The inner dust shell of Betelgeuse seen with polarimetry

Abstract

AbstractThe origin of red supergiant mass loss still remains to be understood. Characterizing the formation zone and the dust distribution within a few stellar radii above the surface is key to understanding the mass loss phenomenon. With its angular diameter of about 42 mas in the optical, Betelgeuse makes an ideal target to resolve the inner structures that represent potential signatures of dust formation. Past polarimetric observations reveal a dust environment in the first stellar radii. Depending on their characteristics and composition, dust grains could interact with the stellar radiation, trigger mass loss by momentum transfer from photons to dust to gas. Using spatially-resolved polarimetric observations of Betelgeuse, we detect a quasi-symmetric inner dust shell centered at ∼0.5 stellar radii above the photosphere and attempt at constraining its dust population.