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Based on the recently developed numerical approach to understand
the formation and the chemical evolution of the milky-way galaxy in the solar neighborhood
we study the influence of the supernova type SN Ia rates on the galactic chemical
evolution. Supernova SN Ia plays an important role in producing the iron inventory
of the galaxy. We also study the dependence of the chemical evolution on the star
formation rate prevailing during the initial one billion years of the evolution
of the galaxy. This era marks the formation of the galactic halo and the thick disk.
A comparison of the elemental abundance distributions of the dwarf stars in the
solar neighborhood is made among the various models simulated in the present work.
In order to explain the majority of the observed elemental evolutionary trends,
specifically those related with the galactic evolution of iron and oxygen, it would
be essential to incorporate a major component of prompt SN Ia to the galactic evolution.
The prompt SN Ia would produce significant fraction of SN Ia within the initial
~100 million years from the time of star formation. The essential requirement of
prompt SN Ia would result in a significant enhancement of SN Ia rates during the
earliest epoch of the galaxy. The elemental evolutionary trends also favor an enhancement
in the star formation rate during the initial one billion years of the galaxy at
least by a factor of three compared to the trend prevailing during the latter evolutionary
time of the galaxy.
The manner the galaxy
accretes matter, along with the star formation rates at different epochs,
influences the evolution of the stable isotopic inventories of the galaxy. A
detailed analysis is presented here to study the dependence of the galactic
chemical evolution on the accretion scenario of the galaxy along with the star
formation rate during the early accretionary phase of the galactic thick disk
and thin disk. Our results indicate that a rapid early accretion of the galaxy
during the formation of the galactic thick disk along with an enhanced star
formation rate in the early stages of the galaxy accretion could explain the
majority of the galactic chemical evolution trends of the major elements.
Further, we corroborate the recent suggestions regarding the formation of a
massive galactic thick disk rather than the earlier assumed low mass thick