Evidence for an early nitrogen isotopic evolution in the solar nebula from volatile analyses of a CAI from the CV3 chondrite NWA 8616

Synthesis of refractory organic matter in the ionized gas phase of the solar nebula

“…While some of the solar system objects and reservoirs present H and N isotope correlations that suggest a common ion–molecule reaction origin, in other cases including meteoritic organics, excesses of 15 N and of D are uncorrelated, pointing to different isotope fractionation mechanisms. The 15 N enrichments of solids in the inner solar system might have been very rapid, possibly 150 kya or less after the start of solar system condensation ( 48 ). The D enrichments could have then postdated the formation of organic precursors ( 5 ).…”

Nitrogen isotope variations in the Solar System

“…In contrast, the 15 N enrichments above the kinetic isotope fractionation line require preferential N isotope fractionation compared to D/H. This could result from photodissociation of protosolar N 2 by UV light 74 , or from self-shielding 95 (Box 2), and appears to have occurred within the first few tens to hundreds thousands of years after Solar System formation 71 . Similarly, the enrichment in the heavy isotopes of oxygen ( 17 O and 18 O) relative to the major, light isotope ( 16 O) recorded by Solar System solids compared to the protosolar oxygen isotope composition may be the result of illumination of the PSN gas by solar/ stellar photons 95 .…”

“…A mechanism is required to explain the progressive temporal and spatial evolution of nitrogen isotopes in the Solar System. The recent detection of 15 N-enriched nitrogen in a CAI, which last interacted with the nebular gas ≤0.15 Ma as shown by the 26 Al-26 Mg chronometer, suggests that at least some regions of the disk were driven toward isotopically heavy values within the first few hundred kyr after Solar System formation 71 . The nature of the fractionating processes is still a matter of debate, and several processes might have played a role (Boxes 2 and 3).…”

A primordial 15N-depleted organic component detected within the carbonaceous chondrite Maribo

“…Recently, isotopic analyses of nitrides from different chondrites generally supported such a sequence 57 , and a similar gradient has been observed around other stellar systems 22 . It is also possible that these materials can be distributed to different locations around the solar system, based on the observation of a 15 N-rich CAI in a meteorite 58 . It is also interesting to note in this respect that 15 N-depleted OM has not been reported yet within primitive IDPs, which are thought to originate in cometary, i.e., outer solar system bodies.…”