Isotopic fractionation study towards massive star-forming regions across the Galaxy

Abstract

One of the most important tools to investigate the chemical history of our Galaxy and our own Solar System is to measure the isotopic fractionation of chemical elements. In the present study new astronomical observations devoted to the study of hydrogen and nitrogen fractionation (D/H and 14N/15N ratios) of molecules, towards massive star-forming regions in different evolutionary phases, have been presented. Moreover, a new detailed theoretical study of carbon fractionation, 12C/13C ratios, has been done. One of the main results was the confirmation that the 14N/15N ratio increases with the galactocentric distance, as predicted by stellar nucleosynthesis Galactic chemical evolution models. This work gives new important inputs on the understanding of local chemical processes that favor the production of molecules with different isotopes in star-forming regions.

Nitrogen isotopes in the interstellar medium: A chemical journey across the Galaxy

“…We are now extending this trend towards the outer part of our Galaxy (D GC >12 kpc), also updating GCE models with new stellar yields and approaching distances where CNO isotopes 1 For more information on the observations and the analysis done see [8,9]. in molecular clouds (e.g.…”

“…[19]). In this respect, we have analysed a sample of 87 massive star-forming regions observed with the IRAM 30m radiotelescope 1 . The sources span galactocentric distances, D GC , from 2 up to 12 kpc allowing to study the 14 N/ 15 N ratio of HCN and HNC as a function of D GC (Fig.…”

“…The pink area represents measurements in carbonaceous chondrites, where the lower ones are the so-called "hot-spots". Adapted from[1].…”