How this dust is formed is not well understood, but the physical conditions in their ejecta during the giant eruptions seem favourable for the formation and growth of dust. Thus LBVs are candidate producers of dust in the early Universe, where massive stars were more numerous than at present.