The MAGIC project. III. Radial and azimuthal Galactic abundance
  gradients using classical Cepheids
  Radial abundance gradients provide sound constraints for chemo-dynamical
models of galaxies. Azimuthal variations of abundance ratios are solid
diagnostics to understand their chemical enrichment. In this paper we
investigate azimuthal variations of abundances in the Milky Way using Cepheids.
We provide the detailed chemical composition (25 elements) of 105 Classical
Cepheids from high-resolution SALT spectra observed by the MAGIC project.
Negative abundance gradients, with abundances decreasing from the inner to the
outer disc, have been reported both in the Milky Way and in external galaxies,
and our results are in full agreement with literature results. We find
azimuthal variations of the oxygen abundance [O/H]. While a large number of
external spirals show negligible azimuthal variations, the Milky Way seems to
be one of the few galaxies with noticeable [O/H] azimuthal asymmetries. They
reach ~0.2 dex in the inner Galaxy and in the outer disc, where they are the
largest, thus supporting similar findings for nearby spiral galaxies as well as
recent 2D chemo-dynamical models.
