Astrochemistry During the Formation of Stars
  Star-forming regions show a rich and varied chemistry, including the presence
of complex organic molecules - both in the cold gas distributed on large
scales, and in the hot regions close to young stars where protoplanetary disks
arise. Recent advances in observational techniques have opened new
possibilities for studying this chemistry. In particular, the Atacama Large
Millimeter/submillimeter Array (ALMA) has made it possible to study
astrochemistry down to Solar System size scales, while also revealing molecules
of increasing variety and complexity. In this review, we discuss recent
observations of the chemistry of star-forming environments, with a particular
focus on complex organic molecules, taking context from the laboratory
experiments and chemical models that they have stimulated. The key takeaway
points are: The physical evolution of individual sources plays a crucial role
in their inferred chemical signatures, and remains an important area for
observations and models to elucidate. Comparisons of the abundances measured
toward different star-forming environments (high-mass versus low-mass, Galactic
center versus Galactic disk) reveal a remarkable similarity, an indication that
the underlying chemistry is relatively independent of variations in their
physical conditions. Studies of molecular isotopologs in star-forming regions
provide a link with measurements in our own Solar System, and thus may shed
light on the chemical similarities and differences expected in other planetary
systems.
