MATISSE unveils a dusty disc in the interior of EP Aquarii. First evidence of a misaligned hierarchical triple system with a central AGB star?

Aims. We have mapped the dust and molecular gas emission distributions in the vicinity (a few stellar radii) of the asymptotic giant branch (AGB) star EP,Aquarii, with a previously reported stellar companion at about 50,au, to search for binary-induced asymmetries. Methods. We present an analysis of new high-angular-resolution (4,mas) images obtained with MATISSE (in the wavelength range about 3--8,) as well as archival high-angular-resolution (20,mas) ALMA 12 CO,(c J =2-1) line and continuum emission observations (about 230,GHz), to study the circumstellar morphology and kinematics of the molecular gas on these spatial scales. Results. The MATISSE images display a bright central source and two slightly extended emission features ("blobs") located on opposite sides of the AGB star (at radial distances of about 4--10,au). These structures are consistent with previous mid-infrared interferometric observations, suggesting stability over decades. The central source is elongated along the direction defined by the blobs, in both the MATISSE and ALMA continuum images. The ALMA 12 CO,(J =2-1) maps display an asymmetric inner wind with a velocity gradient. Conclusions. The observations are consistent with an edge-on dusty equatorial overdensity (disc-like), hinting the presence of a close (4,au) companion. The inferred symmetry axis is almost perpendicular to the CO velocity gradient and the orbital plane proposed for the distant (about 50,au) companion. EP,Aqr may represent the first misaligned hierarchical triple system with a central AGB star.