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            N-Poor Isotopic Composition for the Solar System As Shown by Genesis Solar Wind Samples

Marty, Bernard; Chaussidon, M.; Wiens, R. C.; Jurewicz, A. J. G.; Burnett, D. S.

doi:10.1126/science.1204656

Cited by 274 publications

(265 citation statements)

References 48 publications

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“…For species containing two nitrogen atoms, the ratio has been multiplied by two to emphasize that a ratio of 220 indeed means no fractionation for such species. ‡: Fractionation level, or normalized isotopic ratio, is the isotopic ratio normalized to the protosolar value 14 N/ 15 N=440 from Marty et al (2011). Depletion factor δ 15 = 1000 × [R ATM /R − 1], where the reference value R ATM = 272 is the isotopic ratio of the Earth atmosphere.…”

Section: Discussionmentioning

confidence: 99%

“…However, secondary photons, which result from the fluorescence of H 2 molecules excited by collisions with the electrons produced by cosmicrays are explicitly taken into account and are responsible for a significant fraction of the ionisation. The initial abundances are given in Table A.1, where an elemental isotopic ratio of nitrogen R 0 = 440 was adopted (Marty et al 2011). …”

Section: Model Calculationsmentioning

confidence: 99%

“…The Genesis mission has recently allowed Marty et al (2011) to measure the nitrogen isotopic ratio in the solar wind, yielding 14 N/ 15 N = 441 ± 5 for the protosolar nebula. This value is significantly larger than the terrestrial value of 272.…”

Section: Introductionmentioning

confidence: 99%

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The CN/C¹⁵N isotopic ratio towards dark clouds

Hily-Blant

Forêts

Fauré

et al. 2013

A&A

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Understanding the origin of the composition of solar system cosmomaterials is a central question, not only in the cosmochemistry and astrochemistry fields, and requires various approaches to be combined. Measurements of isotopic ratios in cometary materials provide strong constraints on the content of the protosolar nebula. Their relation with the composition of the parental dark clouds is, however, still very elusive. In this paper, we bring new constraints based on the isotopic composition of nitrogen in dark clouds, with the aim of understanding the chemical processes that are responsible for the observed isotopic ratios. We have observed and detected the fundamental rotational transition of C 15 N towards two starless dark clouds, L1544 and L1498. We were able to derive the column density ratio of C 15 N over 13 CN towards the same clouds, and obtain the CN/C 15 N isotopic ratios, which were found to be 500 ± 75 for both L1544 and L1498. These values are therefore marginally consistent with the protosolar value of 441. Moreover, this ratio is larger than the isotopic ratio of nitrogen measured in HCN. In addition, we present model calculations of the chemical fractionation of nitrogen in dark clouds, which make it possible to understand how CN can be deprived of 15 N and HCN can simultaneously be enriched in heavy nitrogen. The non-fractionation of N 2 H + , however, remains an open issue and we propose some chemical way of alleviating the discrepancy between model predictions and the observed ratios.

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Section: Discussionmentioning

confidence: 99%

Section: Model Calculationsmentioning

confidence: 99%

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The CN/C¹⁵N isotopic ratio towards dark clouds

Hily-Blant

Forêts

Fauré

et al. 2013

A&A

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“…2). The analysis of Genesis solar wind samples (Marty et al 2011), considered as representative of the protosolar nebula, provided a 14 N/ 15 N ratio of 441 ± 5. This value is in agreement with the in situ measurements made in the ammonia of Jupiter's atmosphere (Fouchet et al 2004) which probably comes from primordial N 2 (Owen et al 2001).…”

Section: Nitrogen Isotopesmentioning

confidence: 99%

Cometary Isotopic Measurements

et al. 2015

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“…They specifically discussed the role of the atomic-to-molecular nitrogen ratio in the fractionation process and the possible link between nitrogen hydrides and CN containing molecules (nitriles). The corresponding observations are sparse, however, and difficult because the elemental 14 N/ 15 N ratio is high (441 ± 5), as determined by the recent Genesis solar wind sampling measurement (Marty et al 2011), and is assumed to hold in the local ISM.…”

Section: Introductionmentioning

confidence: 99%

Isotopic fractionation of carbon, deuterium, and nitrogen: a full chemical study

Roueff

Loison

Hickson

2015

A&A

171

349

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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. The 14 N/ 15 N ratio is difficult to measure directly for molecules containing carbon. Aims. Using a time-dependent gas-phase chemical model, we check the underlying hypothesis that the 13 C/ 12 C ratio of nitriles and isonitriles is equal to the elemental value. Methods. We built a chemical network that contains D, 13 C, and 15 N molecular species after a careful check of the possible fractionation reactions at work in the gas phase. Results. Model results obtained for two different physical conditions that correspond to a moderately dense cloud in an early evolutionary stage and a dense, depleted prestellar core tend to show that ammonia and its singly deuterated form are somewhat enriched in 15 N, which agrees with observations. The 14 N/ 15 N ratio in N 2 H + is found to be close to the elemental value, in contrast to previous models that obtain a significant enrichment, because we found that the fractionation reaction between 15 N and N 2 H + has a barrier in the entrance channel. The high values of the N 2 H + / 15 NNH + and N 2 H + /N 15 NH + ratios derived in L1544 cannot be reproduced in our model. Finally, we find that nitriles and isonitriles are in fact significantly depleted in 13 C, thereby challenging previous interpretations of observed C 15 N, HC 15 N, and H 15 NC abundances from 13 C containing isotopologues.

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A ¹⁵ N-Poor Isotopic Composition for the Solar System As Shown by Genesis Solar Wind Samples

Cited by 274 publications

References 48 publications

The CN/C¹⁵N isotopic ratio towards dark clouds

The CN/C¹⁵N isotopic ratio towards dark clouds

Cometary Isotopic Measurements

Isotopic fractionation of carbon, deuterium, and nitrogen: a full chemical study

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A 15 N-Poor Isotopic Composition for the Solar System As Shown by Genesis Solar Wind Samples

Cited by 274 publications

References 48 publications

The CN/C15N isotopic ratio towards dark clouds

The CN/C15N isotopic ratio towards dark clouds

Cometary Isotopic Measurements

Isotopic fractionation of carbon, deuterium, and nitrogen: a full chemical study

Contact Info

Product

Resources

About

A ¹⁵ N-Poor Isotopic Composition for the Solar System As Shown by Genesis Solar Wind Samples

The CN/C¹⁵N isotopic ratio towards dark clouds

The CN/C¹⁵N isotopic ratio towards dark clouds