The hELENa project - II. Abundance distribution trends of early-type
  galaxies: from dwarfs to giants
  In this second paper of T$h$e role of $E$nvironment in shaping $L$ow-mass
$E$arly-type $N$earby g$a$laxies (hELENa) series we study [Mg/Fe] abundance
distribution trends of early-type galaxies observed with the SAURON integral
field unit, spanning a wide range in mass and local environment densities: 20
low-mass early-types (dEs) of Sybilska et al. (2017) and 258 massive early
types (ETGs) of the $ATLAS^{3D}$ project, all homogeneously reduced and
analyzed. We show that the [Mg/Fe] ratios scale with velocity dispersion
($\sigma$) at fixed [Fe/H] and that they evolve with [Fe/H] along similar paths
for all early-types, grouped in bins of increasing local and global {$\sigma$},
as well as the second velocity moment $V_{rms}$, indicating a common inside-out
formation pattern. We then place our dEs on the [Mg/Fe] $vs.$ [Fe/H] diagram of
Local Group galaxies and show that dEs occupy the same region and show a
similar trend line slope in the diagram as the high-metallicity stars of the
Milky Way and the Large Magellanic Cloud. This finding extends the similar
trend found for dwarf spheroidal $vs.$ dwarf irregular galaxies and supports
the notion that dEs have evolved from late-type galaxies that have lost their
gas at a point of their evolution, which likely coincided with them entering
denser environments.
