¹Te Jiang et al. (>10)
Astronomy & Astrophysics, 705, A223
Open Access Link to Article [DOI: 10.1051/0004-6361/202555761]
¹School of Earth Sciences and Hubei Key Laboratory of Planetary Geology and Space Explorations, China University of Geosciences, Wuhan, China

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¹M. Mahlke, ²M. Marsset, ³M. Devogèle, ⁴D. Baklouti, ⁵P. Beck, ⁵L. Bonal, ⁴R. Brunetto, ⁴C. Lantz, ⁶P. Tanga
Astronomy & Astrophysics, 705, A121
Open Access Link to Article [DOI: 10.1051/0004-6361/202555785]
¹Université Marie et Louis Pasteur, CNRS, Institut UTINAM (UMR 6213), équipe Astro, 25000 Besançon, France
²European Southern Observatory, Alonso de Córdova 3107, 1900 Casilla Vitacura, Santiago, Chile
³European Space Agency, NEO Coordination Centre, Largo Galileo Galilei, 1, 00044 Frascati (RM), Italy
⁴Institut d’Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France
⁵Institut de Planétologie et d’Astrophysique de Grenoble, Université Grenoble Alpes, 38000 Grenoble, France
⁶Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Matthew Belyakov, ²Ian Wong, ³Carey M. Lisse, ⁴M. Ryleigh Davis, ⁵Bryce T. Bolin, ¹Audrey Martin, ⁶Klaus M. Pontoppidan, ¹Geoffrey A. Blake, ²Christine Chen, ¹Michael E. Brown
The Astrophysical Journal Letters, 1009, L41
Open Access Link to Article [DOI: 10.3847/2041-8213/aea84e]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
²Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
³Johns Hopkins University Applied Physics Laboratory, Planetary Exploration Group, Space Department, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
⁴Department of Astronomy & Astrophysics, University of California San Diego, La Jolla, CA 92093, USA
⁵Eureka Scientific, Oakland, CA 94602, USA
⁶Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA

We present the first spectroscopic mineralogical analysis of the dust coma of an interstellar object (ISO) from JWST mid-infrared spectroscopy of 3I/ATLAS (3I). 3I exhibits a strong 9–11 μm emissivity feature due to Si–O vibrational stretching modes that is commonly seen in asteroids, comets, disks, and the interstellar medium. Characterization of this 10 μm emissivity maximum reveals that 3I’s dust composition is dominated by amorphous silicates, and that 3I is unlike solar system comets, which show significant crystalline silicate dust. Instead, 3I’s dust composition is more similar to circumstellar transition disks and the interstellar medium. We suggest 3I may have formed in a distant part of its home system out of interstellar medium–like material, without substantial incorporation of silicates condensed near its host star, unlike the mixing scenarios commonly suggested for the solar system. Alternatively, 3I’s original crystalline silicates may have been amorphized during its Gyr-long journey, although we find this alternative less likely due to 3I’s mass-loss rate and distinct 10 μm feature as compared to observed solar system comets.

^1,2Shu Wang, ^1,3Zhuochao Huang, ^1,2,4Xiaodian Chen, ^4,5,1Junming He, ^1,2Haomiao Huang
The Astrophysical Journal, 1009, 58
Open Access Link to Article [DOI: 10.3847/1538-4357/ae909c]
¹CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
²School of Astronomy and Space Science, University of the Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
³School of Space and Earth Sciences, Beihang University, Beijing 102206, People’s Republic of China
⁴Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, People’s Republic of China
⁵School of Physics and Astronomy, Beijing Normal University, Beijing 100875, People’s Republic of China

Extreme debris disks provide time-domain probes of rocky planet assembly after giant impacts. We compare Spitzer and JWST spectra of the warm debris disk around HD 15407A, obtained 14.95 yr apart. Across 6–25 μm, the stellar-subtracted mid-infrared excess declined by 14.0% ± 1.2%, while the mineral fingerprint is nearly unchanged. Within the adopted common reduced mineral basis, Mg-rich pyroxene dominates the normalized fitted mineral weights at about 65%, while silica and forsterite contribute about 22%–23% and 12%–13%, respectively. In both epochs, about 93%–94% of the fitted mineral weight is carried by 5.0 μm grains. The fitted optically thin surface-component amplitude drops by 32%, consistent with reduced mineral-emitting flux from the disk surface rather than the appearance of a new dust composition. A simple collisional-cascade guide fitted to the IRAS-to-JWST multiepoch ratios gives t_c = 87⁺¹⁷₋₁₂ yr, for which the Spitzer-normalized dust-excess ratio reaches 0.5 after one t_c. HD 15407A is consistent with an evolved postimpact reservoir with limited recent supply of very small grains: its rocky mineral fingerprint has remained stable since at least 2008, while its warm mineral-emitting flux is gradually fading over several hundred years.

¹Y. Fu, ¹H. Z. Wang, ¹J. Zhang, ¹Q. Q. Shi, ¹R. L. Guo, ¹A. M. Tian, ²C. Yue
The Astrophysical Journal, 1008, 141
Open Access Link to Article [DOI: 10.3847/1538-4357/ae9098]
¹Shandong Key Laboratory of Space Environment and Exploration Technology, School of Space Science and Technology, Institute of Space Sciences, Shandong University, Key Laboratory of Eco-Environment and Population Health of Xizang Autonomous Region, Weihai, Shandong, 264209, People’s Republic of China
²School of Earth and Space Sciences, Institute of Space Physics and Applied Technology, Peking University, Beijing, People’s Republic of China

Solar wind ion irradiation and micrometeoroid impacts are two primary agents of lunar space weathering, but their relative contributions remain unclear. This study provides new constraints by analyzing optical maturity (OMAT) asymmetries of crater walls in the lunar polar regions (latitude > 50°). Using OMAT derived from Kaguya Spectral Profiler observations, we analyze the equator facing–pole facing (EF–PF) and east–west (E–W) space weathering asymmetries of polar crater walls. After excluding craters significantly affected by geological processes, such as crater degradation, impact ejecta mixing, and impact excavation, the EF–PF asymmetry increases toward polar regions at latitudes above 50°, whereas previous studies reported the opposite trend at latitudes below 50°, indicating a latitudinal trend reversal occurring around 50°. The E-W asymmetry is similar to that observed at low latitudes. Simulations based on real crater morphology show that solar wind alone (even with the shielding effect of the Earth’s magnetosphere) cannot explain the latitude of this trend reversal, which may be due to the increasing importance of micrometeoroid flux at high latitudes. However, by including micrometeoroid impacts, which have a more isotropic flux, our models successfully reproduce the observations. The simulations suggest that micrometeoroid impacts should contribute at least 70% as much as the solar wind to space weathering in the lunar equatorial region. This work demonstrates that micrometeoroid impacts are a significant process in lunar space weathering comparable in importance to the solar wind.

¹Sota Arakawa, ^2,3Takayuki Ushikubo, ⁴Ryosuke T. Tominaga
The Astrophysical Journal, 1008, 161
Open Access Link to Article [DOI: 10.3847/1538-4357/ae93a1]
¹Center for Mathematical Science and Advanced Technology, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001, Japan
²Kochi Institute for Core Sample Research, EMS, Japan Agency for Marine-Earth Science and Technology, 200 Monobe-otsu, Nankoku, Kochi, 783-8502, Japan
³Marine Core Research Institute, Kochi University, 200 Monobe-otsu, Nankoku, Kochi, 783-8502, Japan
⁴Department of Earth and Planetary Sciences, Institute of Science Tokyo, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan

Chondrules are thought to have formed during transient flash-heating events in dust-enriched regions of the solar protoplanetary disk. Although laboratory studies have characterized the oxygen isotopic compositions of chondritic materials, quantitative interpretations based on simulations of disk formation and evolution remain limited. Here, we perform one-dimensional simulations of disk formation and evolution by solving a diffusion–advection equation with mass infall from the parental cloud core. We compute the temporal evolution of oxygen isotopic compositions using an experimentally derived isotope-exchange model. We examine how the oxygen isotopic signatures of the disk depend on the radial distribution of infalling material and the composition of the parental cloud core. We find that the oxygen isotopic compositions of carbonaceous-chondrite chondrules can be reproduced if either (i) the radial extent of mass infall onto the disk is moderate (∼10 au), or (ii) it is large (>10 au) and the parental cloud core was ice-depleted and/or experienced weaker CO self-shielding than is commonly assumed. In contrast, if ordinary-chondrite chondrules formed inside the snow line under background temperatures of ≲500 K, their oxygen isotopic compositions may be difficult to explain within the present disk-evolution model, because oxygen isotopic exchange between silicates and vapor species proceeds efficiently only in the inner disk at T ≳ 500–600 K.

¹Jiaqi Kong, ¹Haijun Cao, ¹Xuejun Lu, ¹Jian Chen, ¹Ziyi Jia, ¹Zongcheng Ling
The Astrophysical Journal, 1008, 38
Open Access Link to Article [DOI: 10.3847/1538-4357/ae9542]
¹Shandong Key Laboratory of Space Environment and Exploration Technology, Institute of Space Sciences, School of Space Science and Technology, Shandong University, Weihai, Shandong 264209, People’s Republic of China

Mg# (molar Mg/(Mg+Fe)) is a critical geochemical indicator for quantifying the evolution of the lunar crust, providing essential insights into regional compositional variability, crustal differentiation processes, and the crystallization history of the early lunar magma ocean (LMO). The Lorentz and Coulomb-Sarton (LCS) basins on the lunar farside exhibit significant magnesium anomalies in global surface chemistry maps that challenge traditional models of lunar crustal development. By integrating multisource lunar remote sensing data, we applied spectral parameter techniques and the Hapke radiative transfer model to assess the mineralogical characteristics of the LCS region and produce an updated geological map. The results reveal that the LCS region is predominantly dominated by plagioclase (>72.1 wt%), primarily in the form of ferroan anorthosites (FANs) with low-Mg# (<70) lithologies. Regions of elevated Mg# (>70) are concentrated in the western and northern portions of the Coulomb-Sarton basin and the central ring of the Lorentz basin. These localized anomalies correspond to Mg-rich lithologies that are interpreted as magnesian anorthosites derived from deeper crustal levels and subsequently exposed by impact excavation. This spatial pattern is consistent with a vertically stratified crustal structure, in which the upper crust consists predominantly of primordial FANs formed during the early LMO solidification. While deeper crustal materials may be related to magmatic intrusion from mantle-derived melts, they are intermittently exposed by large impact events and basin-scale modification processes. These findings provide new insights into the mineralogy and composition of the lunar farside highlands and constraints on the complex crustal evolution of the LCS region.

^1,2Bo-Lun Huang, ³Zhen-Zhao Tao, ^1,2Tong-Jie Zhang
The Astrophysical Journal, 1006, 9
Open Access Link to Article [DOI: 10.3847/1538-4357/ae742c]
¹Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, People’s Republic of China
²School of Physics and Astronomy, Beijing Normal University, Beijing 100875, People’s Republic of China
³College of Computer and Information Engineering, Dezhou University, Dezhou 253023, People’s Republic of China

We present a meteorite-calibrated Bayesian framework for searching archival abundance records for chemical technosignatures—operationally, compositional patterns better explained by an idealized “processed” template (endmember) than by the empirical distribution of natural rocks. We fit a multimodal natural-composition reference using 3493 whole-rock meteorite analyses, and for each of 697 star–paper abundance sets—spanning at least 397 distinct objects once Gaia-designated repeats are consolidated—we compare the Bayesian evidence for (i) natural material and (ii) a mixture of natural material with a fixed siderophile-enriched template, parameterized by a Ca-normalized mixing fraction α. Strong support for the processed template is uncommon: in the atmospheric compilation (atm) 8/697 records have BF > 10 (4/697 have BF > 100), and in the diffusion-adjusted steady-state subset (acc_ss; 148 records spanning at least 94 objects) 6/148 have BF > 10. We report the highest-evidence candidate records and infer the fraction of records detectably favoring the mixture model, with posterior medians π̃ = 0.011 (atm) and π̃ = 0.041 (acc_ss). We calibrate the analysis with end-to-end injection–recovery experiments matched to each record’s coverage and censoring. The calibration shows that discrimination is driven mainly by chemical information, typically requires ≳5 detected elements for decisive support, and—for the siderophile template—is strongest for exact, five-element panels that include Fe, Mg, Cr, and Ti together with Ni, Si, or Na. These results constrain the detectable incidence of the tested processed-composition class in current data and set observational requirements for future multielement surveys and expanded template families.

^1,2Patrick Cordier et al. (>10)
The Astrophysical Journal, 1005, 87
Open Access Link to Article [DOI: 10.3847/1538-4357/ae71bd]
¹Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207—UMET—Unité Matériaux et Transformations, F-59000 Lille, France
²Institut Universitaire de France, 1 rue Descartes, F-75005 Paris, France

Olivine is one of the most abundant silicate minerals in cosmic environments, occurring largely in amorphous form in the interstellar medium before crystallizing within protoplanetary disks. The kinetics and mechanisms governing this transition are central to understanding the thermal and chemical evolution of silicate dust. To investigate these processes at high spatial and structural resolution, we conducted an in situ transmission electron microscopy study on amorphous olivine thin films produced by pulsed laser deposition. Structural and chemical evolution during heating was monitored using selected-area electron diffraction, pair distribution function analysis, automated crystal orientation mapping, electron energy-loss spectroscopy, and aberration-corrected high-resolution transmission electron microscopy. The amorphous material begins to chemically reorganize at ∼400 °C, where Fe²⁺ is oxidized to Fe³⁺ and nanoscale crystallites—presumably hematite—form within the glassy matrix. These crystallites appear to act as nucleation sites that promote subsequent olivine crystallization. Full crystallization occurs near 800 °C, yielding grains 50–150 nm in size. These observations provide direct nanoscale evidence for iron-assisted nucleation in amorphous olivine and offer constraints on the temperatures and pathways governing the crystallization of interstellar and protoplanetary silicate dust.

^1,2I. Psaradaki et al. (>10)
The Astrophysical Journal, 1005, 53
Open Access Link to Article [DOI: 10.3847/1538-4357/ae78dd]
¹MIT Kavli Institute for Astrophysics and Space Research, 70 Vassar Street, Cambridge, MA 02139, USA
²European Space Agency (ESA), European Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands

We present results on X-ray absorption and the dust grain chemistry in the diffuse interstellar medium, based on a new Cycle 25 Chandra High Energy Transmission Grating Spectrometer (HETGS) observational campaign targeting the black hole transient GX 339–4. The X-ray source offers an optimal combination of moderate hydrogen column density and high X-ray flux, enabling the first detailed simultaneous fitting of the photoabsorption edges of Fe, O, Si, and Mg, which are key elemental constituents of interstellar dust. We perform a joint spectral analysis of Chandra/HETGS data and archival observations from the Reflection Grating Spectrometer on board XMM-Newton. We find that the dust grain chemical composition along this diffuse Galactic line of sight is best described by the silicate Mg-rich amorphous pyroxene (Mg_0.75Fe_0.25SiO₃) and metallic iron. We also discuss the elemental abundances and depletions of Fe, O, Si, and Mg, and the presence of absorption features in the X-ray spectrum of this source associated with highly ionized plasma.