Pub Date : 2026-01-27DOI: 10.1016/j.icarus.2026.116974
Sérgio R.A. Gomes, Tibi Keizer
The passage through the mean-motion resonance between Ariel and Umbriel, two of Uranus’s largest moons, still raises several open questions. Previous studies suggest that, in order to reproduce the current orbital configuration, Ariel must have had an eccentricity of approximately ∼0.01 before the resonance encounter, which would prevent resonant capture. However, the rapid tidal circularization of Ariel’s orbit implies that some prior mechanism must have excited its eccentricity before the resonance encounter. In this work, we performed a large number of simulations using an -body integrator to assess whether the earlier mean-motion resonance between Miranda and Ariel could serve as a mechanism to increase Ariel’s eccentricity. Our results show that, due to divergent migration, resonance capture does not occur. As the satellites cross the nominal resonance, Ariel’s eccentricity is only excited to , substantially smaller than the required value. Therefore, the mean-motion resonance is not a viable mechanism for increasing Ariel’s eccentricity.
{"title":"Dynamical evolution of the Uranian satellite system III. The passage through the 7/4 MMR between Miranda and Ariel","authors":"Sérgio R.A. Gomes, Tibi Keizer","doi":"10.1016/j.icarus.2026.116974","DOIUrl":"10.1016/j.icarus.2026.116974","url":null,"abstract":"<div><div>The passage through the <span><math><mrow><mn>5</mn><mo>/</mo><mn>3</mn></mrow></math></span> mean-motion resonance between Ariel and Umbriel, two of Uranus’s largest moons, still raises several open questions. Previous studies suggest that, in order to reproduce the current orbital configuration, Ariel must have had an eccentricity of approximately ∼0.01 before the resonance encounter, which would prevent resonant capture. However, the rapid tidal circularization of Ariel’s orbit implies that some prior mechanism must have excited its eccentricity before the resonance encounter. In this work, we performed a large number of simulations using an <span><math><mi>N</mi></math></span>-body integrator to assess whether the earlier <span><math><mrow><mn>7</mn><mo>/</mo><mn>4</mn></mrow></math></span> mean-motion resonance between Miranda and Ariel could serve as a mechanism to increase Ariel’s eccentricity. Our results show that, due to divergent migration, resonance capture does not occur. As the satellites cross the nominal resonance, Ariel’s eccentricity is only excited to <span><math><mrow><mn>3</mn><mo>.</mo><mn>4</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span>, substantially smaller than the required value. Therefore, the <span><math><mrow><mn>7</mn><mo>/</mo><mn>4</mn></mrow></math></span> mean-motion resonance is not a viable mechanism for increasing Ariel’s eccentricity.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"450 ","pages":"Article 116974"},"PeriodicalIF":3.0,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-27DOI: 10.1016/j.icarus.2026.116951
M. Es-sayeh , S. Bauduin , L. Clarisse , B. Franco , M. Smith , M. Giuranna
This paper introduces a framework scheme for the detection and quantification of trace species in planetary hyperspectral datasets. The method, only used for terrestrial purposes yet, relies on a Hyperspectral Range Index (HRI) to quantify the target gas spectral signature with respect to the climatological background. The HRI is subsequently converted to a total column using an artificial feed-forward neural network built from radiative transfer (RT) model simulations. Importantly, we also provide an appropriate uncertainties characterization. The method has been applied to the Planetary Fourier Spectrometer (PFS) instrument onboard Mars Express (MEX) to retrieve HO vapor column amount. Nine Martian years of PFS/LWC (Long Wavelength Channel) measurements have been processed to acquire a data set of HO vapor total columns, analyzed, and compared to similar products from other retrieval methods. The results are comparable to those from standard retrieval methods but were achieved at a significantly reduced computational cost, demonstrating the method’s suitability for analyzing large observational datasets.
{"title":"Hyper Spectral Range Index: Detection and quantification of H2O vapor in the Martian atmosphere with PFS/MEx","authors":"M. Es-sayeh , S. Bauduin , L. Clarisse , B. Franco , M. Smith , M. Giuranna","doi":"10.1016/j.icarus.2026.116951","DOIUrl":"10.1016/j.icarus.2026.116951","url":null,"abstract":"<div><div>This paper introduces a framework scheme for the detection and quantification of trace species in planetary hyperspectral datasets. The method, only used for terrestrial purposes yet, relies on a Hyperspectral Range Index (HRI) to quantify the target gas spectral signature with respect to the climatological background. The HRI is subsequently converted to a total column using an artificial feed-forward neural network built from radiative transfer (RT) model simulations. Importantly, we also provide an appropriate uncertainties characterization. The method has been applied to the Planetary Fourier Spectrometer (PFS) instrument onboard Mars Express (MEX) to retrieve H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O vapor column amount. Nine Martian years of PFS/LWC (Long Wavelength Channel) measurements have been processed to acquire a data set of H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O vapor total columns, analyzed, and compared to similar products from other retrieval methods. The results are comparable to those from standard retrieval methods but were achieved at a significantly reduced computational cost, demonstrating the method’s suitability for analyzing large observational datasets.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116951"},"PeriodicalIF":3.0,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While sub-mm melt droplets should rapidly lose alkali elements in a vacuum at liquidus temperatures, chondrules are only modestly depleted in them (by less than one order of magnitude). The detection of sodium in olivine cores has previously suggested very high saturating partial pressures of gaseous sodium, but we show that alkalis were lost during heating and recondensed at lower temperatures, essentially in the present-day chondrule mesostases. This recondensation was accompanied by mass-dependent enrichment in light isotopes (for multi-isotope alkalis such as K and Rb), but its limited extent indicates a cooling acceleration (or “quenching”). The isotopic fractionation also constrains the ratio of the chondrule density and the cooling rate prior to the quench around kg.m.K.h suggesting densities above 10 kg/m. In a nebular context, this is achievable by radial and vertical concentrations near pressure bumps.
{"title":"Alkali recondensation into chondrules","authors":"Emmanuel Jacquet , Yves Marrocchi , Sébastien Charnoz","doi":"10.1016/j.icarus.2026.116970","DOIUrl":"10.1016/j.icarus.2026.116970","url":null,"abstract":"<div><div>While sub-mm melt droplets should rapidly lose alkali elements in a vacuum at liquidus temperatures, chondrules are only modestly depleted in them (by less than one order of magnitude). The detection of sodium in olivine cores has previously suggested very high saturating partial pressures of gaseous sodium, but we show that alkalis were lost during heating and recondensed at lower temperatures, essentially in the present-day chondrule mesostases. This recondensation was accompanied by mass-dependent enrichment in light isotopes (for multi-isotope alkalis such as K and Rb), but its limited extent indicates a cooling acceleration (or “quenching”). The isotopic fractionation also constrains the ratio of the chondrule density and the cooling rate prior to the quench around <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> kg.m<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></math></span>.K<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>.h suggesting densities above <span><math><mo>∼</mo></math></span> 10<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></math></span> kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>. In a nebular context, this is achievable by radial and vertical concentrations near pressure bumps.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116970"},"PeriodicalIF":3.0,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1016/j.icarus.2026.116963
Maximilian Vovk , Peter G. Brown , Denis Vida , Daeyoung Lee , Emma G. Harmos
<div><h3>Importance:</h3><div>Accurate estimation of meteoroid bulk density is crucial for assessing spacecraft impact hazards of sub-millimeter to millimeter-sized meteoroids, which represent the bulk of the hazard.</div></div><div><h3>Research Gap:</h3><div>Previous studies utilized manual or optimization methods for fitting numerical meteoroid ablation and fragmentation models to optical meteor observations. However, these methods struggled with reliably estimating meteoroid physical properties and the associated uncertainties due to the subjectivity of the modeling approach.</div></div><div><h3>Objective:</h3><div>We aim to develop a global and statistically robust optimization method for inferring the physical properties of individual meteors, focusing on bulk density and fragmentation behavior, using multi-instrument optical data.</div></div><div><h3>Methodology:</h3><div>We apply Dynamic Nested Sampling to fit an erosion-fragmentation model to measurements of meteor light curve and deceleration. The method was applied to 15 shower meteors observed by the Canadian Automated Meteor Observatory’s (CAMO) mirror tracking and Electron-Multiplied Charge Coupled Device (EMCCD) systems. The method yields posterior distributions and Bayesian evidences for single and double fragmentations.</div></div><div><h3>Key Findings:</h3><div>Validation against four synthetic test cases demonstrated accurate recovery of known inputs, with best-guess solutions matching true parameters. We applied this method to 9 Orionids (ORI) and 6 <span><math><mi>α</mi></math></span> Capricornids (CAP) ranging in mass from <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math></span> kg. The median bulk density was measured as <span><math><mrow><mn>15</mn><msubsup><mrow><mn>9</mn></mrow><mrow><mo>−</mo><mn>57</mn></mrow><mrow><mo>+</mo><mn>558</mn></mrow></msubsup></mrow></math></span> kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span> for Orionid meteors and <span><math><mrow><mn>33</mn><msubsup><mrow><mn>3</mn></mrow><mrow><mo>−</mo><mn>114</mn></mrow><mrow><mo>+</mo><mn>1089</mn></mrow></msubsup></mrow></math></span> kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span> for Capricornid meteors. These results are consistent with earlier studies: Orionids exhibit characteristics expected for meteoroids of cometary origin, whereas <span><math><mi>α</mi></math></span> Capricornids show systematically higher bulk densities. The CAP results show a second cluster around 1300 kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>, more inline with higher density asteroidal material, but our method achieves this using a more consistent and statistically robust estimation of uncertainties.</div></div><div><h3>Implications:</h3><
{"title":"Inferring meteoroid properties with dynamic nested sampling: A case study of orionid and capricornid shower meteors","authors":"Maximilian Vovk , Peter G. Brown , Denis Vida , Daeyoung Lee , Emma G. Harmos","doi":"10.1016/j.icarus.2026.116963","DOIUrl":"10.1016/j.icarus.2026.116963","url":null,"abstract":"<div><h3>Importance:</h3><div>Accurate estimation of meteoroid bulk density is crucial for assessing spacecraft impact hazards of sub-millimeter to millimeter-sized meteoroids, which represent the bulk of the hazard.</div></div><div><h3>Research Gap:</h3><div>Previous studies utilized manual or optimization methods for fitting numerical meteoroid ablation and fragmentation models to optical meteor observations. However, these methods struggled with reliably estimating meteoroid physical properties and the associated uncertainties due to the subjectivity of the modeling approach.</div></div><div><h3>Objective:</h3><div>We aim to develop a global and statistically robust optimization method for inferring the physical properties of individual meteors, focusing on bulk density and fragmentation behavior, using multi-instrument optical data.</div></div><div><h3>Methodology:</h3><div>We apply Dynamic Nested Sampling to fit an erosion-fragmentation model to measurements of meteor light curve and deceleration. The method was applied to 15 shower meteors observed by the Canadian Automated Meteor Observatory’s (CAMO) mirror tracking and Electron-Multiplied Charge Coupled Device (EMCCD) systems. The method yields posterior distributions and Bayesian evidences for single and double fragmentations.</div></div><div><h3>Key Findings:</h3><div>Validation against four synthetic test cases demonstrated accurate recovery of known inputs, with best-guess solutions matching true parameters. We applied this method to 9 Orionids (ORI) and 6 <span><math><mi>α</mi></math></span> Capricornids (CAP) ranging in mass from <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>5</mn></mrow></msup></mrow></math></span> kg. The median bulk density was measured as <span><math><mrow><mn>15</mn><msubsup><mrow><mn>9</mn></mrow><mrow><mo>−</mo><mn>57</mn></mrow><mrow><mo>+</mo><mn>558</mn></mrow></msubsup></mrow></math></span> kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span> for Orionid meteors and <span><math><mrow><mn>33</mn><msubsup><mrow><mn>3</mn></mrow><mrow><mo>−</mo><mn>114</mn></mrow><mrow><mo>+</mo><mn>1089</mn></mrow></msubsup></mrow></math></span> kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span> for Capricornid meteors. These results are consistent with earlier studies: Orionids exhibit characteristics expected for meteoroids of cometary origin, whereas <span><math><mi>α</mi></math></span> Capricornids show systematically higher bulk densities. The CAP results show a second cluster around 1300 kg/m<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>, more inline with higher density asteroidal material, but our method achieves this using a more consistent and statistically robust estimation of uncertainties.</div></div><div><h3>Implications:</h3><","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116963"},"PeriodicalIF":3.0,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1016/j.icarus.2026.116950
N. El-Bez-Sebastien , S. Fornasier , A. Seurat , A. Wargnier
<div><div>Primitive asteroids include C-, P-, and D-classes, known to be dark and having spectra mostly featureless. They differ in the spectral slope, which ranges from moderate values for C-types, and progressively increases in P- and D-types, the latter being the reddest. While C- and P-types are commonly observed in the asteroid main belt, D-types are commonly found further from the Sun, in the Cybele, Hilda, and Jupiter Trojans regions, and very few are reported in the main belt. This study aims at characterizing the abundance of primordial and red asteroids, belonging to the P-, D-, and Z-classes in the Mahlke et al. (2022) taxonomy, in the 2-5.2 AU region using the third data release by the Gaia mission (DR3) spectral catalog, which includes more than 60000 spectrophotometric data of asteroids. We have applied the following methodology to identify primordial asteroids in the catalog: (1) selection of objects with signal to noise ratio (SNR) greater than 20; 2) albedo value less than 12%; (3) chi-squared fit to automatically identify potential D-, Z-, and P-types using Bus-DeMeo and Mahlke taxonomy; (4) visual inspection of every spectrum to confirm the taxonomic classification.</div><div>Referring to Mahlke taxonomy, we have found 318 new D-types across the main belt, as well as 124 Z-types, which is a considerable increase from previous studies (Mahlke et al., 2022 and DeMeo et al., 2014; Humes et al., 2024b; Gartrelle et al., 2021b), and is in agreement with theoretical estimations (DeMeo et al., 2014; Vokrouhlický et al., 2016). We look for correlations among physical and orbital parameters, and we computed the spectral slope in the visible range (0.55 – <span><math><mrow><mn>0</mn><mo>.</mo><mn>81</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span>). We also have identified 265 P-types in the main belt. For the Cybele and Hilda asteroids, we characterize the taxonomic class of all the bodies with SNR higher than 20 in the Gaia catalog, for a total sample of 193 and 180 asteroids, respectively.</div><div>For D- and Z-types in the main belt, we have found a correlation between size and semimajor axis, meaning that the D-types closer to the Sun are smaller and also brighter, which could uncover their implantation processes, such as collisions or Yarkovsky effect. No families dominated by D- or Z-types have been identified so far. These red asteroids were likely formed further from the Sun and implanted during the giant planets’ migrations.</div><div>For both the Cybele and Hilda, we found a bimodal spectral slope distribution as already reported in the literature. These groups are dominated by P- and D-types. Furthermore, for both populations, despite not being the most abundant group, P-types show a larger range of diameters and include the biggest bodies, hinting at a more robust material.</div><div>We have identified 42 D- and 18 Z-asteroids having orbits with high inclination and eccentricity, and Tisserand parameter lower
原始小行星包括C-、P-和d -类，已知是暗的，光谱大多没有特征。它们的光谱斜率不同，从c型的中等值开始，P型和d型逐渐增加，后者是最红的。C型和p型通常在小行星主带中被观察到，d型通常在离太阳较远的地方被发现，在西布勒、希尔达和木星特洛伊地区，在主带中很少被报道。本研究旨在利用盖亚任务（DR3）光谱目录（包含60000多个小行星分光光度数据）第三次发布的数据，表征2-5.2 AU区域内属于P-、D-和z -类的原始和红色小行星的丰度。我们采用以下方法对星表中的原始小行星进行识别：(1)选择信噪比大于20的天体；2)反照率小于12%；(3)利用Bus-DeMeo和Mahlke分类法自动识别潜在的D-、Z-和p型；(4)目视检查各光谱以确定分类学分类。参考Mahlke分类学，我们在主带发现了318个新的d型和124个新的z型，这比以往的研究（Mahlke et al.， 2022和DeMeo et al., 2014; Humes et al., 2024b; Gartrelle et al., 2021b）有很大的增加，与理论估计一致（DeMeo et al., 2014; Vokrouhlický et al., 2016）。我们寻找物理参数和轨道参数之间的相关性，并计算了可见光范围（0.55 ~ 0.81μm）内的光谱斜率。在主带中还鉴定出265个p型。对于Cybele和Hilda小行星，我们分别对总共193颗和180颗小行星的Gaia目录中信噪比大于20的所有天体进行了分类分类。对于主带中的D型和z型，我们发现了尺寸与半长轴之间的相关性，这意味着离太阳更近的D型更小，也更亮，这可能揭示了它们的植入过程，如碰撞或亚尔科夫斯基效应。目前尚未发现以D型或z型为主的家族。这些红色小行星很可能在离太阳更远的地方形成，并在巨行星迁移过程中被植入。对于Cybele和Hilda，我们发现了文献中已经报道的双峰光谱斜率分布。这些群体以P型和d型为主。此外，对于这两个种群来说，尽管不是最丰富的群体，p型显示出更大的直径范围，包括最大的物体，暗示着更坚固的物质。我们已经确定了42颗D型和18颗z型小行星，它们的轨道具有高倾角和离心率，Tisserand参数小于3，它们可能是彗星起源，主要分布在主带，Cybele，主要在Hilda。我们还将其平均D型和z型光谱与火卫一和火卫二这两个火星卫星的光谱进行了比较。火卫一的光谱更接近z型，而火卫一的红色单元更接近d型，这证实了火星卫星可能是被捕获的小行星的可能性。
{"title":"Primitive asteroids in the main belt, Cybele, and Hilda populations from Gaia DR3","authors":"N. El-Bez-Sebastien , S. Fornasier , A. Seurat , A. Wargnier","doi":"10.1016/j.icarus.2026.116950","DOIUrl":"10.1016/j.icarus.2026.116950","url":null,"abstract":"<div><div>Primitive asteroids include C-, P-, and D-classes, known to be dark and having spectra mostly featureless. They differ in the spectral slope, which ranges from moderate values for C-types, and progressively increases in P- and D-types, the latter being the reddest. While C- and P-types are commonly observed in the asteroid main belt, D-types are commonly found further from the Sun, in the Cybele, Hilda, and Jupiter Trojans regions, and very few are reported in the main belt. This study aims at characterizing the abundance of primordial and red asteroids, belonging to the P-, D-, and Z-classes in the Mahlke et al. (2022) taxonomy, in the 2-5.2 AU region using the third data release by the Gaia mission (DR3) spectral catalog, which includes more than 60000 spectrophotometric data of asteroids. We have applied the following methodology to identify primordial asteroids in the catalog: (1) selection of objects with signal to noise ratio (SNR) greater than 20; 2) albedo value less than 12%; (3) chi-squared fit to automatically identify potential D-, Z-, and P-types using Bus-DeMeo and Mahlke taxonomy; (4) visual inspection of every spectrum to confirm the taxonomic classification.</div><div>Referring to Mahlke taxonomy, we have found 318 new D-types across the main belt, as well as 124 Z-types, which is a considerable increase from previous studies (Mahlke et al., 2022 and DeMeo et al., 2014; Humes et al., 2024b; Gartrelle et al., 2021b), and is in agreement with theoretical estimations (DeMeo et al., 2014; Vokrouhlický et al., 2016). We look for correlations among physical and orbital parameters, and we computed the spectral slope in the visible range (0.55 – <span><math><mrow><mn>0</mn><mo>.</mo><mn>81</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span>). We also have identified 265 P-types in the main belt. For the Cybele and Hilda asteroids, we characterize the taxonomic class of all the bodies with SNR higher than 20 in the Gaia catalog, for a total sample of 193 and 180 asteroids, respectively.</div><div>For D- and Z-types in the main belt, we have found a correlation between size and semimajor axis, meaning that the D-types closer to the Sun are smaller and also brighter, which could uncover their implantation processes, such as collisions or Yarkovsky effect. No families dominated by D- or Z-types have been identified so far. These red asteroids were likely formed further from the Sun and implanted during the giant planets’ migrations.</div><div>For both the Cybele and Hilda, we found a bimodal spectral slope distribution as already reported in the literature. These groups are dominated by P- and D-types. Furthermore, for both populations, despite not being the most abundant group, P-types show a larger range of diameters and include the biggest bodies, hinting at a more robust material.</div><div>We have identified 42 D- and 18 Z-asteroids having orbits with high inclination and eccentricity, and Tisserand parameter lower ","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116950"},"PeriodicalIF":3.0,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.icarus.2026.116971
D.D. Patel , G.R. Osinski , S.M. Patel
The youngest era in the lunar geological timescale, the Copernican period, is estimated to have commenced approximately 1.1 billion years ago and is named after the prominent 95 km-diameter Copernicus crater. Copernican craters represent the youngest and best-preserved impact craters on the Moon. This study presents the first high-resolution geological and morphological map of the ∼48 km diameter Copernican-age Rutherfurd crater, produced through the integration of optical, radar, and hyperspectral datasets. Observations reveal significant asymmetry in the crater's structure, particularly in terms of slumping, terracing, and rim preservation, which we interpret as being due to the effects of pre-existing topography. Spectral analysis indicates the dominance of high-calcium pyroxene (HCP) within the central peak, rim, and isolated mounds, suggesting excavation of a buried HCP-rich plagioclase layer. Crater Size-Frequency Distribution (CSFD) analysis of the continuous ejecta blanket yields an age of ∼1-1.1 Ga, confirming Rutherfurd as the youngest crater in the Clavius crater arching chain. In contrast, CSFDs from the impact melt ponds yield anomalously younger apparent ages (∼200–510 Myr), likely reflecting statistical uncertainties arising from their limited surface area and the paucity of large craters, rather than true differences in formation age. Distinct asymmetries in ejecta distribution and secondary crater patterns are interpreted to reflect the oblique nature of the impact and interactions with local topographic variations. Ejecta morphology and secondary crater orientations suggest an oblique impact from the southeast to northwest at an angle of ∼20–30°. This study not only refines our understanding of Rutherfurd’s formation and evolution but also highlights its significance as a target for future lunar exploration, particularly due to its exposure of deeper crustal materials and proximity to regions with potential hydration signatures.
{"title":"An integrated study of Rutherfurd crater: Composition, morphology, and chronology","authors":"D.D. Patel , G.R. Osinski , S.M. Patel","doi":"10.1016/j.icarus.2026.116971","DOIUrl":"10.1016/j.icarus.2026.116971","url":null,"abstract":"<div><div>The youngest era in the lunar geological timescale, the Copernican period, is estimated to have commenced approximately 1.1 billion years ago and is named after the prominent 95 km-diameter Copernicus crater. Copernican craters represent the youngest and best-preserved impact craters on the Moon. This study presents the first high-resolution geological and morphological map of the ∼48 km diameter Copernican-age Rutherfurd crater, produced through the integration of optical, radar, and hyperspectral datasets. Observations reveal significant asymmetry in the crater's structure, particularly in terms of slumping, terracing, and rim preservation, which we interpret as being due to the effects of pre-existing topography. Spectral analysis indicates the dominance of high-calcium pyroxene (HCP) within the central peak, rim, and isolated mounds, suggesting excavation of a buried HCP-rich plagioclase layer. Crater Size-Frequency Distribution (CSFD) analysis of the continuous ejecta blanket yields an age of ∼1-1.1 Ga, confirming Rutherfurd as the youngest crater in the Clavius crater arching chain. In contrast, CSFDs from the impact melt ponds yield anomalously younger apparent ages (∼200–510 Myr), likely reflecting statistical uncertainties arising from their limited surface area and the paucity of large craters, rather than true differences in formation age. Distinct asymmetries in ejecta distribution and secondary crater patterns are interpreted to reflect the oblique nature of the impact and interactions with local topographic variations. Ejecta morphology and secondary crater orientations suggest an oblique impact from the southeast to northwest at an angle of ∼20–30°. This study not only refines our understanding of Rutherfurd’s formation and evolution but also highlights its significance as a target for future lunar exploration, particularly due to its exposure of deeper crustal materials and proximity to regions with potential hydration signatures.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116971"},"PeriodicalIF":3.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.icarus.2026.116961
Kelly E. Miller , Mohit Melwani Daswani , Christophe Sotin , Charles S. Cockell , Catherine Neish , Michael J. Malaska , Kendra K. Farnsworth , Conor A. Nixon , Krista M. Soderlund , Peter M. Higgins , Antonin Affholder , Rosaly M.C. Lopes
As an organic-rich world with a subsurface ocean, Titan is an object of great astrobiological interest. However, geological signs of surface-subsurface exchange are limited, and Titan’s thick icy crust may significantly impede delivery of organic-rich surface materials to the subsurface ocean. Heating of accreted complex organic material in Titan’s interior may provide an additional source of organic molecules to serve as building blocks for life and/or chemical energy sources for ocean habitability. Here, we investigate the composition of Titan’s subsurface ocean with a focus on organic materials derived from the rocky interior. We develop organic-rich compositional models, and consider what effects heating of these organics may have on the total noble gas signature in Titan’s atmosphere. We compare this signature to existing constraints to provide a consistent framework for the abundance of organic material derived from the interior. Present day constraints generally allow contributions of both noble gas ices and Phase Q noble gases from heating of abundant organic material, but the Xe signature may be inconsistent with ices. We combine this compositional framework with a thermal profile for Titan’s interior that includes the thermophysical properties of organic material, and perform thermodynamic calculations for extraction of volatiles and formation of the hydrosphere. Our results suggest that formation of Titan’s massive hydrosphere requires a large initial ice mass, including a minimum ice/dust mass ratio of 1.4 for anhydrous cometary dust. Finally, we consider the composition and abundance of organic material produced by such processes and them to dissolved organic carbon in terrestrial oceans. We find that Titan’s accreted complex organic material may be a significant contributor to organic material in the subsurface ocean, producing organic abundances that are comparable to terrestrial oceans.
{"title":"Titan’s refractory core evolution: Implications for organics in its subsurface ocean","authors":"Kelly E. Miller , Mohit Melwani Daswani , Christophe Sotin , Charles S. Cockell , Catherine Neish , Michael J. Malaska , Kendra K. Farnsworth , Conor A. Nixon , Krista M. Soderlund , Peter M. Higgins , Antonin Affholder , Rosaly M.C. Lopes","doi":"10.1016/j.icarus.2026.116961","DOIUrl":"10.1016/j.icarus.2026.116961","url":null,"abstract":"<div><div>As an organic-rich world with a subsurface ocean, Titan is an object of great astrobiological interest. However, geological signs of surface-subsurface exchange are limited, and Titan’s thick icy crust may significantly impede delivery of organic-rich surface materials to the subsurface ocean. Heating of accreted complex organic material in Titan’s interior may provide an additional source of organic molecules to serve as building blocks for life and/or chemical energy sources for ocean habitability. Here, we investigate the composition of Titan’s subsurface ocean with a focus on organic materials derived from the rocky interior. We develop organic-rich compositional models, and consider what effects heating of these organics may have on the total noble gas signature in Titan’s atmosphere. We compare this signature to existing constraints to provide a consistent framework for the abundance of organic material derived from the interior. Present day constraints generally allow contributions of both noble gas ices and Phase Q noble gases from heating of abundant organic material, but the Xe signature may be inconsistent with ices. We combine this compositional framework with a thermal profile for Titan’s interior that includes the thermophysical properties of organic material, and perform thermodynamic calculations for extraction of volatiles and formation of the hydrosphere. Our results suggest that formation of Titan’s massive hydrosphere requires a large initial ice mass, including a minimum ice/dust mass ratio of 1.4 for anhydrous cometary dust. Finally, we consider the composition and abundance of organic material produced by such processes and them to dissolved organic carbon in terrestrial oceans. We find that Titan’s accreted complex organic material may be a significant contributor to organic material in the subsurface ocean, producing organic abundances that are comparable to terrestrial oceans.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116961"},"PeriodicalIF":3.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.icarus.2026.116952
Edward A. Cloutis , Devin L. Schrader , Daniel M. Applin , Tomoki Nakamura , Timothy D. Glotch , Takahiro Hiroi , Moe Matsuoka , Michael E. Zolensky , Joshua P. Emery , Kristi M. Peters
Four carbonaceous chondrite (CC) meteorites – MET 00432, Tagish Lake, Tarda, and WIS 91600 - have been proposed to be members of a CC grouplet, hereafter termed the Carbonaceous Tagish Lake Grouplet (CTG). We investigated their possible affinities via a spectral reflectance-focused study of them, as chips and variously sized powders. We also considered possible spectrum-altering effects of space weathering and composition of the organic component on such red-sloped spectra. Ultraviolet-region spectra (200-400 nm) exhibit absorption features attributable to unspecific Fe2+-O and/or Fe3+-O charge transfers, possibly due to Fe-rich phyllosilicates. Both albedo and spectral slope vary as a function of grain size. The 0.35-2.50 μm interval is characterized by dark, variably red-sloped spectra with low albedos in the visible region (<6% reflectance at 0.550 μm). Spectral slopes are redder for powders than slabs or chips. CTG spectra also exhibit shallow (<4% deep) absorption bands attributable to known components, such as magnetite and phyllosilicates, particularly in the 1 μm region. Spectral analysis of an extensive suite of phyllosilicate+opaque mixtures suggests that only a subset of CTG opaque components can cause darkening and overall red spectral slopes, in particular low H/C ratio carbonaceous compounds. Other opaque components, such as iron sulfides, magnetite and other carbonaceous materials, some of which are red-sloped when pure, cause spectral bluing or only slight spectral reddening. Albedo and spectral slopes and shapes are affected by physical properties, such as grain size, as well as the types, compositions, abundances, dispersion, and grain sizes of opaque components. At longer wavelengths (to 14 μm), CTG spectra exhibit a number of absorption features that can be related to their silicate, carbonate, and organic components. A prominent absorption feature is present in the 2.7-3.1 μm region attributable to phyllosilicates ± H2O, some of which is likely attributable to terrestrial alteration. Petrological, mineralogical, and isotopic information provide support for these meteorites having strong affinities to each other and comprising a grouplet. Additional CTG meteorites may lurk among the many tens of CCs that have been incompletely characterized.
{"title":"Reflectance spectroscopy (200-4200 nm) of the red-sloped C2 carbonaceous chondrites MET 00432, Tagish Lake, Tarda, and WIS 91600 (“CT” grouplet)","authors":"Edward A. Cloutis , Devin L. Schrader , Daniel M. Applin , Tomoki Nakamura , Timothy D. Glotch , Takahiro Hiroi , Moe Matsuoka , Michael E. Zolensky , Joshua P. Emery , Kristi M. Peters","doi":"10.1016/j.icarus.2026.116952","DOIUrl":"10.1016/j.icarus.2026.116952","url":null,"abstract":"<div><div>Four carbonaceous chondrite (CC) meteorites – MET 00432, Tagish Lake, Tarda, and WIS 91600 - have been proposed to be members of a CC grouplet, hereafter termed the Carbonaceous Tagish Lake Grouplet (CTG). We investigated their possible affinities via a spectral reflectance-focused study of them, as chips and variously sized powders. We also considered possible spectrum-altering effects of space weathering and composition of the organic component on such red-sloped spectra. Ultraviolet-region spectra (200-400 nm) exhibit absorption features attributable to unspecific Fe<sup>2+</sup>-O and/or Fe<sup>3+</sup>-O charge transfers, possibly due to Fe-rich phyllosilicates. Both albedo and spectral slope vary as a function of grain size. The 0.35-2.50 μm interval is characterized by dark, variably red-sloped spectra with low albedos in the visible region (<6% reflectance at 0.550 μm). Spectral slopes are redder for powders than slabs or chips. CTG spectra also exhibit shallow (<4% deep) absorption bands attributable to known components, such as magnetite and phyllosilicates, particularly in the 1 μm region. Spectral analysis of an extensive suite of phyllosilicate+opaque mixtures suggests that only a subset of CTG opaque components can cause darkening and overall red spectral slopes, in particular low H/C ratio carbonaceous compounds. Other opaque components, such as iron sulfides, magnetite and other carbonaceous materials, some of which are red-sloped when pure, cause spectral bluing or only slight spectral reddening. Albedo and spectral slopes and shapes are affected by physical properties, such as grain size, as well as the types, compositions, abundances, dispersion, and grain sizes of opaque components. At longer wavelengths (to 14 μm), CTG spectra exhibit a number of absorption features that can be related to their silicate, carbonate, and organic components. A prominent absorption feature is present in the 2.7-3.1 μm region attributable to phyllosilicates ± H<sub>2</sub>O, some of which is likely attributable to terrestrial alteration. Petrological, mineralogical, and isotopic information provide support for these meteorites having strong affinities to each other and comprising a grouplet. Additional CTG meteorites may lurk among the many tens of CCs that have been incompletely characterized.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116952"},"PeriodicalIF":3.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.icarus.2026.116969
Xiaoying Liu , Chi Zhang , Zongyu Yue, Lixin Gu, Jing Li, Heng-Ci Tian, Sen Hu, Yangting Lin
Meteorite impact is a key process on the Moon, having profoundly reshaped the lunar surface, modified the physical properties of lunar regolith, and transported water and other volatiles on the surface. However, the temperature-pressure conditions of impact-induced plumes and their duration were poorly constrained. Here, we report the first discovery of immiscibility a FeNi-P-S bead from Chang'e-5 lunar soils, which consists of abundant spherules of metallic FeNi and sulfide both evenly dispersed in phosphide-rich matrix. The observed texture and compositions are consistent with quenching of an FeNi-P-S melt droplet, generated during an iron meteorite impact. The initial droplet was homogeneous and formed at >1800 °C and > 11–16 GPa within the impact plume, based on high-pressure experiments of the Fe-P-S system. As the plume expanding, FeNi spherules emerged from the droplet at 11–16 GPa, estimated by P partitioning between the metal and P-S-rich melt. Subsequent separation of the P-S-rich melt into immiscible sulfide-rich spherules and phosphide-rich mesostasis occurred at 1 bar–3 GPa and 1000–1100 °C. The duration of the pressure declining from >11–16 GPa to 1 bar–3 GPa was estimated to be 0.5–1 s, combining the impact plume expansion model with the cooling rate inferred from the metallic bead. This study demonstrates that high-pressure conditions of impact plumes can be retained for second timescales, which is critical for chemical reactions and water and other volatile migration on the Moon's surface.
{"title":"Duration of high temperature-pressure conditions in impact-induced plumes on the Moon","authors":"Xiaoying Liu , Chi Zhang , Zongyu Yue, Lixin Gu, Jing Li, Heng-Ci Tian, Sen Hu, Yangting Lin","doi":"10.1016/j.icarus.2026.116969","DOIUrl":"10.1016/j.icarus.2026.116969","url":null,"abstract":"<div><div>Meteorite impact is a key process on the Moon, having profoundly reshaped the lunar surface, modified the physical properties of lunar regolith, and transported water and other volatiles on the surface. However, the temperature-pressure conditions of impact-induced plumes and their duration were poorly constrained. Here, we report the first discovery of immiscibility a FeNi-P-S bead from Chang'e-5 lunar soils, which consists of abundant spherules of metallic FeNi and sulfide both evenly dispersed in phosphide-rich matrix. The observed texture and compositions are consistent with quenching of an FeNi-P-S melt droplet, generated during an iron meteorite impact. The initial droplet was homogeneous and formed at >1800 °C and > 11–16 GPa within the impact plume, based on high-pressure experiments of the Fe-P-S system. As the plume expanding, FeNi spherules emerged from the droplet at 11–16 GPa, estimated by P partitioning between the metal and P-S-rich melt. Subsequent separation of the P-S-rich melt into immiscible sulfide-rich spherules and phosphide-rich mesostasis occurred at 1 bar–3 GPa and 1000–1100 °C. The duration of the pressure declining from >11–16 GPa to 1 bar–3 GPa was estimated to be 0.5–1 s, combining the impact plume expansion model with the cooling rate inferred from the metallic bead. This study demonstrates that high-pressure conditions of impact plumes can be retained for second timescales, which is critical for chemical reactions and water and other volatile migration on the Moon's surface.</div></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"449 ","pages":"Article 116969"},"PeriodicalIF":3.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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