Contribution Contributed Talk
Hydrogen and Nitrogen isotope fractionation in high-mass star forming regions
The two stable less abundant isotopes of hydrogen and nitrogen, D and 15N, are both enriched in comets and carbonaceous chondrites with respect to the values measured in the proto-solar nebula. This raises the question whether the two enrichments have a common origin, and how both are linked to the past chemical history of the Solar System. I will present new low-angular resolution observations of isotopologues of N2H+ and CN toward dense cores that belong to different evolutionary stages of the massive star-formation process: from massive starless cores, to high-mass protostellar objects, to UC HII regions. These cores represent likely environments similar to that in which our Sun was born, as suggested by recent findings (Ceccarelli et al. 2014, ApJ, 790, L1). Preliminary results indicate (1) a huge spread in the 14N/15N ratio, and (2) a faint anti-correlation between the H/D and 14N/15N ratio. This last result suggests that 15N enrichment is not linked to the parameters that cause D enrichment, in agreement with the prediction by recent chemical models (Roueff et al. 2015, A&A, 576, 99). These models, however, are not able to reproduce the observed large spread in 14N/15N, pointing out that some important routes of nitrogen fractionation could be still missing in the models.