  We examine the contribution of electron-capture supernovae (ECSNe), low-mass
SNe from collapsing Fe cores (FeCCSNe), and rotating massive stars to the
chemical composition of the Galaxy. Our model includes contributions to
chemical evolution from both thermonuclear ECSNe (tECSNe) and gravitational
collapse ECSNe (cECSNe). We show that if ECSNe are predominantly gravitational
collapse SNe but about 15% are partial thermonuclear explosions, the model is
able to reproduce the solar abundances of several important and problematic
isotopes including $^{48}$Ca, $^{50}$Ti and $^{54}$Cr together with $^{58}$Fe,
$^{64}$Ni, $^{82}$Se and $^{86}$Kr and several of the Zn--Zr isotopes. A model
in which no cECSNe occur, only tECSNe with low-mass FeCCSNe or rotating massive
stars, proves also very successful at reproducing the solar abundances for
these isotopes. Despite the small mass range for the progenitors of ECSNe and
low-mass FeCCSNe, the large production factors suffice for the solar inventory
of the above isotopes. Our model is compelling because it introduces no new
tensions with the solar abundance distribution for a Milky Way model -- only
tending to improve the model predictions for several isotopes. The proposed
astrophysical production model thus provides a natural and elegant way to
explain one of the last uncharted territories on the periodic table of
astrophysical element production.
