Speaker
Description
Isotopic ratios (e.g. 12C/13C and 14N/15N ratios) measured within interstellar molecular clouds
depend on the chemical evolution of the galaxy due to stellar nucleosynthesis, and thus they can
provide unique constraints to the history of star formation in galaxies. Moreover, isotopic ratios
also depend on local chemical fractionation effects, which are closely connected to the physical
conditions of molecular clouds and cores (e.g. density and temperature, or UV radiation field). In
this talk, I will review the main observed galactocentric trends of isotopic ratios, and I will introduce
the CHEMOUT (CHEMical complexity in star-forming regions of the OUTer Galaxy) project.
The latter include observations of a sample of 35 high-mass star-forming cores at Galactocentric
distances up to about 23 kpc obtained with the IRAM 30m telescope. The study of isotopic ratios
with these recent observations towards star-forming regions located in the outer Galaxy allow us
for the first time to extend the prediction of Galactic Chemical Evolution models to these distances
