Diversity of Type Ia Supernovae Imprinted in Chemical Abundances
  A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of
their nucleosynthesis on stellar abundances. However, some occasional cases
give birth to stars that avoid enrichment of their chemical compositions by
massive stars and thereby exhibit a SN Ia-like elemental feature including a
very low [Mg/Fe] (~-1). We highlight the elemental feature of Fe-group elements
for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence
of a class of SNe Ia that yield the low abundance ratios of [Cr,Mn,Ni/Fe]. Our
novel models of chemical evolution reveal that our proposed class of SNe Ia
(slow SNe Ia) is associated with ones exploding on a long timescale after their
stellar birth, and gives a significant impact on the chemical enrichment in the
Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is
unseen due to the overwhelming enrichment by the major class of SNe Ia that
explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements.
This nicely explains the different [Cr,Mn,Ni/Fe] features between the two
galaxies as well as the puzzling feature seen in the LMC stars exhibiting very
low Ca but normal Mg abundances. Furthermore, the corresponding channel of slow
SN Ia is exemplified by performing detailed nucleosynthesis calculations in the
scheme of SNe Ia resulting from a 0.8+0.6 solar mass white dwarf merger.
