Icarus最新文献

{"title":"Unambiguous detection of mesospheric CO2 clouds on Mars using 2.7 μm absorption band from the ACS/TGO solar occultations","authors":"M. Luginin ,&nbsp;A. Trokhimovskiy ,&nbsp;A. Fedorova ,&nbsp;D. Belyaev ,&nbsp;N. Ignatiev ,&nbsp;O. Korablev ,&nbsp;F. Montmessin ,&nbsp;A. Grigoriev","doi":"10.1016/j.icarus.2024.116271","DOIUrl":"10.1016/j.icarus.2024.116271","url":null,"abstract":"<div><p>Mesospheric CO₂ clouds are one of two types of carbon dioxide clouds known on Mars. We present observations of mesospheric CO₂ clouds made by Atmospheric Chemistry Suite (ACS) onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter (TGO). We analyzed 1663 solar occultation sessions of Thermal InfraRed (TIRVIM) and Middle InfraRed (MIR) channels of ACS covering more than two Martian years that contain spectra of 2.7 μm carbon dioxide ice absorption band<strong>.</strong> That allowed us to unambiguously discriminate carbon dioxide ice aerosols from mineral dust and water ice aerosols, not relying on the information of atmospheric thermal conditions. CO₂ clouds were detected in eleven solar occultation observations at altitudes from 39 km to 90 km. In five cases, there were two or three layers of CO₂ clouds that were vertically separated by 5–15 km gaps. Effective radius of CO₂ aerosol particles is in the range of 0.1–2.2 μm. Spectra produced by the smallest particles indicate a need for a better resolved CO₂ ice refractive index. Nadir optical depth of CO₂ clouds is in the range 5 × 10⁻⁴–4 × 10⁻² at both 2.7 μm and 0.8 μm. Asymmetrical diurnal distribution of detections observed by ACS is potentially due to local time variations of temperature induced by thermal tides. Two out of five cases of carbon dioxide cloud detections made by the TIRVIM instrument reveal the simultaneous presence of CO₂ ice and H₂O ice aerosols. Temperature profiles measured by the Near InfraRed (NIR) channel of ACS are used to calculate CO₂ saturation ratio <em>S</em> at locations of carbon dioxide clouds. Supersaturation S &gt; 1 is detected in only 6 out of 19 cases of CO₂ cloud layers; extremely low values of S &lt; 0.1 are found in 9 out of 19 cases.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"423 ","pages":"Article 116271"},"PeriodicalIF":2.5,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142077018","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}

{"title":"Photometry, rotation period determination and dust coma numerical study of comet C/2017 K2 (PanStarrs)","authors":"R.S. Garcia ,&nbsp;E. Fernández-Lajús ,&nbsp;R.P. Di Sisto ,&nbsp;R.A. Gil-Hutton","doi":"10.1016/j.icarus.2024.116267","DOIUrl":"10.1016/j.icarus.2024.116267","url":null,"abstract":"<div><p>C/2017 K2 (Pan-STARRS) is an Oort cloud comet discovered in May 2017. Ground observations have revealed that this long-period comet was active at a heliocentric distance beyond 20 au. Several studies observed this object when it was far from the Sun and proposed that, at such a distance, its activity is primarily driven by the sublimation of super-volatile ices such as <span><math><mi>CO</mi></math></span> and <span><math><msub><mrow><mi>CO</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>.</p><p>The aim of this paper is to analyze the comet’s dust behavior when it was much closer to the Sun. A series of images were taken on different observation routines between July and August 2022 with the 0.6 m Helen Sawyer Hogg (HSH) telescope at the Complejo Astronómico El Leoncito (CASLEO), using broadband V and R filters. The objective was to conduct a morphological, photometric, and numerical analysis of this comet.</p><p>Digital filters were applied to enhance contrast in the cometary images, revealing an active region embedded within an isotropic coma. Analysis of the magnitudes and dust production rate from the <span><math><mrow><mi>A</mi><mrow><mo>(</mo><mn>0</mn><mo>°</mo><mo>)</mo></mrow><mi>f</mi><mi>ρ</mi></mrow></math></span> parameter suggests a steady-state dust behavior, consistent with findings from other authors.</p><p>Moreover, thanks to the images covering a significant time span, it was possible to determine the comet’s rotation period using a periodogram analysis with the Phase Dispersion Minimization method (PDM) and to calculate the coordinates of the rotation axis, yielding a rotation period of 14.24 h with a pole situated at the ecliptic longitude and latitude of <span><math><mrow><mo>(</mo><mn>244</mn><mo>°</mo><mo>,</mo><mo>−</mo><mn>20</mn><mo>°</mo><mo>)</mo></mrow></math></span>.</p><p>Finally, to gain deeper insights into C/2017 K2’s dust behavior, observations were fitted to a newly developed theoretical model for studying dust comas. The analysis suggests that the comet’s dust coma was principally formed by large dust particles emitted at a velocity of <span><math><mrow><mn>180</mn><mspace></mspace><msup><mrow><mi>ms</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"422 ","pages":"Article 116267"},"PeriodicalIF":2.5,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142021048","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}

{"title":"Graben systems and geological history of Mbokomu Mons region, Parga Chasmata, Venus","authors":"Naima Hannour ,&nbsp;Hafida El Bilali ,&nbsp;Richard E. Ernst ,&nbsp;Kenneth L. Buchan ,&nbsp;James W. Head ,&nbsp;Mohamed Ben Marzoug","doi":"10.1016/j.icarus.2024.116268","DOIUrl":"10.1016/j.icarus.2024.116268","url":null,"abstract":"<div><p>The relationship between chasmata (rift zones) and spatially associated volcanism (mons and coronae) on Venus has been extensively discussed but remains enigmatic. One region where these features are prominently displayed is along the 10,000 km long, WNW trending, Parga Chasmata, which connects Atla Regio with Themis Regio. The Mbokomu Mons area (located about 2200 km SE of Atla Regio) was selected for detailed study to provide insight into these relationships. More than 39,000 extensional lineaments (grabens, fissures and fractures) were mapped at 1:500,000 scale using full resolution Magellan Synthetic Aperture Radar (SAR) images and grouped into radiating, circumferential and linear systems. They are (except where noted) interpreted to represent the surface expression of underlying mafic dyke swarms, on the basis of associated volcanic features and terrestrial analogues. Radiating and/or circumferential swarms are associated with Mbokomu Mons and the four coronae in the surrounding area, Among Corona (AC), Repa Corona (RC) and two unnamed coronae (UC1 and UC2). Mbokomu Mons is unique among the tectono-magmatic features in this region of Parga Chasmata, in having both corona and mons characteristics. The initial Corona Phase consists of radiating and circumferential systems mainly preserved in an unflooded annular uplift, while the Mons Phase includes a second radiating swarm associated with a central edifice, and smaller circumferential fracture pattern near the summit that could overlie a magma reservoir. The plume or diapir that is interpreted to have been responsible for the initial Corona Phase is estimated to have had a radius of ∼150 km. Cross-cutting relationships indicate that Mbokomu Mons is younger than nearby Among, Oduduwa and Onenhtse coronae. All four centres are aligned along a WNW-trend parallel to the Parga Chasmata (rift system). Mbokomu Mons is located at, and its emplacement may be linked to, the intersection of this WNW-trending zone of weakness and the orthogonal Jokwa Linea rift system. Mbokumo Mons is also younger than the nearby parallel Penthesilia Fossa (PF) (part of the Great Dyke of Atla Regio).</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"423 ","pages":"Article 116268"},"PeriodicalIF":2.5,"publicationDate":"2024-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0019103524003282/pdfft?md5=412a1b6a92872bd1cc1caa9b2d4d6a91&pid=1-s2.0-S0019103524003282-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142088922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal cap dynamics at the South Pole of Mars in the 36th Martian year, observed by Tianwen-1","authors":"Zhibin Li ,&nbsp;Jianjun Liu ,&nbsp;Zhaopeng Chen ,&nbsp;Wei Yan ,&nbsp;Zongyu Zhang ,&nbsp;Qing Zhang ,&nbsp;Yuxuan Luo","doi":"10.1016/j.icarus.2024.116266","DOIUrl":"10.1016/j.icarus.2024.116266","url":null,"abstract":"<div><p>The seasonal variation of the Martian South Polar Seasonal Cap (SPSC) is a significant factor to influence Mars atmospheric cycle, which has been continuously observed in previous missions. The SPSC degrades asymmetrically throughout the Martian seasons. However, developing a general description for this asymmetric recession is challenging, and this is crucial for identifying key stages (timesteps) which represents moments of special attribute throughout the recession. Here, we present the Martian Year 36 (MY36) results from the continuous observation of the Martian SPSC by the Moderate Resolution Imaging Camera (MoRIC) onboard the Tianwen-1 orbiter. A time-series of digital orthophoto maps (DOMs) characterizing the south cap were collected ranging from the solar longitude (L_s) 210° to 332°. A seasonal recession model of the cap was established by incorporating a 5th-order polynomial fitting of the time-series on cap latitude, from which the first derivative (recession rate), second derivative (acceleration), and third derivative (jerk) can be obtained. This methodology enables the extraction of critical timesteps that facilitate the categorization of the recession into distinct phases, each characterized by its recession rate and other factors. By the visual interpretation of remote sensing images obtained by Tianwen-1 and the result of timesteps showed that the pause time of the South Polar Residual Cap (SPRC) is about L_s = 324.5°-328° with an area of 7.9 × 10⁴ km². The discrepancies between our results and previous investigations indicate that the Martian climate presents inter-annual fluctuations. The MoRIC image data can be used to quantitatively capture the fine recession dynamic of the southern polar cap.The continuous operation of the Tianwen-1 orbiter will enable further data analysis for the dynamics of the Martian polar caps. This will provide observational constraints for Martian climate models and crucial information for the research of the Martian modern climate.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"422 ","pages":"Article 116266"},"PeriodicalIF":2.5,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040740","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}

{"title":"Collision-induced absorptions by pure CO2 in the infrared: New measurements in the 1150–4500 cm−1 spectral range and empirical modeling for applications","authors":"H. Tran,&nbsp;J.M. Hartmann,&nbsp;E. Rambinison,&nbsp;M. Turbet","doi":"10.1016/j.icarus.2024.116265","DOIUrl":"10.1016/j.icarus.2024.116265","url":null,"abstract":"<div><p>Knowledge of collision-induced absorptions (CIA) by pure CO₂ for wide temperature ranges is necessary for atmospheric and climate studies of planets and exoplanets with CO₂-rich atmospheres. In this work, using spectra measured with a Fourier transform spectrometer for temperatures between 230 K and 295 K at pressures up to 40 bar, several CIA bands in the 1150–4500 cm⁻¹ spectral range have been determined, in some cases for the first time. The results are compared with values reported in the literature, showing good agreements. From data obtained in this work and those in the literature, we propose simple analytical models for the temperature dependent band shape and integrated band intensity (IBI) which enable the calculation of all investigated CIA transitions in a wide temperature range.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"422 ","pages":"Article 116265"},"PeriodicalIF":2.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040741","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}

{"title":"Ice degradation and Boulder size frequency distribution analysis of the fresh Martian crater S1094b","authors":"Filippo Tusberti ,&nbsp;Maurizio Pajola ,&nbsp;Giovanni Munaretto ,&nbsp;Luca Penasa ,&nbsp;Alice Lucchetti ,&nbsp;Joel Beccarelli ,&nbsp;Costanza Rossi ,&nbsp;Riccardo Pozzobon ,&nbsp;Matteo Massironi","doi":"10.1016/j.icarus.2024.116255","DOIUrl":"10.1016/j.icarus.2024.116255","url":null,"abstract":"<div><p>S1094b is the largest (155 m-size) and southernmost known ice-exposing fresh crater discovered so far on Mars, revealing a relatively pure and unstable subsurface ice deposit located at the northern Martian mid-latitudes. In this work, we analyze HiRISE images taken on 27 February 2022 and on 5 December 2022 to perform a multi-temporal analysis of its ice-rich ejecta, combining this analysis with geologic mapping, the boulder size frequency distribution (SFD) and thermal modeling. The objective is to provide a multidisciplinary characterization of both the impact and subsequent exposed ice sublimation processes. The boulder SFD of both February and December cases show a power-law best fit with indices −4.68 ± 0.15 and − 3.47 ± 0.10, respectively. In the same timeframe, the density of boulders per km² ≥ 1.5 m changes from 3908, to 596. This flattening is mainly due to the sublimation and consequent loss of the smaller-size icy boulders. This is confirmed by the ice volume computation performed on the area, which changed from ∼20,274 ± 3997 m³ to ∼7951 ± 1117 m³, i.e. a decrease of ∼60% in 274 Sols. The thermal models showed that the ice in this region is always unstable, leading to a total of 6504.71 sublimation hours from which we estimated a sublimation rate of ∼0.15 ± 0.04 mm/h (i.e. ∼3.60 ± 0.96 mm/Sol). The presence of this amount of accessible ice at such low latitudes could be a valuable resource for potential future human missions.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"423 ","pages":"Article 116255"},"PeriodicalIF":2.5,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0019103524003154/pdfft?md5=0f15fb53015b31262f412b949f22d817&pid=1-s2.0-S0019103524003154-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142049789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of a large buried impact crater and vertical mineral composition at the Chang'E-4 landing site by multi-source remote sensing data","authors":"Shurui Chen,&nbsp;Yongjiu Feng,&nbsp;Xiaohua Tong,&nbsp;Huan Xie,&nbsp;Chao Wang,&nbsp;Xiong Xu,&nbsp;Yanmin Jin,&nbsp;Sicong Liu,&nbsp;Changjiang Xiao,&nbsp;Qiquan Yang,&nbsp;Hui Zhao,&nbsp;Kecheng Du","doi":"10.1016/j.icarus.2024.116256","DOIUrl":"10.1016/j.icarus.2024.116256","url":null,"abstract":"<div><p>Exploring the concealed subsurface structures and materials beneath the lunar surface can reveal significant insights into geological history. This study offers a comprehensive analysis of the stratigraphic interpretation and subsurface material composition at the Chang'E-4 landing site, integrating both in-situ and orbital radar with multispectral datasets. We report the identification of a subsurface structure, which resembles a buried impact crater (∼420 m in diameter) under the Yutu-2 rover's path. This crater could degrade over a period of 0.42 to 0.53 Ga, with an initial diameter of 293 to 323 m and an initial depth of 45.9 to 51.4 m. Surface material above the buried crater, evaluated by the in-situ visible and near-infrared imaging spectrometer (VNIS) detector, shows a higher abundance of clinopyroxene compared to surrounding areas, where a near-equal mix of clinopyroxene and orthopyroxene is observed. Assessment of crater diameters in proximity to the Chang'E-4 landing site, along with the mineral compositions at their epicenters, reveals a decrease in the abundance of clinopyroxene and plagioclase with depth. Conversely, the quantities of orthopyroxene and olivine increase, implying that orthopyroxene-rich Finsen ejecta significantly influenced the Chang'E-4 landing site's geological composition. Two potential stratigraphic boundary depths are identified at 13.5 and 22 m, based on pronounced variations in mineral abundance, offering fresh insights into subsurface delineation beyond radar data. Considering the VNIS and vertical mineral composition, we propose the buried crater's formation resulted from Finsen crater's ejecta. Also, we identify eight potential historical impacts by comparing subsurface relief variations with mineral composition ratios between clinopyroxene and orthopyroxene. The integration of subsurface structure, along with surface and subsurface mineral composition, enables a more robust stratigraphic interpretation, facilitates shallow material source analysis, and allows for historical impact tracing.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"422 ","pages":"Article 116256"},"PeriodicalIF":2.5,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141979270","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}

{"title":"Lunar simulant behaviour variability and implications on terrestrial based lunar testing","authors":"Philipp Zanon,&nbsp;Michelle Dunn,&nbsp;Geoffrey Brooks","doi":"10.1016/j.icarus.2024.116257","DOIUrl":"10.1016/j.icarus.2024.116257","url":null,"abstract":"<div><p>The detrimental effects and challenges of Lunar dust for Lunar exploitation were first identified during the Apollo missions. During the extra vehicle activities (EVAs) undertaken by astronauts, the dust clogged mechanisms, disrupted sensors, and caused several health issues for the astronauts. Despite numerous studies, there is no definite understanding as to why different Apollo missions experienced varying levels of dust disruptions. The variations in dust behaviour could be attributed to the amount of radiation the Lunar soil is exposed to, as well as mineralogy and particle sizes. To enhance our understanding of Lunar dust behaviour this study investigated Space Recourse Technologies, formally known as Exolith, simulant at different mineral compositions, and their surface detachment characteristics were measured. Experiments measuring the individual minerals and their mixed simulant-like counterparts were conducted using electrostatic fields. Inclusive to this, non-dried and dried samples were compared by measuring adhesion to target plates when subject to electrostatic forces. The results found that Highlands simulant exhibited a higher buildup on a target plate than its Mare counterpart by an average of 33% under the same conditions, likely due to particle size differences. In addition to these findings, evidence of particle reactivity decay was observed under repeated tests with up to 60% less Mare simulant and 36% Highlands deposition being measured compared to the first set of experiments. A possible explanation may be particle reactivity. Microscope images identified that particles are transported in groups as opposed to individual grains. These results will help researchers in tailoring dust mitigation solutions based on different regions on the Lunar surface and influence mission planning from the perspective of dust mitigation and contamination.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"422 ","pages":"Article 116257"},"PeriodicalIF":2.5,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0019103524003178/pdfft?md5=a3c15cea179e35faa63369af1262e83a&pid=1-s2.0-S0019103524003178-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142021047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamical evolution of the Uranian satellite system II. Crossing of the 5/3 Ariel–Umbriel mean motion resonance","authors":"Sérgio R.A. Gomes ,&nbsp;Alexandre C.M. Correia","doi":"10.1016/j.icarus.2024.116254","DOIUrl":"10.1016/j.icarus.2024.116254","url":null,"abstract":"<div><p>At present, the main satellites of Uranus are not involved in any low order mean motion resonance (MMR). However, owing to tides raised in the planet, Ariel and Umbriel most likely crossed the 5/3 MMR in the past. Previous studies on this resonance passage relied on limited time-consuming <span><math><mrow><mi>N</mi><mo>−</mo></mrow></math></span>body simulations or simplified models focusing solely on the effects of the eccentricity or the inclination. In this paper, we aim to provide a more comprehensive view on how the system evaded capture in the 5/3 MMR. For that purpose, we developed a secular resonant two-satellite model with low eccentricities and low inclinations, including tides using the weak friction model. By performing a large number of numerical simulations, we show that capture in the 5/3 MMR is certain if the initial eccentricities of Ariel, <span><math><msub><mrow><mi>e</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>, and Umbriel, <span><math><msub><mrow><mi>e</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, are related through <span><math><mrow><msup><mrow><mrow><mo>(</mo><msubsup><mrow><mi>e</mi></mrow><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>+</mo><msubsup><mrow><mi>e</mi></mrow><mrow><mn>2</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>)</mo></mrow></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>007</mn></mrow></math></span>. Moreover, we observe that the eccentricity of Ariel is the key variable to evade the 5/3 MMR with a high probability. We determine that for <span><math><mrow><msub><mrow><mi>e</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>&gt;</mo><mn>0</mn><mo>.</mo><mn>015</mn></mrow></math></span> and <span><math><mrow><msub><mrow><mi>e</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>&lt;</mo><mn>0</mn><mo>.</mo><mn>01</mn></mrow></math></span>, the system avoids capture in at least 60% of the cases. We also show that, to replicate the currently observed system, the initial inclinations of Ariel and Umbriel must lay within <span><math><mrow><msub><mrow><mi>I</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>≤</mo><mn>0</mn><mo>.</mo><mn>05</mn><mo>°</mo></mrow></math></span> and <span><math><mrow><mn>0</mn><mo>.</mo><mn>06</mn><mo>°</mo><mo>≤</mo><msub><mrow><mi>I</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>≤</mo><mn>0</mn><mo>.</mo><mn>11</mn><mo>°</mo></mrow></math></span>, respectively. We checked these results using a complete <span><math><mrow><mi>N</mi><mo>−</mo></mrow></math></span>body model with the five main satellites and did not observe any significant differences.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"424 ","pages":"Article 116254"},"PeriodicalIF":2.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0019103524003142/pdfft?md5=ead07189642683424e1c775ea533b5cc&pid=1-s2.0-S0019103524003142-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatially dependent hydration features on nominally anhydrous near-earth asteroids","authors":"L.E. McGraw ,&nbsp;J.P. Emery ,&nbsp;C.A. Thomas ,&nbsp;A.R. Rivkin","doi":"10.1016/j.icarus.2024.116252","DOIUrl":"10.1016/j.icarus.2024.116252","url":null,"abstract":"<div><p>Near-Earth Asteroids (NEAs) are excellent laboratories for processes that affect the surfaces of airless bodies. Most NEAs were not expected to contain OH/H₂O on their surfaces because they are primarily S-complex objects and sourced from the inner Main Belt, which is interior of the frost line, and their surface temperatures are high enough to remove these volatiles. However, a 3-μm feature typically indicative of OH/H₂O was identified on other seemingly dry bodies in the inner Solar System, such as the Moon and Vesta, and more recently on the NEAs (433) Eros, (1036) Ganymed, and (3122) Florence. The most likely sources for OH/H₂O on these bodies include carbonaceous chondrite impacts or interactions with protons implanted by solar wind. We investigated the causes of band depth and shape variations on NEAs by comparing new observations of Eros and Ganymed to those previously published and conducting a rotationally-resolved spectral study on Florence. All spectra discussed were collected by SpeX on NASA's IRTF using the LXD_short (1.67–4.2 μm) mode to characterize the 3-μm region. Some observations also used the prism (0.7–2.52 μm) mode to characterize asteroid spectral type and investigate silicate composition dependencies. All three asteroids possess exogenously sourced OH/H₂O and have spectra that show potential spatially correlated variations in band depth or shape. Eros' band is slightly wider at the poles than at lower sub-observer latitudes, possibly due to its high obliquity, which ensures that each polar region is oriented toward the Sun over a significant part of its orbit. Ganymed's trends in hydration band depth with sub-solar longitude and band I center suggest a carbonaceous or cometary impactor that struck the surface around 0° relative longitude, excavating a relatively magnesium- and olivine-enriched layer. Florence's total hydrogen concentration remains stable across the surface even as the OH-to-H₂O ratio changes as the asteroid rotates. These three examples suggest that non-native OH/H₂O on other bodies will likely also be spatially dependent, regardless of delivery mechanism.</p></div>","PeriodicalId":13199,"journal":{"name":"Icarus","volume":"422 ","pages":"Article 116252"},"PeriodicalIF":2.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0019103524003129/pdfft?md5=ad21b61700b04183a0241116f5447c54&pid=1-s2.0-S0019103524003129-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141963804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}