Isotopic ratios and fractionation effects in molecular clouds to constrain the Galactic chemical evolution
Laura Colzi (Centro de Astrobiología (CAB), CSIC-INTA)
Tuesday 03/03/2026 @ 14:00, Sala Antonio Sollima (IV piano Battiferro)
One of the most important tools to investigate the chemical history of our Galaxy and our own Solar System is to measure the isotopic ratios of chemical elements, such as hydrogen (D/H), carbon (12C/13C), or nitrogen (14N/15N). Isotopic ratios measured in molecules 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 begin with a brief overview of key astronomical observations and theoretical chemical models that explore hydrogen, carbon, and nitrogen fractionation. I will then demonstrate how isotopic ratios measured at various Galactic scales - using different radio telescopes, from the central molecular zone (the inner 300 pc) to the outer regions of the Milky Way (up to 20 kpc from the center) - can be employed to trace diverse astrophysical properties. Specifically, I will present how the 12C/13C and 14N/15N ratios, interpreted through Galactic Chemical Evolution models, provide insights into the nucleosynthetic history of the Milky Way.