  Evolved low- to intermediate-mass stars are known to shed their gaseous
envelope into a large, dusty, molecule-rich circumstellar nebula which
typically develops a high degree of structural complexity. Most of the
large-scale, spatially correlated structures in the nebula are thought to
originate from the interaction of the stellar wind with a companion. As part of
the Atomium large programme, we observed the M-type asymptotic giant branch
(AGB) star R Hydrae with ALMA. The morphology of the inner wind of R Hya, which
has a known companion at ~3500 au, was determined from maps of CO and SiO
obtained at high angular resolution. A map of the CO emission reveals a
multi-layered structure consisting of a large elliptical feature at an angular
scale of ~10'' that is oriented along the north-south axis. The wind morphology
within the elliptical feature is dominated by two hollow bubbles. The bubbles
are on opposite sides of the AGB star and lie along an axis with a position
angle of ~115 deg. Both bubbles are offset from the central star, and their
appearance in the SiO channel maps indicates that they might be shock waves
travelling through the AGB wind. An estimate of the dynamical age of the
bubbles yields an age of the order of 100 yr, which is in agreement with the
previously proposed elapsed time since the star last underwent a thermal pulse.
When the CO and SiO emission is examined on subarcsecond angular scales, there
is evidence for an inclined, differentially rotating equatorial density
enhancement, strongly suggesting the presence of a second nearby companion. The
position angle of the major axis of this disc is ~70 deg in the plane of the
sky. We tentatively estimate that a lower limit on the mass of the nearby
companion is ~0.65 Msol on the basis of the highest measured speeds in the disc
and the location of its inner rim at ~6 au from the AGB star.
