Pinghui Huang^1,2,3, Andrea Isella⁴, Hui Li³, Shengtai Li³, and Jianghui Ji¹
Astrophysical Journal 867, 3 Link to Article [DOI: 10.3847/1538-4357/aae317]
¹CAS Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, People’s Republic of China
²University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
³Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁴Department of Physics & Astronomy, Rice University, 6100 Main Street, Houston, TX 77005, USA

Several nearby protoplanetary disks have been observed to display large-scale crescents in the (sub)millimeter dust continuum emission. One interpretation is that these structures correspond to anticyclonic vortices generated by the Rossby wave instability within the gaseous disk. Such vortices have local gas overdensities and are expected to concentrate dust particles with a Stokes number around unity. This process might catalyze the formation of planetesimals. Whereas recent observations showed that dust crescents are indeed regions where millimeter-size particles have abnormally high concentration relative to the gas and smaller grains, no observations have yet shown that the gas within the crescent region counterrotates with respect to the protoplanetary disk. Here we investigate the detectability of anticyclonic features through measurement of the line-of-sight component of the gas velocity obtained with ALMA. We carry out 2D hydrodynamic simulations and 3D radiative transfer calculations of a protoplanetary disk characterized by a vortex created by the tidal interaction with a massive planet. As a case study, the disk parameters are chosen to mimic the IRS 48 system, which has the most prominent crescent observed to date. We generate synthetic ALMA observations of both the dust continuum and ¹²CO emission around the frequency of 345 GHz. We find that the anticyclonic features of the vortex are weak but can be detected if both the source and the observational setup are properly chosen. We provide a recipe for maximizing the probability of detecting such vortex features and present an analysis procedure to infer their kinematic properties.

^1,2Britvin, S.N.,¹Murashko, M.N., ³Vapnik, Y., ¹Polekhovsky, Y.S., ^1,2Krivovichev, S.V., ¹Vereshchagin, O.S., ⁴Vlasenko, N.S., ⁴Shilovskikh, V.V., ¹Zaitsev, A.N.
Physics and Chemistry of Minerals (in Press) Link to Article [DOI: 10.1007/s00269-018-1008-4]
¹Institute of Earth Sciences, Saint-Petersburg State University, Universitetskaya Nab. 7/9, St. Petersburg, 199034, Russian Federation
²Nanomaterials Research Center, Kola Science Center of Russian Academy of Sciences, Fersman Str. 14, Apatity, Murmansk Region 184209, Russian Federation
³Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, POB 653, Beersheba, 84105, Israel
⁴Geomodel Resource Center, Saint Petersburg State University, Ulyanovskaya Str. 1, St. Petersburg, 198504, Russian Federation

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Ebert¹ et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13212]
¹Institut f€ur Planetologie, Westf€alische Wilhelms-Universit€at M€unster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany
Published by arrangement with John Wiley & Sons

Based on the high abundance of fine‐grained material and its dark appearance, NWA 11024 was recognized as a CM chondrite, which is also confirmed by oxygen isotope measurements. But contrary to known CM chondrites, the typical phases indicating aqueous alteration (e.g., phyllosilicates, carbonates) are missing. Using multiple analytical techniques, this study reveals the differences and similarities to known CM chondrites and will discuss the possibility that NWA 11024 is the first type 3 CM chondrite. During the investigation, two texturally apparent tochilinite–cronstedtite intergrowths were identified within two thin sections. However, the former phyllosilicates were recrystallized to Fe‐rich olivine during a heating event without changing the textural appearance. A peak temperature of 400–600 °C is estimated, which is not high enough to destroy or recrystallize calcite grains. Thus, calcites were never constituents of the mineral paragenesis. Another remarkable feature of NWA 11024 is the occurrence of unknown clot‐like inclusions (UCLIs) within fine‐grained rims, which are unique in this clarity. Their density and S concentration are significantly higher than of the surrounding fine‐grained rim and UCLIs can be seen as primary objects that were not formed by secondary alteration processes inside the rims. Similarities to chondritic and cometary interplanetary dust particles suggest an ice‐rich first‐generation planetesimal for their origin. In the earliest evolution, NWA 11024 experienced the lowest degree of aqueous alteration of all known CM chondrites and subsequently, a heating event dehydrated the sample. We suggest to classify the meteorite NWA 11024 as the first type 3 CM chondrite similar to the classification of CV3 chondrites (like Allende) that could also have lost their matrix phyllosilicates by thermal dehydration.

C. SÆTRE^1,2*, H. HELLEVANG^1,3, L. RIU⁴, H. DYPVIK^1,2, C. PILORGET⁴, F. POULET⁴, and S. C. WERNER^1,2
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13214]
¹Department of Geosciences, University of Oslo, P.O Box 1047 Blindern, N-0316 Oslo, Norway
²Centre for Earth Evolution and Dynamics, University of Oslo, P.O Box 1028 Blindern, N-0315 Oslo, Norway
³The University Centre in Svalbard (UNIS), Pb. 156, N-9171 Longyearbyen, Norway
⁴Institut d’Astrophysique Spatiale, B^atiment 121, CNRS/Universite Paris-Sud, 91405 Orsay Cedex, France
*Corresponding author. E-mail: christian.satre@geo.uio.no
Published by arrangement with John Wiley & Sons

Phyllosilicates, carbonates, zeolites, and sulfates on Mars give clues about the planet’s past environmental conditions, but little is known about the specific conditions in which these minerals formed within the crust and at the surface. The aim of the present study was to gain increased understanding on the formation of secondary phases by hydrothermal alteration of basaltic glass. The reaction processes were studied under varying conditions (temperature, pCO2, water:rock ratio, and fluid composition) with relevance to aqueous hydrothermal alteration in fully and partly saturated Martian basalt deposits. Analyses made on reaction products using X‐ray diffraction (XRD) and scanning electron microscope (SEM) were compared with near infrared spectroscopy (NIR) to establish relative detectability and spectral signatures. This study demonstrates that comparable alteration minerals (phyllosilicates, carbonates, zeolites) form from vapor condensing on mineral surfaces in unsaturated sediments and not only in fully water‐saturated sediments. In certain environments where water vapor might be present, it can alter the basaltic bedrock to a suite of authigenic phases similar to those observed on the Martian surface. For the detection of the secondary phases, XRD and SEM‐EDS were found to be superior to NIR for detecting and characterizing zeolites. The discrepancy in detectability of zeolites between NIR and XRD/SEM‐EDS might indicate that zeolites on Mars are more abundant than previously thought.

Amaya Moro-Martín
Astrophysical Journal 866, 131 Link to Article [DOI: 10.3847/1538-4357/aadf34]
Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, USA

1I/’Oumuamua is the first interstellar interloper to have been detected. Because planetesimal formation and ejection of predominantly icy objects are common by-products of the star and planet formation processes, in this study we address whether 1I/’Oumuamua could be representative of this background population of ejected objects. The purpose of the study of its origin is that it could provide information about the building blocks of planets in a size range that remains elusive to observations, helping to constrain planet formation models. We compare the mass density of interstellar objects inferred from its detection to that expected from planetesimal disks under two scenarios: circumstellar disks around single stars and wide binaries, and circumbinary disks around tight binaries. Our study makes use of a detailed study of the PanSTARRS survey volume; takes into account that the contribution from each star to the population of interstellar planetesimals depends on stellar mass, binarity, and planet presence; and explores a wide range of possible size distributions for the ejected planetesimals, based on solar system models and observations of its small-body population. We find that 1I/’Oumuamua is unlikely to be representative of a population of isotropically distributed objects, favoring the scenario that it originated from the planetesimal disk of a young nearby star whose remnants are highly anisotropic. Finally, we compare the fluxes of meteorites and micrometeorites observed on Earth to those inferred from this population of interstellar objects, concluding that it is unlikely that one of these objects is already part of the collected meteorite samples.

¹Potin, S.,¹Brissaud, O., ^1,2Beck, P., Schmitt, B., ¹Magnard, Y., ¹Correia, J.-J., ¹Rabou, P., ¹Jocou, L.
Applied Optics 57, 8279-8296 Link to Article [https://doi.org/10.1364/AO.57.008279]
¹University Grenoble Alpes, CNRS, Institut de Planétologie et d’Astrophysique de Grenoble, Grenoble, 38000, France
²Institut Universitaire de France, Paris, France

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Minako HASHIGUCHI^1* and Hiroshi NARAOKA^1,2
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13211]
¹Research Center for Planetary Trace Organic Compounds, Kyushu University, Motooka 744, Nishi-ku,Fukuoka 819-0395, Japan
²Department of Earth and Planetary Sciences, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan
*Corresponding author. E-mail: hashiguchi.minako.123@m.kyushu-u.ac.jp
Published by arrangement with John Wiley & Sons

High‐resolution mass spectrometry (HRMS) imaging by desorption electrospray ionization (DESI) coupled with Orbitrap MS using methanol (MeOH) spray was performed on a fragment of the Murchison (CM2) meteorite in this study. Homologues of C_nH_2n–1N₂⁺(n = 7–9) and C_nH_2nNO⁺ (n = 9–14) were detected on the sample surface by the imaging. A high‐performance liquid chromatography (HPLC)/HRMS analysis of MeOH extracts from the sample surface after DESI/HRMS imaging indicated that the C_nH_2n–1N₂⁺ homologues corresponds to alkylimidazole, and that a few isomers of the C_nH_2nNO⁺ homologues present in the sample. The alkylimidazoles and C_nH_2nNO⁺ homologues displayed different spatial distributions on the surface of the Murchison fragment, indicating chromatographic separation effects during aqueous alteration. Moreover, the distribution pattern of compounds is also different among homologues. This is probably also resulting from the separation of isomers by similar chromatographic effects, or different synthetic pathways. Alkylimidazoles and the C_nH_2nNO⁺ homologues are mainly distributed in the matrix region of the Murchison by mineralogical observations, which is consistent with previous reports. Altered minerals (e.g., Fe‐oxide, Fe‐sulfide, and carbonates) occurred in this region. However, no clear relationship was found between these minerals and the organic compounds detected by DESI/HRMS imaging. Although this result might be due to scale differences between the spatial resolution of DESI/HRMS imaging and the grain size in the matrix of the Murchison, our results would indicate that alkylimidazoles and the C_nH_2nNO⁺ homologues in the Murchison fragment were mainly synthesized by different processes from hydrothermal alteration on the parent body.

Tao Chen^1,2
Astrophysical Journal 866, 113 Link to Article [DOI: 10.3847/1538-4357/aae38f]
¹Leiden University, Leiden Observatory, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands
²School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Theoretical Chemistry & Biology, Royal Institute of Technology, SE-10691, Stockholm, Sweden

Photo-/ion-induced ionization and dissociation processes are commonly observed for polycyclic aromatic hydrocarbon (PAH) molecules. This work performs theoretical studies of PAHs and their fragments. Molecular dynamics simulations in combination with static quantum chemical calculations reveal that following a single hydrogen atom loss, the fragments, PAH-H, are extremely reactive. They catch a neighbor molecule within picoseconds to form a covalently bonded large molecule regardless of orientations/angles and temperatures. We calculate the infrared spectra of the covalently bonded molecules, which indicate that such species could be the carrier of unidentified infrared emission bands. It also implies that regular PAHs might be less abundant in space than what is expected.

¹Cavosie, A.J., ¹Timms, N.E., ²Ferrière, L., ³Rochette, P.
Geology 46, 891-894 Link to Article [DOI: 10.1130/G45079.1]
¹Space Science Technology Centre and The Institute for Geoscience Research (TIGeR), School of Earth and Planetary Science, Curtin University, Perth, WA 6102, Australia
²Natural History Museum, Burgring 7, Vienna, A-1010, Austria
³Aix-Marseille Univ, CNRS, INRA, IRD, Coll. France, CEREGE, Aix-en-Provence, 13545, France

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David V. BEKAERT^1*, Yves MARROCCHI¹, Alex MESHIK², Laurent REMUSAT³, and Bernard MARTY¹
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13213]
¹Centre de Recherches Petrographiques et Geochimiques, CRPG-CNRS, Universite de Lorraine, UMR 7358, 15 rue NotreDame des Pauvres, BP 20, 54501 Vandoeuvre-les-Nancy, France
²Department of Physics, Washington University, 1 Brookings Drive, Saint Louis, Missouri 63130, USA
³Institut de Mineralogie, de Physique des Materiaux et de Cosmochimie (IMPMC), UMR CNRS 7590 – Sorbonne, Universites -UPMC – IRD – Museum National d’Histoire Naturelle, 57 rue Cuvier, Case 52, 75231 Paris Cedex 5, France
Published by arrangement with John Wiley & Sons

The Paris carbonaceous chondrite represents the most pristine carbonaceous chondrite, providing a unique opportunity to investigate the composition of early solar system materials prior to the onset of significant aqueous alteration. A dual origin (namely from the inner and outer solar system) has been demonstrated for water in the Paris meteorite parent body (Piani et al. 2018). Here, we aim to evaluate the contribution of outer solar system (cometary‐like) water ice to the inner solar system water ice using Xe isotopes. We report Ar, Kr, and high‐precision Xe isotopic measurements within bulk CM 2.9 and CM 2.7 fragments, as well as Ne, Ar, Kr, and Xe isotope compositions of the insoluble organic matter (IOM). Noble gas signatures are similar to chondritic phase Q with no evidence for a cometary‐like Xe component. Small excesses in the heavy Xe isotopes relative to phase Q within bulk samples are attributed to contributions from presolar materials. CM 2.7 fragments have lower Ar/Xe relative to more pristine CM 2.9 fragments, with no systematic difference in Xe contents. We conclude that Kr and Xe were little affected by aqueous alteration, in agreement with (1) minor degrees of alteration and (2) no significant differences in the chemical signature of organic matter in CM 2.7 and CM 2.9 areas (Vinogradoff et al. 2017). Xenon contents in the IOM are larger than previously published data of Xe in chondritic IOM, in line with the Xe component in Paris being pristine and preserved from Xe loss during aqueous alteration/thermal metamorphism.