Investigating the inner circumstellar envelopes of oxygen-rich evolved stars with ALMA observations of high- J SiO masers.

We highlight a few results from ALMA Band 6 observations of high-rotational transition number (J) SiO masers towards oxygen-rich AGB and red supergiant stars carried out as part of the ATOMIUM Large Programme in 2018–2020. A search for a relationship between mass-loss rates and flux-weighted mean angular distances of maser components was inconclusive, as linear regression models for the 28SiO v =1 J =5–4 and J =6–5 transitions were inconsistent. Supplementary APEX observations towards the ATOMIUM AGB stars also suggest variability at different stellar pulsation phases. [ABSTRACT FROM AUTHOR]