ABSTRACT Using the Green Bank Telescope, we have obtained accurate measurements of
the 14 N/15 N isotopic ratio in ammonia in two nearby cold, dense molecular clouds …

In light of recent measurement of nitrogen isotope ratios in CN and HCN in several comets,
and the correlation between 15 N excess and the presence of nitrile (-CN) functional groups …

Nitrogen-bearing molecules in cold molecular clouds exhibit a range of isotopic fractionation
ratios and these molecules may be the precursors of 15N enrichments found in comets and …

Context. Ammonia is one of the most reliable tracers of cold dense cores. It is also a minor
constituent of interstellar ices and, as such, one of the important nitrogen reservoirs in the …

The isotopic ratios are diagnostics for the physico-chemical conditions governing molecular
formation. In comets, 14N/15N ratios have been measured from HCN in three comets and …

We describe a mechanism for enhanced nitrogen isotope fractionation in dense molecular
gas where most of the molecules containing carbon and oxygen have condensed on grains …

Determination of the nitrogen isotopic ratios in different bodies of the solar system provides
important information regarding the solar system's origin. We unambiguously identified …

Our aim is to measure the interstellar 14 N/15 N ratio across the Galaxy, to establish a
standard data set on interstellar ammonia isotope ratios, and to provide new constraints on …

Measurements of the isotopic composition of nitrogen in the solar system are summarized.
We show that the 30% change, during the last 3 to 4 billion years, of 15 N 14 N in solar-wind …

Context. Observations of the nitrogen isotopic ratio 14 N/15 N in the interstellar medium are
becoming more frequent thanks to increased telescope capabilities. However, interpreting …