Jose C. APONTE^1,2*, Hannah K. WOODWARD^2,3, Neyda M. ABREU⁴, Jamie E. ELSILA¹, and Jason P. DWORKIN¹
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13216 ]
¹Solar System Exploration Division, Code 691, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
²Department of Chemistry, Catholic University of America, Washington, DC 20064, USA
³Department of Chemistry, University of Reading, Reading RG6 6UA, UK
⁴Earth Science Program, Pennsylvania State University—Du Bois Campus, Du Bois, Pennsylvania 15801, USA
Published by arrangement with John Wiley & Sons

The water‐soluble organic compounds in carbonaceous chondrite meteorites constitute a record of the synthetic reactions occurring at the birth of the solar system and those taking place during parent body alteration and may have been important for the later origins and development of life on Earth. In this present work, we have developed a novel methodology for the simultaneous analysis of the molecular distribution, compound‐specific δ¹³C, and enantiomeric compositions of aliphatic monocarboxylic acids (MCA) extracted from the hot‐water extracts of 16 carbonaceous chondrites from CM, CR, CO, CV, and CK groups. We observed high concentrations of meteoritic MCAs, with total carbon weight percentages which in some cases approached those of carbonates and insoluble organic matter. Moreover, we found that the concentration of MCAs in CR chondrites is higher than in the other meteorite groups, with acetic acid exhibiting the highest concentration in all samples. The abundance of MCAs decreased with increasing molecular weight and with increasing aqueous and/or thermal alteration experienced by the meteorite sample. The δ¹³C isotopic values of MCAs ranged from −52 to +27‰, and aside from an inverse relationship between δ¹³C value and carbon straight‐chain length for C₃–C₆ MCAs in Murchison, the ¹³C‐isotopic values did not correlate with the number of carbon atoms per molecule. We also observed racemic compositions of 2‐methylbutanoic acid in CM and CR chondrites. We used this novel analytical protocol and collective data to shed new light on the prebiotic origins of chondritic MCAs.

Leonardo Krapp¹, Oliver Gressel^1,2, Pablo Benítez-Llambay¹, Turlough P. Downes³, Gopakumar Mohandas^1,2, and Martin E. Pessah¹
Astrophysical Journal 865, 105 Link to Article [DOI: 10.3847/1538-4357/aadcf0]
¹Niels Bohr International Academy, The Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen Ø, Denmark
²Kavli Institute for Theoretical Physics, University of California, Santa Barbara 93106, USA
³Centre for Astrophysics & Relativity, School of Mathematical Sciences, Dublin City University (DCU), Ireland

Imaging of the dust continuum emitted from disks around nearby protostars reveals diverse substructure. In recent years, theoretical efforts have been intensified to investigate how far the intrinsic dynamics of protoplanetary disks (PPDs) can lead to such features. Turbulence in the realm of non-ideal magnetohydrodynamics (MHD) is one candidate for explaining the generation of zonal flows which can lead to local dust enhancements. Adopting a radially varying cylindrical disk model, and considering combinations of vertical and azimuthal initial net flux, we perform 3D non-ideal MHD simulations aimed at studying self-organization induced by the Hall effect in turbulent PPDs. To this end, new modules have been incorporated into the Nirvana-iii and FARGO3D MHD codes. We moreover include dust grains, treated in the fluid approximation, in order to study their evolution subject to the emerging zonal flows. In the regime of a dominant Hall effect, we robustly obtain large-scale organized concentrations in the vertical magnetic field that remain stable for hundreds of orbits. For disks with vertical initial net flux alone, we confirm the presence of zonal flows and vortices that introduce regions of super-Keplerian gas flow. Including a moderately strong net-azimuthal magnetic flux can significantly alter the dynamics, partially preventing the self-organization of zonal flows. For plasma beta-parameters smaller than 50, large-scale, near-axisymmetric structures develop in the vertical magnetic flux. In all cases, we demonstrate that the emerging features are capable of accumulating dust grains for a range of Stokes numbers.

¹Maria Rosa Scicchitano,^1,2,3Daniela Rubatto, ^1,2Jörg Hermann, ⁴Alik S.Majumdar, ⁵Andrew Putnis
Chemical Geology 499, 126-137 Link to Article [https://doi.org/10.1016/j.chemgeo.2018.09.020]
¹Research School of Earth Sciences, Australian National University, Canberra 2601, ACT, Australia
²Institute of Geological Sciences, University of Bern, 3012 Bern, Switzerland
³Institute of Earth Sciences, University of Lausanne, Geopolis, 1015 Lausanne, Switzerland
⁴Geosciences Division, Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, Gujarat, India
⁵The Institute for Geoscience Research, Curtin University, Perth 6845, WA, Australia

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