Depletion of heavy nitrogen in the cold gas of star-forming regions

@article{Furuya2018DepletionOH,
  title={Depletion of heavy nitrogen in the cold gas of star-forming regions},
  author={Kenji Furuya and Yuri Aikawa},
  journal={arXiv: Astrophysics of Galaxies},
  year={2018}
}
We investigate nitrogen isotope fractionation in forming and evolving molecular clouds using gas-ice astrochemical simulations. We find that the bulk gas can become depleted in heavy nitrogen (15N) due to the formation of 15N-enriched ices. Around the chemical transition from atomic nitrogen to N2, N15N is selectively photodissociated, which results in the enrichment of 15N in atomic nitrogen. As 15N-enriched atomic nitrogen is converted to ammonia ice via grain surface reactions, the bulk gas… 

Figures and Tables from this paper

Chemical nitrogen fractionation in dense molecular clouds
Nitrogen-bearing molecules display variable isotopic fractionation levels in different astronomical environments such as in the interstellar medium or in the Solar system. Models of interstellar
Gas-dust chemistry of volatiles in the star and planetary system formation
Abstract The focus of this work is on two topics: (i) formation of complex organic molecules (COMs) and (ii) isotope fractionation. Various COMs, which are C, H-containing molecules consisting of 6
Isotopic fractionation in interstellar molecules
  • K. Furuya
  • Chemistry, Physics
    Proceedings of the International Astronomical Union
  • 2017
Abstract The level of isotopic fractionation in molecules provides insights into their formation environments and how they formed. In this article, we review hydrogen and nitrogen isotopic
Oxygen fractionation in dense molecular clouds.
We have developed the first gas-grain chemical model for oxygen fractionation (also including sulphur fractionation) in dense molecular clouds, demonstrating that gas-phase chemistry generates
Depletion of 15N in the center of L1544: Early transition from atomic to molecular nitrogen?
We performed sensitive observations of the N15ND+(1–0) and 15NND+(1–0) lines toward the prestellar core L1544 using the IRAM 30 m telescope. The lines are not detected down to 3σ levels in 0.2 km s−1
Multiple nitrogen reservoirs in a protoplanetary disk at the epoch of comet and giant planet formation
The isotopic ratio of nitrogen measured in primitive Solar System bodies shows a broad range of values, the origin of which remains unknown. One key question is whether these isotopic reservoirs of
Exploring the Origins of Earth’s Nitrogen: Astronomical Observations of Nitrogen-bearing Organics in Protostellar Environments
It is not known whether the original carriers of Earth's nitrogen were molecular ices or refractory dust. To investigate this question, we have used data and results of Herschel observations towards
Ice Inheritance in Dynamical Disk Models
The compositions of planet-forming disks are set by a combination of material inherited from the interstellar medium and material reprocessed during disk formation and evolution. Indeed, comets and
Prebiotic Astrochemistry and the Formation of Molecules of Astrobiological Interest in Interstellar Clouds and Protostellar Disks.
TLDR
Because these chemical processes are universal and should occur in these environments wherever they are found, this implies that some of the starting materials for life are likely to be widely distributed throughout the universe.
Interstellar Nitrogen Isotope Ratios: New NH3 Data from the Galactic Center out to the Perseus Arm
  • J. L. Chen, J. S. Zhang, +10 authors Y. P. Zou
  • Physics
    The Astrophysical Journal Supplement Series
  • 2021
Our aim is to measure the interstellar 14N/15N ratio across the Galaxy, to establish a standard data set on interstellar ammonia isotope ratios, and to provide new constraints on the Galactic
...
1
2
...

References

SHOWING 1-10 OF 65 REFERENCES
The End of Interstellar Chemistry as the Origin of Nitrogen in Comets and Meteorites
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 but where N2 remains in
A low fraction of nitrogen in molecular form in a dark cloud
TLDR
It is found that only a small fraction of nitrogen in the gas phase is molecular, with most of it being atomic, which explains the low N2 abundance in comets.
Elemental nitrogen partitioning in dense interstellar clouds
TLDR
It is argued that N2 does not represent the main reservoir species for interstellar nitrogen, and elevated abundances of more labile forms of nitrogen such as NH3 should be present on interstellar ices, promoting the eventual formation of nitrogen-bearing organic molecules.
Nitrogen superfractionation in dense cloud cores
We report new calculations of interstellar 15N-fractionation. Previously, we have shown that large enhancements of 15N/14N can occur in cold, dense gas where CO is frozen out, but that the existence
Revised Models of Interstellar Nitrogen Isotopic Fractionation
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 meteorites.
Isotopic fractionation of carbon, deuterium and nitrogen : a full chemical study
Context. The increased sensitivity and high spectral resolution of millimeter telescopes allow the detection of an increasing number of isotopically substituted molecules in the interstellar medium.
ISOTOPIC ANOMALIES IN PRIMITIVE SOLAR SYSTEM MATTER: SPIN-STATE-DEPENDENT FRACTIONATION OF NITROGEN AND DEUTERIUM IN INTERSTELLAR CLOUDS
Organic material found in meteorites and interplanetary dust particles is enriched in D and 15N. This is consistent with the idea that the functional groups carrying these isotopic anomalies,
Detection of 15NH2D in dense cores : a new tool for measuring the 14N/15N ratio in the cold ISM
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 protosolar
Nitrogen Isotopic Fractionation of Interstellar Nitriles
In light of recent measurement of nitrogen isotope ratios in CN and HCN in several comets, and the correlation between 15N excess and the presence of nitrile (-CN) functional groups in meteoritic
Water deuteration and ortho-to-para nuclear spin ratio of H2 in molecular clouds formed via the accumulation of H I gas
We investigate the water deuteration ratio and ortho-to-para nuclear spin ratio of H2 (OPR(H2)) during the formation and early evolution of a molecular cloud, following the scenario that accretion
...
1
2
3
4
5
...