[$\alpha$/Fe] traced by H ii regions from the CALIFA survey: The
  connection between morphology and chemical abundance patterns
  Differential enrichment between $\alpha$- and Fe-peak elements is known to be
strongly connected with the shape of the star formation history (SFH), the star
formation efficiency (SFE), the inflow and outflow of material, and even the
shape of the Initial Mass Function (IMF). However, beyond the Local Group
detailed explorations are mostly limited to early-type galaxies due to the lack
of a good proxy for [$\alpha$/Fe] in late-type ones, limiting our understanding
of the chemical enrichment process. We intent to extend the explorations of
[$\alpha$/Fe] to late-type galaxies, in order to understand the details of the
differential enrichment process. We compare the gas phase oxygen abundance with
the luminosity weighted stellar metallicity in an extensive catalog of
$\sim$25,000 H ii regions extracted from the Calar Alto Legacy Integral Field
Area (CALIFA) survey, an exploration using integral field spectroscopy of
$\sim$900 galaxies, covering a wide range of masses and morphologies. This way
we define [O/Fe] as the ratio between both parameters, proposing it as an
indirect proxy of the [$\alpha$/Fe] ratio. Results. We illustrate how the
[O/Fe] parameter describes the chemical enrichment process in spiral galaxies,
finding that: (i) it follows the decreasing pattern with [Fe/H] reported for
the [$\alpha$/Fe] ratio and (ii) its absolute scale depends of the stellar mass
and the morphology. We reproduce both patterns using two different chemical
evolution models (ChEM), considering that galaxies with different stellar mass
and morphology present (i) different SFHs, SFEs and different inflow/outflow
rates, or (ii) a different maximum stellar mass cut for the IMF. We will
explore the differential chemical enrichment using this new proxy galaxy by
galaxy and region by region in further studies.
