Taissa Danilovich

The secrets of intermediate-mass AGB stars unveiled through astrochemistry

The AGB phase is one of the later stages of stellar evolution for low and intermediate mass stars, during which stars expel a large portion of their stellar envelope. Observations of molecular lines allow us to study the circumstellar material around AGB stars, from which we can derive mass-loss rates and study the chemistry of dust formation. Previous studies of the molecules in AGB stellar winds found that several molecules have strong dependences on the mass-loss rate or the density of the wind, showing either different abundances or distributions with wind density. Other molecules are only present if there is a stellar companion affecting the wind chemistry with its UV light. To explore these phenomenon further, we examined the molecular emission around two of the highest mass-loss rate AGB stars that have been observed with ALMA. Both stars are also known to have intermediate initial masses (~4 to 8 solar masses). In addition to several expected molecules, we found a large number of emission lines coming from the salt molecules NaCl and KCl. I will discuss these findings and their implications for the chemistry and physics of the circumstellar environments of these stars.