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Dwarf galaxies found in isolation in the Local Group (LG) are unlikely tohave interacted with the large LG spirals, and therefore environmental effectsshould not be the main drivers of their evolution. We aim to provide insightinto the internal mechanisms shaping LG dwarf galaxies by increasing ourknowledge of the internal properties of isolated systems. We focus on theevolved stellar component of the Aquarius dwarf, whose kinematic andmetallicity properties have only recently started to be explored. We haveobtained spectroscopic data in the the near-infrared CaII triplet lines regionwith FORS2 at the Very Large Telescope for 53 red giant branch (RGB) stars, toderive line-of-sight velocities and [Fe/H] of the individual RGB stars. We havederived a systemic velocity of $-142.2^{+1.8}_{-1.8}$ km s$^{-1}$, in agreementwith previous measurements from both the HI gas and stars. The internalkinematics of Aquarius appears to be best modelled by a combination of randommotions (l.o.s. velocity dispersion of $10.3^{+1.6}_{-1.3}$ km s$^{-1}$) andlinear rotation (with a gradient $-5.0^{+1.6}_{-1.9}$ km s$^{-1}$arcmin$^{-1}$) along a P.A.=$139_{-27}^{+17}$ deg, consistent with the opticalprojected major axis. This rotation signal is significantly misaligned or evencounter-rotating to that derived from the HI gas. We also find the tentativepresence of a mild negative metallicity gradient and indications that themetal-rich stars have a colder velocity dispersion than the metal-poor ones.This work represents a significant improvement with respect to previousmeasurements of the RGB stars of Aquarius, as it doubles the number of memberstars studied in the literature. We speculate that the misaligned rotationbetween the HI gas and evolved stellar component might have been the result ofrecent accretion of HI gas or re-accretion after gas-loss due to internalstellar feedback.

Kinematic and metallicity properties od the Aquarius dwarf galaxy from FORS2 MXU spectroscopy