Our astrochemical heritage
  Our Sun and planetary system were born about 4.5 billion years ago. How did
this happen and what is our heritage from these early times? This review tries
to address these questions from an astrochemical point of view. On the one
hand, we have some crucial information from meteorites, comets and other small
bodies of the Solar System. On the other hand, we have the results of studies
on the formation process of Sun-like stars in our Galaxy. These results tell us
that Sun-like stars form in dense regions of molecular clouds and that three
major steps are involved before the planet formation period. They are
represented by the pre-stellar core, protostellar envelope and protoplanetary
disk phases. Simultaneously with the evolution from one phase to the other, the
chemical composition gains increasing complexity.
  In this review, we first present the information on the chemical composition
of meteorites, comets and other small bodies of the Solar System, which is
potentially linked to the first phases of the Solar System's formation. Then we
describe the observed chemical composition in the pre-stellar core,
protostellar envelope and protoplanetary disk phases, including the processes
that lead to them. Finally, we draw together pieces from the different objects
and phases to understand whether and how much we inherited chemically from the
time of the Sun's birth.
