¹F. Fontani, ¹V. M. Rivilla, ²P. Caselli, ^2,3A. Vasyunin, ⁴A. Palau
The Astrophysical Journal Letters 822,L30 Link to Article [http://dx.doi.org/10.3847/2041-8205/822/2/L30]
¹INAF-Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, I-50125 Firenze, Italy
²Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse, D-85748 Garching, Germany
³Ural Federal University, Ekaterinburg, Russia
⁴Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090 Morelia, Michoacán, México

Phosphorus is a crucial element for the development of life, but so far P-bearing molecules have been detected only in a few astrophysical objects; hence, its interstellar chemistry is almost totally unknown. Here, we show new detections of phosphorus nitride (PN) in a sample of dense cores in different evolutionary stages of the intermediate- and high-mass star formation process: starless, with protostellar objects, and with ultracompact H ii regions. All detected PN line widths are smaller than sime5 km s−1, and they arise from regions associated with kinetic temperatures smaller than 100 K. Because the few previous detections reported in the literature are associated with warmer and more turbulent sources, the results of this work show that PN can arise from relatively quiescent and cold gas. This information is challenging for theoretical models that invoke either high desorption temperatures or grain sputtering from shocks to release phosphorus into the gas phase. Derived column densities are of the order of 1011–12 cm−2, marginally lower than the values derived in the few high-mass star-forming regions detected so far. New constraints on the abundance of phosphorus monoxide, the fundamental unit of biologically relevant molecules, are also given.

¹S. De Angelis, ¹P. Manzari, ¹M.C. De Sanctis, ^1,2E. Ammannito, ^1,3T. Di Iorio
Icarus (in Press) Link to Article [doi:10.1016/j.icarus.2016.07.002]
¹Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, Rome, Italy
²University of California Los Angeles, Earth Planetary and Space Sciences, Los Angeles, CA-90095, USA
³ENEA SSPT-PROTER-OAC, Roma, Italy
Copyright Elsevier

Carbonates and clay minerals are present in Solar System bodies such as Mars and asteroid (1) Ceres. Brucite has been proposed in the recent past to fit absorption features in spectra of Ceres. In this study Visible-Near Infrared reflectance spectroscopic measurements have been performed on brucite-carbonate-clay minerals mixtures, in the 0.2-5.1 μm spectral range. Different sets of three- and two-components mixtures have been prepared using these three fine powdered endmembers, by varying the relative proportions of carbonate, clay and brucite. Spectra have been acquired on the endmembers components separately and on the mixtures. Absorption features diagnostic of the carbonate, clay and brucite phases have been analyzed and band parameters (position, depth, area, width) determined. Several trends and correlations with mineral phase content in each mixture have been investigated, with the aim to determining how endmember components influence the mixture spectra and their minimum detectability threshold. Our results indicate that brucite is detectable in mineral mixtures with carbonates and clays, based on its main absorption features at 0.95, 2.45-2.47 and 3.05 μm. While the 0.95 and 3.05-μm features are only discernible for very high brucite contents in the mixtures, the ∼2.45-μm band turns out to be highly diagnostic, also for very small amounts of brucite (of the order of 10 wt%). These experiments, together with DAWN observations of Ceres, substantially rule out the presence of great amounts of brucite globally distributed on the surface of Ceres.

¹Yoshihiro NAKAMUTA, ²Fumio KITAJIMA, ²Kazuhiko SHIMADA
Journal of Mineralogical and Petrological Sciences Article ID: 150906 Link to Article [doi.org/10.2465/jmps.150906]
¹University Museum, Kyushu University, Hakozaki, Fukuoka 812–8581, Japan
²Faculty of Science, Kyushu University, Motooka, Fukuoka 819–0395, Japan

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^1,2Adrien Denoeud et al. (>10)*
Proceedings of the National Academy of Sciences 113, 7745-7749 Link to Article [doi:10.1073/pnas.1512127113]
¹Laboratoire d’Utilisation de Lasers Intenses – CNRS, Ecole Polytechnique, Commissariat à l’Energie Atomique et aux Energies Alternatives, Université Paris-Saclay, F-91128 Palaiseau Cedex, France;
²Sorbonne Universités, Université Pierre et Marie Curie Paris 6, CNRS, Laboratoire d’Utilisation des Lasers Intenses, place Jussieu, 75252 Paris Cedex 05, France
*Find the extensive, full author and affiliation list on the publishers website

Investigation of the iron phase diagram under high pressure and temperature is crucial for the determination of the composition of the cores of rocky planets and for better understanding the generation of planetary magnetic fields. Here we present X-ray diffraction results from laser-driven shock-compressed single-crystal and polycrystalline iron, indicating the presence of solid hexagonal close-packed iron up to pressure of at least 170 GPa along the principal Hugoniot, corresponding to a temperature of 4,150 K. This is confirmed by the agreement between the pressure obtained from the measurement of the iron volume in the sample and the inferred shock strength from velocimetry deductions. Results presented in this study are of the first importance regarding pure Fe phase diagram probed under dynamic compression and can be applied to study conditions that are relevant to Earth and super-Earth cores.

¹Suniti Karunatillake, ²James J. Wray, ^3,4Olivier Gasnault, ⁵Scott M. McLennan, ⁵A. Deanne Rogers, ⁶Steven W. Squyres, ⁷William V. Boynton, ⁸J. R. Skok, ¹Nicole E. Button, ¹Lujendra Ojha
Journal of Geophysical Research (Planets) (in Press) Link to Article [DOI: 10.1002/2016JE005016]
¹Geology and Geophysics, Louisiana State University, Baton Rouge, LA, USA
²Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
³Université de Toulouse [UPS; OMP; IRAP], Toulouse, France
⁴CNRS [UMR 5277], Institut de Recherche en Astrophysique et Planétologie, BP, Toulouse Cedex 4, France
⁵Department of Geosciences, Stony Brook University, Stony Brook, New York, USA
⁶Department of Astronomy, Cornell University, Ithaca, New York, USA
⁷Department of Planetary Sciences, University of Arizona, AZ, USA
⁸SETI institute, CA, USA
⁹Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
Published by arrangement with John Wiley & Sons

Midlatitudinal hydrated sulfates on Mars may influence brine pH, atmospheric humidity, and collectively water activity. These factors affect the habitability of the planetary subsurface and the preservation of relict biomolecules. Regolith at grain sizes smaller than gravel, constituting the bulk of the martian subsurface at regional scales, may be a primary repository of chemical alteration, mechanical alteration, and biosignatures. The Mars Odyssey Gamma Ray Spectrometer with hundreds of kilometers of lateral resolution and compositional sensitivity to decimeter depth provides unique insight into this component of the regolith, which we call soil. Advancing the globally compelling association between H2O and S established by our previous work [Karunatillake et al., 2014], we characterize latitudinal variations in the association between H and S, as well as in the hydration state of soil. Represented by H2O:S molar ratios, the hydration state of candidate sulfates increases with latitude in the northern hemisphere. In contrast, hydration states generally decrease with latitude in the south. Furthermore, we observe that H2O concentration may affect the degree of sulfate hydration more than S concentration. Limited H2O availability in soil-atmosphere exchange and in subsurface recharge could explain such control exerted by H2O on salt hydration. Differences in soil thickness, ground ice table depths, atmospheric circulation, and insolation may contribute to hemispheric differences in the progression of hydration with latitude. Our observations support chemical association of H2O with S in the southern hemisphere as suggested by Karunatillake et al. [2014], including the possibility of Fe-sulfates as a key mineral group.

¹Alessandro Maturilli, ¹Jörn Helbert, ¹Sabrina Ferrari, ²Björn Davidsson, ¹Mario D’Amore
Earth, Planets and Space 68, 113 Link to Article [DOI: 10.1186/s40623-016-0489-y]
¹Institute of Planetary Research, German Aerospace Center DLR
²Department of Physics and Astronomy, Uppsala University

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¹Romy D. Hanna,²Victoria E. Hamilton, ²Nathaniel E. Putzig
Journal of Geophysical Research (Planets) Link to Article [DOI: 10.1002/2015JE004924]
¹Jackson School of Geological Sciences, University of Texas, Austin, TX
²Department of Space Studies, Southwest Research Institute, Boulder, C
Published by arrangement with John Wiley & Sons

We examine four olivine-bearing regions at a variety of spatial scales with TIR, VNIR, and visible imagery data to investigate the hypothesis that the relationship between olivine abundance and thermal inertia (i.e., effective particle size) can be used to infer the occurrence of olivine chemical alteration during sediment production on Mars. As in previous work, Nili Fossae and Isidis Planitia show a positive correlation between thermal inertia and olivine abundance in TES and THEMIS data, which could be interpreted as indicating olivine chemical weathering. However, geomorphological analysis reveals that relatively olivine-poor sediments are not derived from adjacent olivine-rich materials, and therefore chemical weathering cannot be inferred based on the olivine-thermal inertia relationship alone. We identify two areas (Terra Cimmeria and Argyre Planitia) with significant olivine abundance and thermal inertias consistent with sand, but no adjacent rocky (parent) units having even greater olivine abundances. More broadly, global analysis with TES reveals that the most typical olivine abundance on Mars is ~5-7% and that olivine-bearing (5-25%) materials have a wide range of thermal inertias, commonly 25-600 J · m-2 · K-1 · s-1/2. TES also indicates that the majority of olivine-rich (>25%) materials have apparent thermal inertias less than 400 J · m-2 · K-1 · s-1/2. In summary, we find that the relationship between thermal inertia and olivine abundance alone cannot be used in infer olivine weathering in the examined areas, that olivine-bearing materials have a large range of thermal intertias, and therefore, that a complex relationship between olivine abundance and thermal inertia exists on Mars.

¹John P. Breen,^2,3Alan E. Rubin,^1,2,3John T. Wasson
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.12685]
¹Department of Chemistry and Biochemistry, University of California, Los Angeles, California, USA
²Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA
³Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California, USA
Published by arrangement with John Wiley & Sons

Group-IIIE iron meteorites can be ordered into four categories reflecting increasing degrees of shock alteration. Weakly shocked samples (Armanty, Colonia Obrera, Coopertown, Porto Alegre, Rhine Villa, Staunton, and Tanokami Mountain) have haxonite within plessite, unrecrystallized kamacite grains containing Neumann lines or possessing the ɛ structure, and sulfide inclusions typically consisting of polycrystalline troilite with daubréelite exsolution lamellae. The only moderately shocked sample is NWA 4704, in which haxonite has been partially decomposed to graphite; the majority of the kamacite in NWA 4704 is recrystallized, and its sulfide inclusions were partly melted. Strongly shocked samples (Cachiyuyal, Kokstad, and Paloduro) contain graphite and no haxonite, suggesting that pre-existing haxonite fully decomposed. Also present in these rocks are recrystallized kamacite and melted troilite. Residual heat from the impact caused annealing and recrystallization of kamacite as well as the decomposition of haxonite into graphite. Severely shocked samples (Aliskerovo and Willow Creek) have sulfide-rich assemblages consisting of fragmental and subhedral daubréelite crystals, 1–4 vol% spidery troilite filaments, and 30–50 vol% low-Ni kamacite grains, some of which contain up to 6.0 wt% Co; haxonite in these inclusions has fully decomposed to graphite. The wide range of impact effects in IIIE irons is attributed to one or more major collision(s) on the parent asteroid that affected different group members to different extents depending on their proximity to the impact point.

¹Wataru Fujiya, ²Peter Hoppe,^2,3Ulrich Ott
Meteoritics & Planetary Science (in Press)        Link to Article [DOI: 10.1111/maps.12686]
¹College of Science, Ibaraki University, Ibaraki, Japan
²Max Planck Institute for Chemistry, Mainz, Germany
³University of West Hungary, Szombathely, Hungary
Published by arrangement with John Wiley & Sons

We report the B abundances and isotopic ratios of two olivine grains from the S-type asteroid Itokawa sampled by the Hayabusa spacecraft. Olivine grains from the Dar al Gani (DaG) 989 LL6 chondrite were used as a reference. Since we analyzed polished thin sections in both cases, we expect the contribution from the solar wind B (rich in 10B) to be minimal because the solar wind was implanted only within very thin layers of the grain surface. The Itokawa and DaG 989 olivine grains have homogeneous B abundances (~400 ppb) and 11B/10B ratios compatible with the terrestrial standard and bulk chondrites. The observed homogeneous B abundances and isotopic ratios of the Itokawa olivine grains are likely the result of thermal metamorphism which occurred in the parent asteroid of Itokawa, which had a similar composition as LL chondrites. The chondritic B isotopic ratios of the Itokawa samples suggest that they contain little cosmogenic B (from cosmic-ray spallation reactions) rich in 10B. This observation is consistent with the short cosmic-ray exposure ages of Itokawa samples inferred from the small concentrations of cosmogenic 21Ne. If other Itokawa samples have little cosmogenic B as well, the enrichment in 10B found previously on the surface of another Itokawa particle (as opposed to the bulk grain study here) may be attributed to implanted solar wind B.

^1,2J. A. Arnold, ¹T. D. Glotch, ³P. G. Lucey, ⁴E. Song,^2,5I. R. Thomas, ²N. E. Bowles, ⁶B. Greenhagen
Journal of Geophysical Research Planets (in Press) Link to Article [DOI: 10.1002/2015JE004874]
¹Stony Brook University, Stony Brook, NY
²Oxford University, Oxford, UK
³Hawaii Institute of Geophysics and Planetology, University of Hawaii, Honolulu, HI
⁴Jet Propulsion Laboratory, Pasadena, CA
⁵Belgian Institute for Space Aeronomy, Brussels, Belgium
⁶John Hopkins University Applied Physics Laboratory, Laurel, MD
Published by arrangement with John Wiley & Sons

We place upper limits on lunar olivine abundance using mid infrared (5-25 µm) (MIR) data from the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer Experiment (Diviner) along with effective emissivity spectra of mineral mixtures in a simulated lunar environment. Olivine-bearing, pyroxene-poor lithologies have been identified on the lunar surface with visible-near infrared (VNIR) observations. Since the Kaguya Spectral Profiler (SP) VNIR survey of olivine-rich regions [Yamamoto et al., 2010] is the most complete to date, we focus this work on exposures identified by that study. We first confirmed the locations with VNIR data from the Moon Mineralogy Mapper (M3) instrument. We then developed a Diviner olivine index from our laboratory data which, along with M3 and Lunar Reconnaissance Orbiter Camera (LROC) wide angle camera (WAC) data, was used to select the geographicarea over which Diviner emissivity data were extracted. We calculate upper limits on olivine abundance for these areas using laboratory emissivity spectra of anorthite-forsterite mixtures acquired under lunar-like conditions.

We find that these exposures have widely varying olivine content. In addition, after applying an albedo-based space weathering correction to the Diviner data, we find that none of the areas are unambiguously consistent with concentrations of forsterite exceeding 90 wt%, in contrast to the higher abundance estimates derived from VNIR data.