Interstellar Dust in the Solar System

1,2Sterken, V.J.,3Westphal, A.J.,4Altobelli, N.,5Malaspina, D.,6,7Postberg, F.
Space Science Reviews 215, 43 Link to Article [DOI: 10.1007/s11214-019-0607-9]
1Astronomisches Institut Universität Bern (AIUB), Bern, Switzerland
2Institute of Applied Physics (IAP), University of Bern, Bern, Switzerland
3Space Sciences Laboratory, University of California at Berkeley, Berkeley, United States
4European Space Agency, ESAC, Madrid, Spain
5LASP, University of Colorado, Boulder, United States
6Institute of Earth Sciences, University of Heidelberg, Heidelberg, Germany
7Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany

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The Analysis of Resistivity Characteristics and Mineral Composition of Qinghai Meteorolite

1Jianguo Wang,2Lei Zhang,2Li Zhong
IOP Conference Series: Earth and Environmental Science 310, 032004 Link to Article [DOI https://doi.org/10.1088/1755-1315/310/3/032004]
1Department of Geological Engineering, Qinghai University, Xining 810086, China
2TianShi Culture Development Co., Ltd., Xining 810086, China

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Investigation of the kieserite–szomolnokite solid-solution series, (Mg,Fe)SO4·H2O, with relevance to Mars: Crystal chemistry, FTIR, and Raman spectroscopy under ambient and martian temperature conditions

1Dominik Talla,1Manfred Wildner
American Mineralogist 104, 1732-1749 Link to Article [https://doi.org/10.2138/am-2019-6983]
1Institut für Mineralogie und Kristallographie, Althanstraße 14, 1090 Wien, Austria
Copyright: The Mineralogical Society of America

The investigation of hydrous sulfate deposits and sulfate-cemented soils on the surface of Mars is one of the important topics in the recent scientific endeavor to retrieve detailed knowledge about the planetary water budget and surface weathering processes on our neighbor planet. Orbital visible/near-IR spectra of the surface of Mars indicate kieserite, MgSO4·H2O, as a dominant sulfate species at lower latitudes. However, given the Fe-rich composition of the martian surface, it is very probable that its actual composition lies at an intermediate value along the solid-solution series between the kieserite and szomolnokite (FeSO4·H2O) end-members. Despite the known existence of significant lattice parameter changes and spectral band position shifts between the two pure end-members, no detailed crystal chemical and spectroscopic investigation along the entire kieserite–szomolnokite solid solution range has been done yet.
The present work proves for the first time the existence of a continuous kieserite–szomolnokite solid-solution series and provides detailed insight into the changes in lattice parameters, structural details, and positions of prominent bands in FTIR (5200–400 cm–1) and Raman (4000–100 cm–1) spectra in synthetic samples as the Fe/Mg ratio progresses, at both ambient as well as Mars-relevant lower temperatures. Additionally, an UV-Vis-NIR (29 000–3500 cm–1) crystal field spectrum of szomolnokite is presented to elucidate the influence of Fe2+-related bands on the overtone- and combination mode region.
The kieserite–szomolnokite solid-solution series established in this work shows Vegard-type behavior, i.e., lattice parameters as well as spectral band positions change along linear trends. The detailed knowledge of these trends enables semi-quantitative estimations of the Fe/Mg ratio that can be applied to interpret martian monohydrated sulfates in data from remote sensing missions on a global scale as well as from in situ rover measurements. Given the knowledge of the surface temperature during spectral measurements, the established temperature behavior allows quantitative conclusions concerning the Fe/Mg ratio. Our understanding of the kieserite–szomolnokite solid-solution series will be well applicable to the Mars 2020 and ExoMars 2020 rover missions that will focus on near IR (0.9 to 3.5 μm) and, for the first time on Mars, Raman spectroscopy.

Molecular Cloud Origin for Oxygen Isotopic Heterogeneity Recorded by a Primordial Spinel-rich Refractory Inclusion

1Justin I. Simon,1,2D. Kent Ross,1,3Ann N. Nguyen,4Steven B. Simon,1Scott Messenger
The Astrophysical Journal, Letters 884, L29 Link to Article [DOI
https://doi.org/10.3847/2041-8213/ab43e4]
1Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, TX 77058, USA
2University of Texas at El Paso/Jacobs-JETS, Houston, TX 77058, USA
3Jacobs-JETS, Houston, TX 77058, USA
4Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131, USA

A spinel-rich, layered calcium- aluminum-rich spherule from the MIL 090019 CO3 chondrite contains a spinel core with a relatively 16O-rich (Δ17O ~ −18‰) and mass-fractionated oxygen isotopic composition surrounded by minerals, including spinel, that are relatively 16O-poor (Δ17O ~ −7‰), which are in turn surrounded by layers of 16O-enriched silicates (Δ17O ~ −17‰). Inclusions with refractory mineral assemblages such as this one are proposed to record inner nebula processes during the earliest epoch of solar nebula evolution. Mineralogical and textural analyses indicate that this primordial particle formed by high-temperature gas–solid reactions, partial melting, evaporation, and condensation. The radially distributed oxygen isotopic heterogeneity measured among multiple occurrences of several minerals, including spinel, requires the existence of 16O-poor gas at the beginning of solar system formation, 105 yr earlier than it can be produced by photochemical self-shielding in the solar nebula and introduced to the inner protoplanetary disk.

Formation of Interstellar C60 from Silicon Carbide Circumstellar Grains

1J. J. Bernal,2P. Haenecour,3J. Howe,2,4T. J. Zega,5S. Amari,1,6,7L. M. Ziurys
The Astrophysical Journal, Letters 883, L43 Link to Article [DOI
https://doi.org/10.3847/2041-8213/ab4206]
1Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
2Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Boulevard, Tucson, AZ 85721, USA
3Department of Materials Science and Engineering, and Department of Chemical Engineering and Applied Chemistry, University of Toronto, Canada
4Department of Materials Science and Engineering, University of Arizona, USA
5Physics Department and McDonnell Center for the Space Sciences, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
6Department of Astronomy, Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
7Arizona Radio Observatory, Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA

We have conducted laboratory experiments with analog crystalline silicon carbide (SiC) grains using transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS). The 3C polytype of SiC was used—the type commonly produced in the envelopes of asymptotic giant branch (AGB) stars. We rapidly heated small (~50 nm) synthetic SiC crystals under vacuum to ~1300 K and bombarded them with 150 keV Xe ions. TEM imaging and EELS spectroscopic mapping show that such heating and bombardment leaches silicon from the SiC surface, creating layered graphitic sheets. Surface defects in the crystals were found to distort the six-membered rings characteristic of graphite, creating hemispherical structures with diameters matching that of C60. Such nonplanar features require the formation of five-membered rings. We also identified a circumstellar grain, preserved inside the Murchison meteorite, that contains the remnant of an SiC core almost fully encased by graphite, contradicting long-standing thermodynamic predictions of material condensation. Our combined laboratory data suggest that C60 can undergo facile formation from shock heating and ion bombardment of circumstellar SiC grains. Such heating/bombardment could occur in the protoplanetary nebula phase, accounting for the observation of C60 in these objects, in planetary nebulae (PNs) and other interstellar sources receiving PN ejecta. The synthesis of C60 in astronomical sources poses challenges, as the assembly of 60 pure carbon atoms in an H-rich environment is difficult. The formation of C60 from the surface decomposition of SiC grains is a viable mechanism that could readily occur in the heterogeneous, hydrogen-dominated gas of evolved circumstellar shells.

The Dawn of Dust Astronomy

1,2Grün, E.,3Krüger, H.,4Srama, R.
Space Science Reviews 215, 46 Link to Article [DOI: 10.1007/s11214-019-0610-1]
1Max-Planck-Institut für Kernphysik, Heidelberg, Germany
2LASP, University of Colorado, Boulder, CO, United States
3Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany
4Institut für Raumfahrtsysteme, Universität Stuttgart, Stuttgart, Germany

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