A detailed view on the circumstellar environment of the M-type AGB star EP Aquarii I. High-resolution ALMA and SPHERE observations

摘要: Cool evolved stars are known to be significant contributors the enrichment of interstellar medium through their dense and dusty stellar winds. High resolution observations these outflows have shown them possess high degrees morphological complexity. We observed asymptotic giant branch (AGB) star EP Aquarii with ALMA in band 6 VLT/SPHERE/ZIMPOL four filters visible. Both instruments had an angular 0.025''. These follow-up lower-resolution 2016 analysis Aquarii, which revealed that its wind possesses a nearly face-on, spiral-harbouring equatorial density enhancement, pole-on bi-conical outflow. At base spiral, SiO emission distinct void approximately 0.4'' west continuum brightness peak, was proposed linked presence companion. The new data better resolve inner reveal morphology as CO is consistent hydrodynamical companion-induced perturbations. Assuming photodissociation by UV-field companion responsible for SiO, we deduced spectral properties tentative from size hole. conclude most probable candidate white dwarf mass between 0.65 0.8 Msol , though solar-like could not definitively excluded. radial shows periodic, low-amplitude tentatively propose they consequence interaction AGB another much closer low-mass polarised SPHERE/ZIMPOL show circular signal surrounding radius 0.1''...