The molecular and dusty composition of Betelgeuse s inner circumstellar environment

Context. The study of the atmosphere of red supergiant stars in general and of Betelgeuse ($\ alpha $ Orionis) in particular is of prime importance to understand dust formation and how mass is lost to the interstellar medium in evolved massive stars. Aims. A molecular shell, the MOLsphere (Tsuji 2000a, ApJ, 538, 801), in the atmosphere of Betelgeuse has been proposed to account for the near-and mid-infrared spectroscopic observations of Betelgeuse. The goal is to further test this hypothesis and to identify some ...