Neutron-capture elements in dwarf galaxies III: A homogenized analysis
  of 13 dwarf spheroidal and ultra-faint galaxies
  We present a large homogeneous set of stellar parameters and abundances
across a broad range of metallicities, involving $13$ classical dwarf
spheroidal (dSph) and ultra-faint dSph (UFD) galaxies. In total this study
includes $380$ stars in Fornax, Sagittarius, Sculptor, Sextans, Carina, Ursa
Minor, Draco, Reticulum II, Bootes I, Ursa Major II, Leo I, Segue I, and
Triangulum II. This sample represents the largest, homogeneous, high-resolution
study of dSph galaxies to date. With our homogeneously derived catalog, we are
able to search for similar and deviating trends across different galaxies. We
investigate the mass dependence of the individual systems on the production of
$\alpha$-elements, but also try to shed light on the long-standing puzzle of
the dominant production site of r-process elements. We use data from the Keck
observatory archive and the ESO reduced archive to reanalyze stars from these
$13$ dSph galaxies. We automatize the step of obtaining stellar parameters, but
run a full spectrum synthesis to derive all abundances except for iron. The
homogenized set of abundances yielded the unique possibility to derive a
relation between the onset of type Ia supernovae and the stellar mass of the
galaxy. Furthermore, we derived a formula to estimate the evolution of
$\alpha$-elements. Placing all abundances consistently on the same scale is
crucial to answer questions about the chemical history of galaxies. By
homogeneously analysing Ba and Eu in the 13 systems, we have traced the onset
of the s-process and found it to increase with metallicity as a function of the
galaxy's stellar mass. Moreover, the r-process material correlates with the
$\alpha$-elements indicating some co-production of these, which in turn would
point towards rare core-collapse supernovae rather than binary neutron star
mergers as host for the r-process at low [Fe/H] in the investigated dSph
systems.
