ALMA spectroscopy toward a recent ejecta in eta Carina

Eta Carina is by far the most intriguing luminous blue variable (LBV) star in our Galaxy. Despite periodic light variations associated to a binary orbit, the system underwent several, impressive brightening in the past two centuries. We analyze ALMA band 7 observations of continuum and molecular data (CO, HCO+, HCN, H13CN), at angular resolutions below 200 mas. We have discovered extended continuum circumstellar emission at distances under 1000au, and HCO+ associated to this structure. CO, HCN and H13CN are only present at larger distances but not so close to the star. We measure an extremely low 12C/13C (around 1), which may not be due to opacity effects, but to real isotopic abundance associated to star nucleosynthesis. Also puzzling is the non-detection of CO where HCO+ is abundant. HCN are H13CN are found in hot bullets, probably ejected from eta Carina. All these findings make this source of great interest, because the understanding of the chemistry of the circumstellar molecular gas may provide keys about the physical processes which drive the star evolution.