Preliminary analyses of asteroid Ryugu samples show kinship to aqueously altered CI (Ivuna-type) chondrites,
suggesting similar origins. We report identification of C-rich, particularly primitive clasts in Ryugu samples that
contain preserved presolar silicate grains and exceptional abundances of presolar SiC and isotopically anomalous organic matter. The high presolar silicate abundance (104 ppm) indicates that the clast escaped extensive
alteration. The 5 to 10 times higher abundances of presolar SiC (~235 ppm), N-rich organic matter, organics with
N isotopic anomalies (1.2%), and organics with C isotopic anomalies (0.2%) in the primitive clasts compared to
bulk Ryugu suggest that the clasts formed in a unique part of the protoplanetary disk enriched in presolar materials. These clasts likely represent previously unsampled outer solar system material that accreted onto Ryugu
after aqueous alteration ceased, consistent with Ryugu’s rubble pile origin.
Preserved flora and organics in impact melt brecciasCarlos Bella
This document discusses the preservation of organic matter and plant remains in impact melt breccias found in Argentina. Analyses found centimeter-scale leaf fragments encapsulated in the impact glass that exhibited remarkable cellular-level preservation. Organic matter was also detected, including polycyclic aromatic hydrocarbons, alkanes, and pigment-like structures similar to chlorophyll. Heating experiments showed temperatures above 1500°C were required to preserve morphology, suggesting the impact process rapidly quenched and encapsulated the organic material. These findings demonstrate the potential for impact events to preserve biomarkers of early life on Mars.
Localized aliphatic organic material on the surface of CeresSérgio Sacani
This document summarizes research on the detection of organic material on the surface of the dwarf planet Ceres. Spectral data from the Dawn spacecraft's VIR instrument shows a clear detection of an organic absorption feature at 3.4 micrometers localized near the Ernutet crater on Ceres. This signature is characteristic of aliphatic organic matter. The presence of organics as well as other compounds like ammonia-bearing minerals, water ice, carbonates and salts indicates a complex chemical environment on Ceres that could be favorable for prebiotic chemistry. The organics are concentrated in a 1000 square kilometer region near Ernutet crater, and their origin is unclear but may be from an impactor or endogenous to Ceres
The Influence of Vermiculite on the Uptake of Silver Nanoparticles in a Terre...Agriculture Journal IJOEAR
— The uptake of silver from silver nanoparticles in soil was investigated in the presence of increasing concentrations of Vermiculite, typical 2:1 clay. Two insect species, Acheta domesticus and Tenebrio molitor, and two plant species, Helianthus annuus and Sorghum vulgare, were exposed to silver nanoparticles in the presence of increasing concentrations of Vermiculite in soil. Silver nanoparticles were characterized using techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The levels of silver in test species exposed to silver nanoparticles were measured using an inductively coupled plasma-optical emission spectrometer. An increase in the cation exchange capacity of soil was observed with the increase in the concentration of vermiculite in soil. The results suggested a decrease in the uptake of silver from silver nanoparticles in soil by Acheta domesticus as a function of increasing concentrations of Vermiculite in soil. No apparent trend was observed in the remaining species. Both plant species were found to accumulate silver in their roots. The translocation of silver to stems and leaves was observed in the case of Helianthus annuus. Results from this study suggest that the presence of Vermiculite in soil could possibly decrease the uptake of silver from silver nanoparticles.
A geochemical assessment of soils within oke ogun area, southwestern nigeriaAlexander Decker
This document summarizes a study that analyzed soil samples from Oke-Ogun area in southwestern Nigeria to investigate concentrations of major elements and trace metals.
Key findings include:
1. Soil samples showed elevated levels of Pb, Cr, V, Mn, and Co compared to underlying bedrock, indicating enrichment during weathering.
2. Statistical analysis revealed associations between Cu-Pb-Cd-Ni-Co and Zn-V.
3. Principal component analysis identified three factors associated with differing sources for trace metals in the soils.
An Earth Scientists Periodic Table Of The Elements And Their IonsKatie Naple
This document presents a new periodic table of elements and their ions organized by charge rather than element. This Earth Scientist's Periodic Table groups elements based on how they commonly occur in geochemical processes like mineral formation, seawater chemistry, and nutrient cycling. It shows many elements multiple times to represent their different charged states in nature. This organization reveals trends and relationships between elements that are not apparent in the conventional periodic table, providing earth scientists a more effective framework for understanding geochemistry.
W. van schmus natural radioactivity of the crust and mantle [short article]...Iasmy Maria-iasmina
This document summarizes the natural radioactivity of the Earth's crust and mantle. It discusses the abundance and distribution of the major radioactive nuclides potassium-40, uranium-238, uranium-235, and thorium-232 in rocks and minerals. It also describes the decay processes of these nuclides, which produce heat within the Earth and are used in geochronology and tracing geological processes. The abundances of these radionuclides vary over orders of magnitude in different rock types, providing constraints on models of the Earth's composition and thermal history.
This study uses in situ characterization techniques to analyze five solid inclusions found in diamonds from Siberia. The inclusions are identified as upper mantle minerals including olivine, enstatite orthopyroxene, omphacite clinopyroxene, and two grains of majoritic garnet. Synchrotron X-ray microfluorescence, diffraction, and Raman spectroscopy indicate the inclusions have a homogeneous eclogitic composition and formed under high temperatures and reducing conditions in the upper mantle. X-ray absorption near edge spectroscopy shows the iron in the inclusions is predominantly in the ferrous state, suggesting low oxygen fugacity during formation.
Magnesium isotope evidence that accretional vapour loss shapes planetary comp...Sérgio Sacani
It has long been recognized that Earth and other differentiated
planetary bodies are chemically fractionated compared to primitive,
chondritic meteorites and, by inference, the primordial disk
from which they formed. However, it is not known whether the
notable volatile depletions of planetary bodies are a consequence
of accretion1
or inherited from prior nebular fractionation2
. The
isotopic compositions of the main constituents of planetary bodies
can contribute to this debate3–6. Here we develop an analytical
approach that corrects a major cause of measurement inaccuracy
inherent in conventional methods, and show that all differentiated
bodies have isotopically heavier magnesium compositions
than chondritic meteorites. We argue that possible magnesium
isotope fractionation during condensation of the solar nebula,
core formation and silicate differentiation cannot explain these
observations. However, isotopic fractionation between liquid and
vapour, followed by vapour escape during accretionary growth of
planetesimals, generates appropriate residual compositions. Our
modelling implies that the isotopic compositions of magnesium,
silicon and iron, and the relative abundances of the major elements
of Earth and other planetary bodies, are a natural consequence of
substantial (about 40 per cent by mass) vapour loss from growing
planetesimals by this mechanism.
Preserved flora and organics in impact melt brecciasCarlos Bella
This document discusses the preservation of organic matter and plant remains in impact melt breccias found in Argentina. Analyses found centimeter-scale leaf fragments encapsulated in the impact glass that exhibited remarkable cellular-level preservation. Organic matter was also detected, including polycyclic aromatic hydrocarbons, alkanes, and pigment-like structures similar to chlorophyll. Heating experiments showed temperatures above 1500°C were required to preserve morphology, suggesting the impact process rapidly quenched and encapsulated the organic material. These findings demonstrate the potential for impact events to preserve biomarkers of early life on Mars.
Localized aliphatic organic material on the surface of CeresSérgio Sacani
This document summarizes research on the detection of organic material on the surface of the dwarf planet Ceres. Spectral data from the Dawn spacecraft's VIR instrument shows a clear detection of an organic absorption feature at 3.4 micrometers localized near the Ernutet crater on Ceres. This signature is characteristic of aliphatic organic matter. The presence of organics as well as other compounds like ammonia-bearing minerals, water ice, carbonates and salts indicates a complex chemical environment on Ceres that could be favorable for prebiotic chemistry. The organics are concentrated in a 1000 square kilometer region near Ernutet crater, and their origin is unclear but may be from an impactor or endogenous to Ceres
The Influence of Vermiculite on the Uptake of Silver Nanoparticles in a Terre...Agriculture Journal IJOEAR
— The uptake of silver from silver nanoparticles in soil was investigated in the presence of increasing concentrations of Vermiculite, typical 2:1 clay. Two insect species, Acheta domesticus and Tenebrio molitor, and two plant species, Helianthus annuus and Sorghum vulgare, were exposed to silver nanoparticles in the presence of increasing concentrations of Vermiculite in soil. Silver nanoparticles were characterized using techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The levels of silver in test species exposed to silver nanoparticles were measured using an inductively coupled plasma-optical emission spectrometer. An increase in the cation exchange capacity of soil was observed with the increase in the concentration of vermiculite in soil. The results suggested a decrease in the uptake of silver from silver nanoparticles in soil by Acheta domesticus as a function of increasing concentrations of Vermiculite in soil. No apparent trend was observed in the remaining species. Both plant species were found to accumulate silver in their roots. The translocation of silver to stems and leaves was observed in the case of Helianthus annuus. Results from this study suggest that the presence of Vermiculite in soil could possibly decrease the uptake of silver from silver nanoparticles.
A geochemical assessment of soils within oke ogun area, southwestern nigeriaAlexander Decker
This document summarizes a study that analyzed soil samples from Oke-Ogun area in southwestern Nigeria to investigate concentrations of major elements and trace metals.
Key findings include:
1. Soil samples showed elevated levels of Pb, Cr, V, Mn, and Co compared to underlying bedrock, indicating enrichment during weathering.
2. Statistical analysis revealed associations between Cu-Pb-Cd-Ni-Co and Zn-V.
3. Principal component analysis identified three factors associated with differing sources for trace metals in the soils.
An Earth Scientists Periodic Table Of The Elements And Their IonsKatie Naple
This document presents a new periodic table of elements and their ions organized by charge rather than element. This Earth Scientist's Periodic Table groups elements based on how they commonly occur in geochemical processes like mineral formation, seawater chemistry, and nutrient cycling. It shows many elements multiple times to represent their different charged states in nature. This organization reveals trends and relationships between elements that are not apparent in the conventional periodic table, providing earth scientists a more effective framework for understanding geochemistry.
W. van schmus natural radioactivity of the crust and mantle [short article]...Iasmy Maria-iasmina
This document summarizes the natural radioactivity of the Earth's crust and mantle. It discusses the abundance and distribution of the major radioactive nuclides potassium-40, uranium-238, uranium-235, and thorium-232 in rocks and minerals. It also describes the decay processes of these nuclides, which produce heat within the Earth and are used in geochronology and tracing geological processes. The abundances of these radionuclides vary over orders of magnitude in different rock types, providing constraints on models of the Earth's composition and thermal history.
This study uses in situ characterization techniques to analyze five solid inclusions found in diamonds from Siberia. The inclusions are identified as upper mantle minerals including olivine, enstatite orthopyroxene, omphacite clinopyroxene, and two grains of majoritic garnet. Synchrotron X-ray microfluorescence, diffraction, and Raman spectroscopy indicate the inclusions have a homogeneous eclogitic composition and formed under high temperatures and reducing conditions in the upper mantle. X-ray absorption near edge spectroscopy shows the iron in the inclusions is predominantly in the ferrous state, suggesting low oxygen fugacity during formation.
Magnesium isotope evidence that accretional vapour loss shapes planetary comp...Sérgio Sacani
It has long been recognized that Earth and other differentiated
planetary bodies are chemically fractionated compared to primitive,
chondritic meteorites and, by inference, the primordial disk
from which they formed. However, it is not known whether the
notable volatile depletions of planetary bodies are a consequence
of accretion1
or inherited from prior nebular fractionation2
. The
isotopic compositions of the main constituents of planetary bodies
can contribute to this debate3–6. Here we develop an analytical
approach that corrects a major cause of measurement inaccuracy
inherent in conventional methods, and show that all differentiated
bodies have isotopically heavier magnesium compositions
than chondritic meteorites. We argue that possible magnesium
isotope fractionation during condensation of the solar nebula,
core formation and silicate differentiation cannot explain these
observations. However, isotopic fractionation between liquid and
vapour, followed by vapour escape during accretionary growth of
planetesimals, generates appropriate residual compositions. Our
modelling implies that the isotopic compositions of magnesium,
silicon and iron, and the relative abundances of the major elements
of Earth and other planetary bodies, are a natural consequence of
substantial (about 40 per cent by mass) vapour loss from growing
planetesimals by this mechanism.
This document summarizes spectroscopic evidence from electronic absorption, magnetic circular dichroism (MCD), and resonance Raman spectroscopies that provide insight into the unique bonding interaction in oxo-molybdenum dithiolate complexes. The data suggests these complexes have low-energy sulfur to molybdenum charge transfer transitions originating from a set of four filled dithiolate orbitals that are primarily sulfur in character. Resonance Raman excitation profiles allowed assignment of an ene-dithiolate in-plane sulfur to molybdenum transition. Three totally symmetric vibrational modes were also identified. The results provide context for understanding electron transfer pathways in pyranopterin dithiolate centers
Effect of Concentration of Silver Nanoparticles on the Uptake of Silver from ...Agriculture Journal IJOEAR
— The bioavailability and uptake of silver from silver nanoparticles in soil was investigated. Two species of insects, Acheta domesticus and Tenebrio molitor, and two species of plants, Helianthus annuus and Sorghum vulgare, were exposed to a range of concentrations of silver nanoparticles in soil. Silver nanoparticles were charactrized by techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The concentration of silver in insects and plants exposed to silver nanoparticles was measured using inductively coupled plasma-optical emission spectrometry. The results suggested an increase in the levels of silver in both insects and plants as a function of increasing concentrations of silver nanoparticles in soil. The translocation of silver to various parts of dicot plants such as stems and leaves was also observed. Such a result was not observed in the case of monocot plants. Results from this study suggests that silver nanoparticles would be available for uptake by insects and plants in terrestrial ecosystems.
Geochemistry involves studying the chemical composition of Earth and other planets, as well as the chemical processes that govern rocks, water, and soils. It examines how chemical elements are distributed and move through different parts of Earth over time. Key techniques for geochemical analysis include electron probe microanalysis and X-ray fluorescence spectrometry. Proper interpretation of geochemical data requires considering analytical uncertainty and discussing limitations with laboratory experts.
Hydrogen-bearing vesicles in space weathered lunar calcium-phosphatesSérgio Sacani
Water on the surface of the Moon is a potentially vital resource for future lunar bases and
longer-range space exploration. Effective use of the resource depends on developing an
understanding of where and how within the regolith the water is formed and retained. Solar
wind hydrogen, which can form molecular hydrogen, water and/or hydroxyl on the lunar
surface, reacts and is retained differently depending on regolith mineral content, thermal
history, and other variables. Here we present transmission electron microscopy analyses of
Apollo lunar soil 79221 that reveal solar-wind hydrogen concentrated in vesicles as molecular
hydrogen in the calcium-phosphates apatite and merrillite. The location of the vesicles in the
space weathered grain rims offers a clear link between the vesicle contents and solar wind
irradiation, as well as individual grain thermal histories. Hydrogen stored in grain rims is a
source for volatiles released in the exosphere during impacts.
The document describes a study that used a combination of particle induced x-ray emission (PIXE), Rutherford backscattering spectroscopy (RBS), and x-ray diffraction (XRD) to characterize pottery from the Epiclassic period in Teotihuacan, Mexico. PIXE and RBS were used to determine the elemental compositions of 19 pottery samples, while XRD identified the mineral phases present. The results showed that most pottery samples had similar compositions, but two samples had distinct elemental profiles, suggesting a different origin. The study provided information on pottery production and resources during the decline of the Teotihuacan civilization.
Prebiosignature Molecules Can Be Detected in Temperate Exoplanet Atmospheres ...Sérgio Sacani
The search for biosignatures on exoplanets connects the fields of biology and biochemistry to astronomical observation, with the hope that we might detect evidence of active biological processes on
worlds outside the solar system. Here we focus on a complementary aspect of exoplanet characterisation connecting astronomy to prebiotic chemistry: the search for molecules associated with the origin
of life, prebiosignatures. Prebiosignature surveys in planetary atmospheres offer the potential to both
constrain the ubiquity of life in the galaxy and provide important tests of current prebiotic syntheses
outside of the laboratory setting. Here, we quantify the minimum abundance of identified prebiosignature molecules that would be required for detection by transmission spectroscopy using JWST. We
consider prebiosignatures on five classes of terrestrial planet: an ocean planet, a volcanic planet, a
post-impact planet, a super-Earth, and an early Earth analogue. Using a novel modelling and detection test pipeline, with simulated JWST noise, we find the detection thresholds of hydrogen cyanide
(HCN), hydrogen sulfide (H2S), cyanoacetylene (HC3N), ammonia (NH3), methane (CH4), acetylene
(C2H2), sulfur dioxide (SO2), nitric oxide (NO), formaldehyde (CH2O), and carbon monoxide (CO) in
a variety of low mean molecular weight (< 5) atmospheres. We test the dependence of these detection
thresholds on M dwarf target star and the number of observed transits, finding that a modest number
of transits (1-10) are required to detect prebiosignatures in numerous candidate planets, including
TRAPPIST-1e with a high mean molecular weight atmosphere. We find that the NIRSpec G395M/H
instrument is best suited for detecting most prebiosignatures.
Volatile and organic_composition_of_sedimentary_rocks_in_yellowknife_bay_gale...Sérgio Sacani
This document summarizes the results of experiments analyzing the volatile and organic compositions of sedimentary rock samples from Yellowknife Bay in Gale Crater, Mars. The samples were obtained using the Curiosity rover's drill. Analysis found the samples released water, carbon dioxide, sulfur dioxide, oxygen, and other gases when heated. The water and oxygen releases suggest the presence of hydrated minerals like phyllosilicates and oxychlorine compounds. Small amounts of organic compounds, including chlorinated hydrocarbons, were also detected, though the carbon source is uncertain. The sediments appear to have preserved evidence of past environmental conditions and potential habitability in Yellowknife Bay.
This document summarizes a student research project on analyzing heavy metal contamination in the plant Celosia argentea collected from four different locations. The student describes collecting plant samples, using atomic absorption spectrometry to determine metal concentrations, and finding that levels of metals like iron, copper, zinc, manganese, and chromium were below permissible limits set by the FAO and WHO. However, the student notes that farming along roadsides should still be discouraged due to potential heavy metal pollution from vehicular traffic.
Synthesis of prebiotic organics from CO2 by catalysis with meteoritic and vo...Sérgio Sacani
The emergence of prebiotic organics was a mandatory step toward the origin of life. The signifcance
of the exogenous delivery versus the in-situ synthesis from atmospheric gases is still under debate.
We experimentally demonstrate that iron-rich meteoritic and volcanic particles activate and catalyse
the fxation of CO2, yielding the key precursors of life-building blocks. This catalysis is robust and
produces selectively aldehydes, alcohols, and hydrocarbons, independent of the redox state of the
environment. It is facilitated by common minerals and tolerates a broad range of the early planetary
conditions (150–300 °C, ≲ 10–50 bar, wet or dry climate). We fnd that up to 6 × 108 kg/year of prebiotic
organics could have been synthesized by this planetary-scale process from the atmospheric CO2 on
Hadean Earth.
This document analyzes the magnesium isotopic compositions of 47 lunar samples including mare basalts, highland rocks, regolith breccias, and lunar soils. The samples show a range of magnesium isotopic values from -0.61‰ to 0.02‰ in mare basalts and -0.34‰ to -0.18‰ in highland rocks. Limited variation is observed among lunar soils and breccias, but large fractionation is seen between low-Ti and high-Ti basalts. Overall, the Moon has a magnesium isotopic composition indistinguishable from Earth and chondrites, suggesting homogeneous distribution in the solar system without fractionation during the Moon-forming giant impact
Unique chemistry of a diamond-bearing pebble from the Libyan Desert Glass str...Carlos Bella
This document summarizes research on a unique black, shiny, and intensely fractured stone named "Hypatia" found in the Libyan Desert Glass strewnfield in southwest Egypt. Analysis showed the stone is composed primarily of amorphous carbonaceous matter containing nanodiamonds. Isotopic signatures of carbon and noble gases rule out a terrestrial origin and match cometary materials. The researchers propose Hypatia is a remnant of a comet nucleus fragment that was incorporated into the bolide that created the Libyan Desert Glass in an atmospheric airburst event 28.5 million years ago. Its shock transformation produced a weathering-resistant material that has been exceptionally preserved.
This document analyzes the magnesium isotopic compositions of 22 differentiated meteorites from 7 types of achondrites and pallasite meteorites. It finds:
1) Achondrites have d26Mg values ranging from -0.369‰ to -0.158‰, with most compositions similar and showing no significant isotopic fractionation.
2) However, some angrites and howardite-eucrite-diogenite (HED) meteorites have slightly heavier Mg isotopic compositions, possibly due to impact evaporation or higher clinopyroxene abundances.
3) The average Mg isotopic composition of achondrites (-0.246‰) is indistinguish
This document summarizes a study that uses geochemical modeling to constrain the possible composition of Europa's subsurface ocean and seafloor. The study models how seven different candidate bulk accretionary materials for Europa (various carbonaceous and ordinary chondrites) would alter through water-rock reactions. The models produce ocean compositions within 10% of previous estimates and indicate that precipitation of different mineral phases could depend on the rock type. Ordinary chondrites may produce higher calcium ion levels in Europa's present-day ocean compared to carbonaceous materials. Future missions could help determine Europa's actual accretionary material by detecting these mineral signatures or ocean chemistry.
1) The document describes an experiment where an ice mixture simulating interstellar medium composition was ultraviolet irradiated at 12K and analyzed after warming.
2) 16 amino acids were detected in the residue, including some that are also found in meteorites. Chiral amino acids showed enantiomeric separation.
3) The results demonstrate that amino acids can be spontaneously generated in interstellar ice analogs upon ultraviolet irradiation, supporting the hypothesis that amino acids could have been delivered to Earth by comets or meteorites.
The Primary Source of Mercury in the Subsoil and Environmental Impacts AJASTJournal
The paper aims to figure out the primary source of mercury in the subsoil and environmental impacts.
By using descriptive method for primary model, synthesis methods and process analysis and analysis of difficulties and discussion, The study of this problem point that, The primary source of mercury in the subsoil is considered to be deep exhalations coming from with the activation of deep processes - geothermal, eruptive, etc., and its intensive rocks enriched with organic matter become an accumulator in the sedimentary cover -carbonaceous formations and soil layer. It is from the latter that she again enters biocycle with a new stage of intravital accumulation in plant and animal organisms in the greater the amount, the higher its content in the environment. Moreover, it is also observed.
The Primary Source of Mercury in the Subsoil and Environmental Impacts IIJSRJournal
The paper aims to figure out the primary source of mercury in the subsoil and environmental impacts.
By using descriptive method for primary model, synthesis methods and process analysis and analysis of difficulties and discussion, The study of this problem point that, The primary source of mercury in the subsoil is considered to be deep exhalations coming from with the activation of deep processes - geothermal, eruptive, etc., and its intensive rocks enriched with organic matter become an accumulator in the sedimentary cover -carbonaceous formations and soil layer. It is from the latter that she again enters biocycle with a new stage of intravital accumulation in plant and animal organisms in the greater the amount, the higher its content in the environment. Moreover, it is also observed.
Rishav Prakash discusses heavy metal removal technologies. Trace amounts of heavy metals like copper, iron, and zinc are required by organisms, but excessive levels can be toxic. Sources of heavy metals include mining, agriculture, solid waste, automobiles, and fossil fuel emissions. Removal technologies discussed include reverse osmosis, precipitation, ion exchange, adsorption, and biosorption. Biosorption is the passive binding of heavy metals by inactive biomass like algae, fungi, and bacteria through mechanisms like adsorption, ion exchange, complexation, and precipitation. Obligate halophilic fungi like Aspergillus flavus and Sterigmatomyces halophilus show potential for biosorbing cadm
Iron acquisition and mineral transformation by cyanobacteria living in extrem...Sérgio Sacani
Iron is an essential micronutrient for most living organisms, including cyanobacteria. These microorganisms have
been found in Earth's driest polar and non-polar deserts, including the Atacama Desert, Chile. Iron-containing
minerals were identified in colonized rock substrates from the Atacama Desert, however, the interactions be-
tween microorganisms and iron minerals remain unclear. In the current study, we determined that colonized
gypsum rocks collected from the Atacama Desert contained both magnetite and hematite phases. A cyanobacteria
isolate was cultured on substrates consisting of gypsum with embedded magnetite nanoparticles. Transmission
electron microscopy imaging revealed a significant reduction in the size of magnetite nanoparticles due to their
dissolution, which occurred around the microbial biofilms. Concurrently, hematite was detected, likely from the
oxidation of the magnetite nanoparticles. Higher cell counts and production of siderophores were observed in
cultures with magnetite nanoparticles suggesting that cyanobacteria were actively acquiring iron from the
magnetite nanoparticles. Magnetite dissolution and iron acquisition by the cyanobacteria was further confirmed
using large bulk magnetite crystals, uncovering a survival strategy of cyanobacteria in these extreme
environments.
This study explores the petrography, chemistry, and cooling rates of the LL-chondrite meteorite LAR 12325 in order to understand its formation history. Petrographic analysis found the meteorite consists of clasts embedded in an impact melt matrix, indicating it experienced shock metamorphism from an asteroid impact. Chemical compositions of minerals in the clasts and melt are consistent with an LL-chondrite. Fast initial cooling rates of 27-247°C/s were estimated, but commonly used methods to estimate longer-term cooling rates do not apply to LL-chondrites with high metal nickel content. The parent asteroid underwent thermal metamorphism before being impacted, melted, and rapidly cooled
The Limited Role of the Streaming Instability during Moon and Exomoon FormationSérgio Sacani
It is generally accepted that the Moon accreted from the disk formed by an impact between the proto-Earth and
impactor, but its details are highly debated. Some models suggest that a Mars-sized impactor formed a silicate
melt-rich (vapor-poor) disk around Earth, whereas other models suggest that a highly energetic impact produced a
silicate vapor-rich disk. Such a vapor-rich disk, however, may not be suitable for the Moon formation, because
moonlets, building blocks of the Moon, of 100 m–100 km in radius may experience strong gas drag and fall onto
Earth on a short timescale, failing to grow further. This problem may be avoided if large moonlets (?100 km)
form very quickly by streaming instability, which is a process to concentrate particles enough to cause gravitational
collapse and rapid formation of planetesimals or moonlets. Here, we investigate the effect of the streaming
instability in the Moon-forming disk for the first time and find that this instability can quickly form ∼100 km-sized
moonlets. However, these moonlets are not large enough to avoid strong drag, and they still fall onto Earth quickly.
This suggests that the vapor-rich disks may not form the large Moon, and therefore the models that produce vaporpoor disks are supported. This result is applicable to general impact-induced moon-forming disks, supporting the
previous suggestion that small planets (<1.6 R⊕) are good candidates to host large moons because their impactinduced disks would likely be vapor-poor. We find a limited role of streaming instability in satellite formation in an
impact-induced disk, whereas it plays a key role during planet formation.
Unified Astronomy Thesaurus concepts: Earth-moon system (436)
Discovery of Merging Twin Quasars at z=6.05Sérgio Sacani
We report the discovery of two quasars at a redshift of z = 6.05 in the process of merging. They were
serendipitously discovered from the deep multiband imaging data collected by the Hyper Suprime-Cam (HSC)
Subaru Strategic Program survey. The quasars, HSC J121503.42−014858.7 (C1) and HSC J121503.55−014859.3
(C2), both have luminous (>1043 erg s−1
) Lyα emission with a clear broad component (full width at half
maximum >1000 km s−1
). The rest-frame ultraviolet (UV) absolute magnitudes are M1450 = − 23.106 ± 0.017
(C1) and −22.662 ± 0.024 (C2). Our crude estimates of the black hole masses provide log 8.1 0. ( ) M M BH = 3
in both sources. The two quasars are separated by 12 kpc in projected proper distance, bridged by a structure in the
rest-UV light suggesting that they are undergoing a merger. This pair is one of the most distant merging quasars
reported to date, providing crucial insight into galaxy and black hole build-up in the hierarchical structure
formation scenario. A companion paper will present the gas and dust properties captured by Atacama Large
Millimeter/submillimeter Array observations, which provide additional evidence for and detailed measurements of
the merger, and also demonstrate that the two sources are not gravitationally lensed images of a single quasar.
Unified Astronomy Thesaurus concepts: Double quasars (406); Quasars (1319); Reionization (1383); High-redshift
galaxies (734); Active galactic nuclei (16); Galaxy mergers (608); Supermassive black holes (1663)
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This document summarizes spectroscopic evidence from electronic absorption, magnetic circular dichroism (MCD), and resonance Raman spectroscopies that provide insight into the unique bonding interaction in oxo-molybdenum dithiolate complexes. The data suggests these complexes have low-energy sulfur to molybdenum charge transfer transitions originating from a set of four filled dithiolate orbitals that are primarily sulfur in character. Resonance Raman excitation profiles allowed assignment of an ene-dithiolate in-plane sulfur to molybdenum transition. Three totally symmetric vibrational modes were also identified. The results provide context for understanding electron transfer pathways in pyranopterin dithiolate centers
Effect of Concentration of Silver Nanoparticles on the Uptake of Silver from ...Agriculture Journal IJOEAR
— The bioavailability and uptake of silver from silver nanoparticles in soil was investigated. Two species of insects, Acheta domesticus and Tenebrio molitor, and two species of plants, Helianthus annuus and Sorghum vulgare, were exposed to a range of concentrations of silver nanoparticles in soil. Silver nanoparticles were charactrized by techniques including transmission electron microscopy, dynamic light scattering, and powder X-ray diffraction. The concentration of silver in insects and plants exposed to silver nanoparticles was measured using inductively coupled plasma-optical emission spectrometry. The results suggested an increase in the levels of silver in both insects and plants as a function of increasing concentrations of silver nanoparticles in soil. The translocation of silver to various parts of dicot plants such as stems and leaves was also observed. Such a result was not observed in the case of monocot plants. Results from this study suggests that silver nanoparticles would be available for uptake by insects and plants in terrestrial ecosystems.
Geochemistry involves studying the chemical composition of Earth and other planets, as well as the chemical processes that govern rocks, water, and soils. It examines how chemical elements are distributed and move through different parts of Earth over time. Key techniques for geochemical analysis include electron probe microanalysis and X-ray fluorescence spectrometry. Proper interpretation of geochemical data requires considering analytical uncertainty and discussing limitations with laboratory experts.
Hydrogen-bearing vesicles in space weathered lunar calcium-phosphatesSérgio Sacani
Water on the surface of the Moon is a potentially vital resource for future lunar bases and
longer-range space exploration. Effective use of the resource depends on developing an
understanding of where and how within the regolith the water is formed and retained. Solar
wind hydrogen, which can form molecular hydrogen, water and/or hydroxyl on the lunar
surface, reacts and is retained differently depending on regolith mineral content, thermal
history, and other variables. Here we present transmission electron microscopy analyses of
Apollo lunar soil 79221 that reveal solar-wind hydrogen concentrated in vesicles as molecular
hydrogen in the calcium-phosphates apatite and merrillite. The location of the vesicles in the
space weathered grain rims offers a clear link between the vesicle contents and solar wind
irradiation, as well as individual grain thermal histories. Hydrogen stored in grain rims is a
source for volatiles released in the exosphere during impacts.
The document describes a study that used a combination of particle induced x-ray emission (PIXE), Rutherford backscattering spectroscopy (RBS), and x-ray diffraction (XRD) to characterize pottery from the Epiclassic period in Teotihuacan, Mexico. PIXE and RBS were used to determine the elemental compositions of 19 pottery samples, while XRD identified the mineral phases present. The results showed that most pottery samples had similar compositions, but two samples had distinct elemental profiles, suggesting a different origin. The study provided information on pottery production and resources during the decline of the Teotihuacan civilization.
Prebiosignature Molecules Can Be Detected in Temperate Exoplanet Atmospheres ...Sérgio Sacani
The search for biosignatures on exoplanets connects the fields of biology and biochemistry to astronomical observation, with the hope that we might detect evidence of active biological processes on
worlds outside the solar system. Here we focus on a complementary aspect of exoplanet characterisation connecting astronomy to prebiotic chemistry: the search for molecules associated with the origin
of life, prebiosignatures. Prebiosignature surveys in planetary atmospheres offer the potential to both
constrain the ubiquity of life in the galaxy and provide important tests of current prebiotic syntheses
outside of the laboratory setting. Here, we quantify the minimum abundance of identified prebiosignature molecules that would be required for detection by transmission spectroscopy using JWST. We
consider prebiosignatures on five classes of terrestrial planet: an ocean planet, a volcanic planet, a
post-impact planet, a super-Earth, and an early Earth analogue. Using a novel modelling and detection test pipeline, with simulated JWST noise, we find the detection thresholds of hydrogen cyanide
(HCN), hydrogen sulfide (H2S), cyanoacetylene (HC3N), ammonia (NH3), methane (CH4), acetylene
(C2H2), sulfur dioxide (SO2), nitric oxide (NO), formaldehyde (CH2O), and carbon monoxide (CO) in
a variety of low mean molecular weight (< 5) atmospheres. We test the dependence of these detection
thresholds on M dwarf target star and the number of observed transits, finding that a modest number
of transits (1-10) are required to detect prebiosignatures in numerous candidate planets, including
TRAPPIST-1e with a high mean molecular weight atmosphere. We find that the NIRSpec G395M/H
instrument is best suited for detecting most prebiosignatures.
Volatile and organic_composition_of_sedimentary_rocks_in_yellowknife_bay_gale...Sérgio Sacani
This document summarizes the results of experiments analyzing the volatile and organic compositions of sedimentary rock samples from Yellowknife Bay in Gale Crater, Mars. The samples were obtained using the Curiosity rover's drill. Analysis found the samples released water, carbon dioxide, sulfur dioxide, oxygen, and other gases when heated. The water and oxygen releases suggest the presence of hydrated minerals like phyllosilicates and oxychlorine compounds. Small amounts of organic compounds, including chlorinated hydrocarbons, were also detected, though the carbon source is uncertain. The sediments appear to have preserved evidence of past environmental conditions and potential habitability in Yellowknife Bay.
This document summarizes a student research project on analyzing heavy metal contamination in the plant Celosia argentea collected from four different locations. The student describes collecting plant samples, using atomic absorption spectrometry to determine metal concentrations, and finding that levels of metals like iron, copper, zinc, manganese, and chromium were below permissible limits set by the FAO and WHO. However, the student notes that farming along roadsides should still be discouraged due to potential heavy metal pollution from vehicular traffic.
Synthesis of prebiotic organics from CO2 by catalysis with meteoritic and vo...Sérgio Sacani
The emergence of prebiotic organics was a mandatory step toward the origin of life. The signifcance
of the exogenous delivery versus the in-situ synthesis from atmospheric gases is still under debate.
We experimentally demonstrate that iron-rich meteoritic and volcanic particles activate and catalyse
the fxation of CO2, yielding the key precursors of life-building blocks. This catalysis is robust and
produces selectively aldehydes, alcohols, and hydrocarbons, independent of the redox state of the
environment. It is facilitated by common minerals and tolerates a broad range of the early planetary
conditions (150–300 °C, ≲ 10–50 bar, wet or dry climate). We fnd that up to 6 × 108 kg/year of prebiotic
organics could have been synthesized by this planetary-scale process from the atmospheric CO2 on
Hadean Earth.
This document analyzes the magnesium isotopic compositions of 47 lunar samples including mare basalts, highland rocks, regolith breccias, and lunar soils. The samples show a range of magnesium isotopic values from -0.61‰ to 0.02‰ in mare basalts and -0.34‰ to -0.18‰ in highland rocks. Limited variation is observed among lunar soils and breccias, but large fractionation is seen between low-Ti and high-Ti basalts. Overall, the Moon has a magnesium isotopic composition indistinguishable from Earth and chondrites, suggesting homogeneous distribution in the solar system without fractionation during the Moon-forming giant impact
Unique chemistry of a diamond-bearing pebble from the Libyan Desert Glass str...Carlos Bella
This document summarizes research on a unique black, shiny, and intensely fractured stone named "Hypatia" found in the Libyan Desert Glass strewnfield in southwest Egypt. Analysis showed the stone is composed primarily of amorphous carbonaceous matter containing nanodiamonds. Isotopic signatures of carbon and noble gases rule out a terrestrial origin and match cometary materials. The researchers propose Hypatia is a remnant of a comet nucleus fragment that was incorporated into the bolide that created the Libyan Desert Glass in an atmospheric airburst event 28.5 million years ago. Its shock transformation produced a weathering-resistant material that has been exceptionally preserved.
This document analyzes the magnesium isotopic compositions of 22 differentiated meteorites from 7 types of achondrites and pallasite meteorites. It finds:
1) Achondrites have d26Mg values ranging from -0.369‰ to -0.158‰, with most compositions similar and showing no significant isotopic fractionation.
2) However, some angrites and howardite-eucrite-diogenite (HED) meteorites have slightly heavier Mg isotopic compositions, possibly due to impact evaporation or higher clinopyroxene abundances.
3) The average Mg isotopic composition of achondrites (-0.246‰) is indistinguish
This document summarizes a study that uses geochemical modeling to constrain the possible composition of Europa's subsurface ocean and seafloor. The study models how seven different candidate bulk accretionary materials for Europa (various carbonaceous and ordinary chondrites) would alter through water-rock reactions. The models produce ocean compositions within 10% of previous estimates and indicate that precipitation of different mineral phases could depend on the rock type. Ordinary chondrites may produce higher calcium ion levels in Europa's present-day ocean compared to carbonaceous materials. Future missions could help determine Europa's actual accretionary material by detecting these mineral signatures or ocean chemistry.
1) The document describes an experiment where an ice mixture simulating interstellar medium composition was ultraviolet irradiated at 12K and analyzed after warming.
2) 16 amino acids were detected in the residue, including some that are also found in meteorites. Chiral amino acids showed enantiomeric separation.
3) The results demonstrate that amino acids can be spontaneously generated in interstellar ice analogs upon ultraviolet irradiation, supporting the hypothesis that amino acids could have been delivered to Earth by comets or meteorites.
The Primary Source of Mercury in the Subsoil and Environmental Impacts AJASTJournal
The paper aims to figure out the primary source of mercury in the subsoil and environmental impacts.
By using descriptive method for primary model, synthesis methods and process analysis and analysis of difficulties and discussion, The study of this problem point that, The primary source of mercury in the subsoil is considered to be deep exhalations coming from with the activation of deep processes - geothermal, eruptive, etc., and its intensive rocks enriched with organic matter become an accumulator in the sedimentary cover -carbonaceous formations and soil layer. It is from the latter that she again enters biocycle with a new stage of intravital accumulation in plant and animal organisms in the greater the amount, the higher its content in the environment. Moreover, it is also observed.
The Primary Source of Mercury in the Subsoil and Environmental Impacts IIJSRJournal
The paper aims to figure out the primary source of mercury in the subsoil and environmental impacts.
By using descriptive method for primary model, synthesis methods and process analysis and analysis of difficulties and discussion, The study of this problem point that, The primary source of mercury in the subsoil is considered to be deep exhalations coming from with the activation of deep processes - geothermal, eruptive, etc., and its intensive rocks enriched with organic matter become an accumulator in the sedimentary cover -carbonaceous formations and soil layer. It is from the latter that she again enters biocycle with a new stage of intravital accumulation in plant and animal organisms in the greater the amount, the higher its content in the environment. Moreover, it is also observed.
Rishav Prakash discusses heavy metal removal technologies. Trace amounts of heavy metals like copper, iron, and zinc are required by organisms, but excessive levels can be toxic. Sources of heavy metals include mining, agriculture, solid waste, automobiles, and fossil fuel emissions. Removal technologies discussed include reverse osmosis, precipitation, ion exchange, adsorption, and biosorption. Biosorption is the passive binding of heavy metals by inactive biomass like algae, fungi, and bacteria through mechanisms like adsorption, ion exchange, complexation, and precipitation. Obligate halophilic fungi like Aspergillus flavus and Sterigmatomyces halophilus show potential for biosorbing cadm
Iron acquisition and mineral transformation by cyanobacteria living in extrem...Sérgio Sacani
Iron is an essential micronutrient for most living organisms, including cyanobacteria. These microorganisms have
been found in Earth's driest polar and non-polar deserts, including the Atacama Desert, Chile. Iron-containing
minerals were identified in colonized rock substrates from the Atacama Desert, however, the interactions be-
tween microorganisms and iron minerals remain unclear. In the current study, we determined that colonized
gypsum rocks collected from the Atacama Desert contained both magnetite and hematite phases. A cyanobacteria
isolate was cultured on substrates consisting of gypsum with embedded magnetite nanoparticles. Transmission
electron microscopy imaging revealed a significant reduction in the size of magnetite nanoparticles due to their
dissolution, which occurred around the microbial biofilms. Concurrently, hematite was detected, likely from the
oxidation of the magnetite nanoparticles. Higher cell counts and production of siderophores were observed in
cultures with magnetite nanoparticles suggesting that cyanobacteria were actively acquiring iron from the
magnetite nanoparticles. Magnetite dissolution and iron acquisition by the cyanobacteria was further confirmed
using large bulk magnetite crystals, uncovering a survival strategy of cyanobacteria in these extreme
environments.
This study explores the petrography, chemistry, and cooling rates of the LL-chondrite meteorite LAR 12325 in order to understand its formation history. Petrographic analysis found the meteorite consists of clasts embedded in an impact melt matrix, indicating it experienced shock metamorphism from an asteroid impact. Chemical compositions of minerals in the clasts and melt are consistent with an LL-chondrite. Fast initial cooling rates of 27-247°C/s were estimated, but commonly used methods to estimate longer-term cooling rates do not apply to LL-chondrites with high metal nickel content. The parent asteroid underwent thermal metamorphism before being impacted, melted, and rapidly cooled
Similar to Abundant presolar grains and primordial organics preserved in carbon-rich exogenous clasts in asteroid Ryugu (20)
The Limited Role of the Streaming Instability during Moon and Exomoon FormationSérgio Sacani
It is generally accepted that the Moon accreted from the disk formed by an impact between the proto-Earth and
impactor, but its details are highly debated. Some models suggest that a Mars-sized impactor formed a silicate
melt-rich (vapor-poor) disk around Earth, whereas other models suggest that a highly energetic impact produced a
silicate vapor-rich disk. Such a vapor-rich disk, however, may not be suitable for the Moon formation, because
moonlets, building blocks of the Moon, of 100 m–100 km in radius may experience strong gas drag and fall onto
Earth on a short timescale, failing to grow further. This problem may be avoided if large moonlets (?100 km)
form very quickly by streaming instability, which is a process to concentrate particles enough to cause gravitational
collapse and rapid formation of planetesimals or moonlets. Here, we investigate the effect of the streaming
instability in the Moon-forming disk for the first time and find that this instability can quickly form ∼100 km-sized
moonlets. However, these moonlets are not large enough to avoid strong drag, and they still fall onto Earth quickly.
This suggests that the vapor-rich disks may not form the large Moon, and therefore the models that produce vaporpoor disks are supported. This result is applicable to general impact-induced moon-forming disks, supporting the
previous suggestion that small planets (<1.6 R⊕) are good candidates to host large moons because their impactinduced disks would likely be vapor-poor. We find a limited role of streaming instability in satellite formation in an
impact-induced disk, whereas it plays a key role during planet formation.
Unified Astronomy Thesaurus concepts: Earth-moon system (436)
Discovery of Merging Twin Quasars at z=6.05Sérgio Sacani
We report the discovery of two quasars at a redshift of z = 6.05 in the process of merging. They were
serendipitously discovered from the deep multiband imaging data collected by the Hyper Suprime-Cam (HSC)
Subaru Strategic Program survey. The quasars, HSC J121503.42−014858.7 (C1) and HSC J121503.55−014859.3
(C2), both have luminous (>1043 erg s−1
) Lyα emission with a clear broad component (full width at half
maximum >1000 km s−1
). The rest-frame ultraviolet (UV) absolute magnitudes are M1450 = − 23.106 ± 0.017
(C1) and −22.662 ± 0.024 (C2). Our crude estimates of the black hole masses provide log 8.1 0. ( ) M M BH = 3
in both sources. The two quasars are separated by 12 kpc in projected proper distance, bridged by a structure in the
rest-UV light suggesting that they are undergoing a merger. This pair is one of the most distant merging quasars
reported to date, providing crucial insight into galaxy and black hole build-up in the hierarchical structure
formation scenario. A companion paper will present the gas and dust properties captured by Atacama Large
Millimeter/submillimeter Array observations, which provide additional evidence for and detailed measurements of
the merger, and also demonstrate that the two sources are not gravitationally lensed images of a single quasar.
Unified Astronomy Thesaurus concepts: Double quasars (406); Quasars (1319); Reionization (1383); High-redshift
galaxies (734); Active galactic nuclei (16); Galaxy mergers (608); Supermassive black holes (1663)
Mapping the Growth of Supermassive Black Holes as a Function of Galaxy Stella...Sérgio Sacani
The growth of supermassive black holes is strongly linked to their galaxies. It has been shown that the population
mean black hole accretion rate (BHAR) primarily correlates with the galaxy stellar mass (Må) and redshift for the
general galaxy population. This work aims to provide the best measurements of BHAR as a function of Må and
redshift over ranges of 109.5 < Må < 1012 Me and z < 4. We compile an unprecedentedly large sample with 8000
active galactic nuclei (AGNs) and 1.3 million normal galaxies from nine high-quality survey fields following a
wedding cake design. We further develop a semiparametric Bayesian method that can reasonably estimate BHAR
and the corresponding uncertainties, even for sparsely populated regions in the parameter space. BHAR is
constrained by X-ray surveys sampling the AGN accretion power and UV-to-infrared multiwavelength surveys
sampling the galaxy population. Our results can independently predict the X-ray luminosity function (XLF) from
the galaxy stellar mass function (SMF), and the prediction is consistent with the observed XLF. We also try adding
external constraints from the observed SMF and XLF. We further measure BHAR for star-forming and quiescent
galaxies and show that star-forming BHAR is generally larger than or at least comparable to the quiescent BHAR.
Unified Astronomy Thesaurus concepts: Supermassive black holes (1663); X-ray active galactic nuclei (2035);
Galaxies (573)
Compositions of iron-meteorite parent bodies constrainthe structure of the pr...Sérgio Sacani
Magmatic iron-meteorite parent bodies are the earliest planetesimals in the Solar System,and they preserve information about conditions and planet-forming processes in thesolar nebula. In this study, we include comprehensive elemental compositions andfractional-crystallization modeling for iron meteorites from the cores of five differenti-ated asteroids from the inner Solar System. Together with previous results of metalliccores from the outer Solar System, we conclude that asteroidal cores from the outerSolar System have smaller sizes, elevated siderophile-element abundances, and simplercrystallization processes than those from the inner Solar System. These differences arerelated to the formation locations of the parent asteroids because the solar protoplane-tary disk varied in redox conditions, elemental distributions, and dynamics at differentheliocentric distances. Using highly siderophile-element data from iron meteorites, wereconstruct the distribution of calcium-aluminum-rich inclusions (CAIs) across theprotoplanetary disk within the first million years of Solar-System history. CAIs, the firstsolids to condense in the Solar System, formed close to the Sun. They were, however,concentrated within the outer disk and depleted within the inner disk. Future modelsof the structure and evolution of the protoplanetary disk should account for this dis-tribution pattern of CAIs.
Signatures of wave erosion in Titan’s coastsSérgio Sacani
The shorelines of Titan’s hydrocarbon seas trace flooded erosional landforms such as river valleys; however, it isunclear whether coastal erosion has subsequently altered these shorelines. Spacecraft observations and theo-retical models suggest that wind may cause waves to form on Titan’s seas, potentially driving coastal erosion,but the observational evidence of waves is indirect, and the processes affecting shoreline evolution on Titanremain unknown. No widely accepted framework exists for using shoreline morphology to quantitatively dis-cern coastal erosion mechanisms, even on Earth, where the dominant mechanisms are known. We combinelandscape evolution models with measurements of shoreline shape on Earth to characterize how differentcoastal erosion mechanisms affect shoreline morphology. Applying this framework to Titan, we find that theshorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded bywaves, rather than a uniform erosional process or no coastal erosion, particularly if wave growth saturates atfetch lengths of tens of kilometers.
SDSS1335+0728: The awakening of a ∼ 106M⊙ black hole⋆Sérgio Sacani
Context. The early-type galaxy SDSS J133519.91+072807.4 (hereafter SDSS1335+0728), which had exhibited no prior optical variations during the preceding two decades, began showing significant nuclear variability in the Zwicky Transient Facility (ZTF) alert stream from December 2019 (as ZTF19acnskyy). This variability behaviour, coupled with the host-galaxy properties, suggests that SDSS1335+0728 hosts a ∼ 106M⊙ black hole (BH) that is currently in the process of ‘turning on’. Aims. We present a multi-wavelength photometric analysis and spectroscopic follow-up performed with the aim of better understanding the origin of the nuclear variations detected in SDSS1335+0728. Methods. We used archival photometry (from WISE, 2MASS, SDSS, GALEX, eROSITA) and spectroscopic data (from SDSS and LAMOST) to study the state of SDSS1335+0728 prior to December 2019, and new observations from Swift, SOAR/Goodman, VLT/X-shooter, and Keck/LRIS taken after its turn-on to characterise its current state. We analysed the variability of SDSS1335+0728 in the X-ray/UV/optical/mid-infrared range, modelled its spectral energy distribution prior to and after December 2019, and studied the evolution of its UV/optical spectra. Results. From our multi-wavelength photometric analysis, we find that: (a) since 2021, the UV flux (from Swift/UVOT observations) is four times brighter than the flux reported by GALEX in 2004; (b) since June 2022, the mid-infrared flux has risen more than two times, and the W1−W2 WISE colour has become redder; and (c) since February 2024, the source has begun showing X-ray emission. From our spectroscopic follow-up, we see that (i) the narrow emission line ratios are now consistent with a more energetic ionising continuum; (ii) broad emission lines are not detected; and (iii) the [OIII] line increased its flux ∼ 3.6 years after the first ZTF alert, which implies a relatively compact narrow-line-emitting region. Conclusions. We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 106M⊙ AGN that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGNobserved in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour. Key words. galaxies: active– accretion, accretion discs– galaxies: individual: SDSS J133519.91+072807.4
Discovery of An Apparent Red, High-Velocity Type Ia Supernova at 𝐳 = 2.9 wi...Sérgio Sacani
We present the JWST discovery of SN 2023adsy, a transient object located in a host galaxy JADES-GS
+
53.13485
−
27.82088
with a host spectroscopic redshift of
2.903
±
0.007
. The transient was identified in deep James Webb Space Telescope (JWST)/NIRCam imaging from the JWST Advanced Deep Extragalactic Survey (JADES) program. Photometric and spectroscopic followup with NIRCam and NIRSpec, respectively, confirm the redshift and yield UV-NIR light-curve, NIR color, and spectroscopic information all consistent with a Type Ia classification. Despite its classification as a likely SN Ia, SN 2023adsy is both fairly red (
�
(
�
−
�
)
∼
0.9
) despite a host galaxy with low-extinction and has a high Ca II velocity (
19
,
000
±
2
,
000
km/s) compared to the general population of SNe Ia. While these characteristics are consistent with some Ca-rich SNe Ia, particularly SN 2016hnk, SN 2023adsy is intrinsically brighter than the low-
�
Ca-rich population. Although such an object is too red for any low-
�
cosmological sample, we apply a fiducial standardization approach to SN 2023adsy and find that the SN 2023adsy luminosity distance measurement is in excellent agreement (
≲
1
�
) with
Λ
CDM. Therefore unlike low-
�
Ca-rich SNe Ia, SN 2023adsy is standardizable and gives no indication that SN Ia standardized luminosities change significantly with redshift. A larger sample of distant SNe Ia is required to determine if SN Ia population characteristics at high-
�
truly diverge from their low-
�
counterparts, and to confirm that standardized luminosities nevertheless remain constant with redshift.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
BIRDS DIVERSITY OF SOOTEA BISWANATH ASSAM.ppt.pptxgoluk9330
Ahota Beel, nestled in Sootea Biswanath Assam , is celebrated for its extraordinary diversity of bird species. This wetland sanctuary supports a myriad of avian residents and migrants alike. Visitors can admire the elegant flights of migratory species such as the Northern Pintail and Eurasian Wigeon, alongside resident birds including the Asian Openbill and Pheasant-tailed Jacana. With its tranquil scenery and varied habitats, Ahota Beel offers a perfect haven for birdwatchers to appreciate and study the vibrant birdlife that thrives in this natural refuge.
Evaluation and Identification of J'BaFofi the Giant Spider of Congo and Moke...MrSproy
ABSTRACT
The J'BaFofi, or "Giant Spider," is a mainly legendary arachnid by reportedly inhabiting the dense rain forests of
the Congo. As despite numerous anecdotal accounts and cultural references, the scientific validation remains more elusive.
My study aims to proper evaluate the existence of the J'BaFofi through the analysis of historical reports,indigenous
testimonies and modern exploration efforts.
Embracing Deep Variability For Reproducibility and Replicability
Abstract: Reproducibility (aka determinism in some cases) constitutes a fundamental aspect in various fields of computer science, such as floating-point computations in numerical analysis and simulation, concurrency models in parallelism, reproducible builds for third parties integration and packaging, and containerization for execution environments. These concepts, while pervasive across diverse concerns, often exhibit intricate inter-dependencies, making it challenging to achieve a comprehensive understanding. In this short and vision paper we delve into the application of software engineering techniques, specifically variability management, to systematically identify and explicit points of variability that may give rise to reproducibility issues (eg language, libraries, compiler, virtual machine, OS, environment variables, etc). The primary objectives are: i) gaining insights into the variability layers and their possible interactions, ii) capturing and documenting configurations for the sake of reproducibility, and iii) exploring diverse configurations to replicate, and hence validate and ensure the robustness of results. By adopting these methodologies, we aim to address the complexities associated with reproducibility and replicability in modern software systems and environments, facilitating a more comprehensive and nuanced perspective on these critical aspects.
https://hal.science/hal-04582287
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
Rodents, Birds and locust_Pests of crops.pdfPirithiRaju
Mole rat or Lesser bandicoot rat, Bandicotabengalensis
•Head -round and broad muzzle
•Tail -shorter than head, body
•Prefers damp areas
•Burrows with scooped soil before entrance
•Potential rat, one pair can produce more than 800 offspringsin one year
Hariyalikart Case Study of helping farmers in Biharrajsaurav589
Helping farmers all across India through our latest technologies of modern farming like drones for irrigation and best pest control For more visit : https://www.hariyalikart.com/case-study
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
2. processing appears to decrease or destroy isotopic anomalies, par-
ticularly those in H, in IOM, but the effects are complicated and
poorly understood (15). To investigate Ryugu’s origin, history,
and extent of aqueous alteration and thermal metamorphism, we
determined the abundances and isotopic, chemical, and mineralog-
ical characteristics of presolar grains and isotopically anomalous
organic matter (IAOM) within various lithologies.
RESULTS
The elemental compositions of fragments of Ryugu particles C0002
and A0040 were determined by field-emission scanning electron
microscopy and energy-dispersive x-ray spectroscopy (FE-SEM-
EDX), revealing a phyllosilicate-dominated CI-like matrix enclos-
ing S- and Fe-rich and Mg- and Si-poor clasts. These clasts were
present as discrete regions having well-defined boundaries with
the hydrated matrix (clasts 1 to 3, ~50 to 100 μm in size) (Figs. 1
and 2 and figs. S1 and S3) and as more diffuse regions where the
boundaries between the clast and host matrix were less clear
(clasts 4 and 5, ~50 to 200 μm in size) (fig. S2). The matrix of chon-
dritic samples is the fine-grained groundmass between more coarse
objects such as chondrules. It consists predominantly of silicates
that may be crystalline, amorphous, anhydrous, or hydrated, and
it also contains organic matter. It is within this matrix that most
presolar grains are found. Presolar grains and IAOM were identified
in interclast matrix and five clasts (e.g., Fig. 2 and figs. S3 and S4) by
C, N, O, and Si isotopic mapping using nanoscale secondary ion
mass spectrometry (NanoSIMS).
A total of 58 C-rich presolar grains were identified. Fifty grains
were 13
C-rich, and 8 were 13
C-poor (fig. S5 and table S1). Most of
these grains likely condensed around solar to lower-than-solar met-
allicity asymptotic giant branch (AGB) stars, and some grains have
supernova signatures (7). On the basis of the NanoSIMS 28
Si−
/12
C−
ratios, 47 of the grains were silicon carbide (SiC) and 11 were graph-
ite. The mineralogical and chemical characterization of 13
C-rich
grain C0002-C11 (table S1) from clast 1 by scanning transmission
electron microscopy (STEM) indicated a polycrystalline SiC with
multiple 20- to 50-nm–sized subgrains, some of which showed
unit cell–scale twinning (fig. S6). The structure was consistent
with cubic 3C β-SiC, the most common polytype. This grain had
a partially oxidized rim likely resulting from secondary alteration.
Clast 1 in C0002 (Fig. 1) also contained two highly 17
O-rich
grains of likely AGB star origin and one 18
O-rich supernova grain
(Fig. 2, figs. S3 and S5, and table S1). STEM analysis of
17
O-rich grain C0002-C3 in clast 1 confirmed that it is a Mg-, Fe-,
and Al-bearing silicate (Fig. 3) with pyroxene stoichiometry
[(Mg0.8Fe0.2)(Si, Al)O3]. Diffraction data from the grain showed
diffuse scattering, consistent with an amorphous structure. The
stoichiometric chemical composition suggests that the grain
condensed as a crystal in the parent circumstellar environment
and was later amorphized, likely by irradiation in space. Presolar
grains C0002-C1 and C0002-C2 had NanoSIMS 28
Si−
/16
O−
and
24
Mg16
O−
/16
O−
ratios similar to C0002-C3 (table S1), implying that
they are also silicates.
The abundances of presolar grains in the different analyzed
clasts and matrix regions are given in table S2 and shown in fig.
S7. The presolar silicate abundance in clast 1 is 104þ102
57 parts per
million (ppm) (1σ), and the upper abundances in the other lithol-
ogies are <18 ppm. Clasts 1 and 2 have similarly high abundances of
presolar SiC, 277þ127
91 and 219þ70
54 ppm, respectively, whereas the
other analyzed lithologies had abundances <73 ppm. Presolar
graphite abundances for all analyzed lithologies were <38 ppm.
A total of 433, mainly submicrometer-sized grains showed N iso-
topic anomalies and low 28
Si−
/12
C−
ratios, suggestive of organic
matter (table S3, Fig. 4, and fig. S8). Both 15
N enrichments (δ15
N
~ +200 to +3200‰) and depletions (δ15
N ~ −170 to −500‰)
1
Astromaterials Research and Exploration Science, NASA Johnson Space Center, Houston, TX 77058, USA. 2
Universities Space Research Association, Lunar and Planetary
Institute, Houston, TX 77058, USA. 3
Centre de Recherches Pétrographiques et Géochimiques, CNRS - Université de Lorraine, Nancy 54500, France. 4
Graduate School of
Engineering Materials Science and Engineering, Tokyo Denki University, Tokyo 120-8551, Japan. 5
Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie,
Sorbonne Université, Museum National d’Histoire Naturelle, CNRS UMR 7590, IRD, Paris 75005, France. 6
Earth and Planets Laboratory, Carnegie Institution for Science,
Washington, DC 20015, USA. 7
McDonnell Center for the Space Sciences and Physics Department, Washington University, St. Louis, MO 63130, USA. 8
Geochemical Re-
search Center, The University of Tokyo, Tokyo 113-0033, Japan. 9
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, GD 510640, China.
10
Department of Natural History Sciences, IIL, Hokkaido University, Sapporo 001-0021, Japan. 11
Centre for Star and Planet Formation, GLOBE Institute, University of Co-
penhagen, Copenhagen K 1350, Denmark. 12
Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth 95447, Germany. 13
Université Paris Cités, Institut de physique du
globe de Paris, CNRS, Paris 75005, France. 14
Department of Earth Science Education, Seoul National University, Seoul 08826, Republic of Korea. 15
Department of the
Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA. 16
Faculty of Geosciences and Geography,
University of Göttingen, Göttingen D-37077, Germany. 17
Faculty of Science, Ibaraki University, Mito 310-8512, Japan. 18
Institute of Space and Astronautical Science, Japan
Aerospace Exploration Agency, Sagamihara 252-5210, Japan. 19
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan.
20
General Systems Studies, The University of Tokyo, Tokyo 153-0041, Japan. 21
Earth and Planetary Sciences, Nagoya University, Nagoya 464-8601, Japan. 22
Osaka Appli-
cation Laboratory, SBUWDX, Rigaku Corporation, Osaka 569-1146, Japan. 23
Max Planck Institute for Chemistry, Mainz 55128, Germany. 24
Hawai‘i Institute of Geophysics
and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA. 25
Analytical Technology, Horiba Techno Service Co. Ltd., Kyoto 601-8125, Japan. 26
Earth and
Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan. 27
School of Earth and Environmental Sciences, The University of Queensland, St. Lucia, QLD 4072,
Australia. 28
Earth and Planetary Sciences, Kyoto University, Kyoto 606-8502, Japan. 29
Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706,
USA. 30
Max Planck Institute for Solar System Research, Göttingen 37077, Germany. 31
Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095, USA. 32
Thermal
Analysis, Rigaku Corporation, Tokyo 196-8666, Japan. 33
Applied Chemistry, Tokyo University of Science, Tokyo 162-8601, Japan. 34
Department of Space Studies, South-
west Research Institute, Boulder, CO 80302, USA. 35
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA. 36
Earth System Sciences, Korea
Polar Research Institute, Incheon 21990, Korea. 37
CAS Key Laboratory of Crust-Mantle Materials and Environments, University of Science and Technology of China, School
of Earth and Space Sciences, Anhui 230026, China. 38
Department of Earth Sciences, Natural History Museum, London SW7 5BD, UK. 39
Isotope Imaging Laboratory, Creative
Research Institution, Hokkaido University, Sapporo 001-0021, Japan. 40
Institute for Geochemistry and Petrology, Department of Earth Sciences, ETH Zurich, Zurich, Swit-
zerland. 41
Earth and Space Science, Osaka University, Osaka 560-0043, Japan. 42
Spectroscopy and Imaging, Japan Synchrotron Radiation Research Institute, Hyogo 679-
5198, Japan. 43
Department of Geology, University of Maryland, College Park, MD 20742, USA. 44
Graduate School of Natural Science and Technology, Okayama University,
Okayama 700-8530, Japan. 45
Earth and Planetary Sciences, University of California, Davis, Davis, CA 95616, USA. 46
Science and Engineering, National Museum of Nature
and Science, Tsukuba 305-0005, Japan. 47
Department of Chemistry, Tokyo University of Science, Tokyo 162-8601, Japan. 48
School of Earth Sciences and Engineering,
Nanjing University, Nanjing 210023, China. 49
Department of Earth Science, Tohoku University, Sendai 980-8578, Japan. 50
Department of Earth and Planetary Sciences,
Kyushu University, Fukuoka 819-0395, Japan. 51
Earth and Planetary Systems Science Program, Hiroshima University, Higashi-Hiroshima 739-8526, Japan. 52
Kanagawa
Institute of Technology, Atsugi 243-0292, Japan. 53
UTokyo Organization for Planetary and Space Science, University of Tokyo, Tokyo 113-0033, Japan.
*Corresponding author. Email: lan-anh.n.nguyen@nasa.gov
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3. were observed. Eleven percent of these grains had moderate C iso-
topic anomalies (δ13
C ranging from ±250‰). Of the grains having
C isotopic anomalies, 60% were enriched in 15
N. Three grains had
anomalous C isotopic compositions and isotopically normal N
compositions. The range of N and C isotopic compositions associ-
ated with organic matter was similar among the Ryugu lithologies.
We analyzed one grain from clast 1 having 220 and 240‰ deple-
tions in 13
C and 15
N, respectively, by TEM (fig. S9). The 300-nm–
sized amorphous grain contained C, N, O, and S, likely associated
with N-based and carbonyl (C=O) functionality and an organo-S
component, confirming that the grain is organic and not graphitic.
These results imply that other grains having moderately anomalous
C isotopic compositions and low 28
Si−
/12
C−
ratios are also organic.
DISCUSSION
Distribution of presolar grains
Presolar silicate grains are rapidly destroyed by aqueous alteration
and are only preserved in very primitive samples (9). For example,
presolar silicates have yet to be identified in the highly aqueously
altered CI chondrites, and the highest reported abundances occur
in anhydrous IDPs that are believed to have cometary origins
[e.g., (21)]. We identified presolar silicates only in C0002 clast 1
at an abundance of 104þ102
57 ppm (1σ; Fig. 5 and table S2). In
another study of Ryugu, a clast less-altered than bulk Ryugu had
a presolar silicate abundance of 25þ33
16 ppm (22). For the Ryugu
matrix and clasts 3 to 5, we determined a 1σ upper abundance
limit for presolar O-rich grains of 3 ppm. This upper limit is con-
sistent with abundances in another study of Ryugu [5þ5
3 ppm; (22)],
the upper limit for the CI chondrite Ivuna [4 ppm; (22)], and aque-
ously altered samples of all chondrite classes (9). More than 50% of
the Ryugu matrix is composed of phyllosilicates (2), and the
aqueous alteration that produced the hydrated matrix very likely de-
stroyed presolar silicate grains.
The preservation of presolar silicates in clast 1 indicates that it is
less altered than the host Ryugu matrix, in agreement with our TEM
observations showing that clast 1 is dominated by amorphous sili-
cates and GEMS (glass with embedded metal and sulfide)–like
grains, with minor phyllosilicates, sulfides, rare magnetite, C nano-
globules, and forsterite (fig. S10). These constituents resemble those
in the least altered fragments found by (3) in Ryugu. The matrix of
clast 1 is most similar to the matrices of weakly altered CR2
(Renazzo-type) chondrites [e.g., QUE 99177, MET 00426; (23,
24)]. The presolar silicate abundance in clast 1 is comparable to
those in less altered CRs, CO3s (Ornans-type), and ungrouped
chondrites (9) but is also within error of the highest reported abun-
dance in chondrite matrices (~240 ± 30 ppm in CO3 DOM 08006)
(Fig. 5) (19, 25). The range of abundances observed in chondrite
matrices is attributed to parent body aqueous alteration. While all
asteroids experienced some degree of parent body alteration, comets
remain largely unaltered since their formation in the cold outer
solar system. The abundance of presolar silicates in comet Wild 2
samples was estimated to be 600 to 830 ppm (26). Anhydrous
IDPs and some AMMs have characteristics that suggest cometary
origins. Reported presolar silicate abundances in anhydrous IDPs
vary widely, ranging from 140þ320
120 ppm (27) to 15; 000þ8170
5590 ppm
(21). A subset of IDPs proposed to be “isotopically primitive” has
an average abundance of 375 ppm (28), and the area-weighted
average for all measured anhydrous IDPs is 400 ppm (29). A
similar abundance of 360þ200
130 ppm was determined for a C-rich
cometary clast found in the CR2 chondrite LAP 02342 (30). The
highest abundance reported for AMMs is 170þ58
45 ppm (31). The
abundance of presolar silicates in clast 1 is lower than that of
comet Wild 2 but is consistent with abundances in some AMMs
and IDPs of probable cometary origin.
Unlike presolar silicates, presolar SiC and graphite grains survive
aqueous alteration but are destroyed by thermal metamorphism or
prolonged oxidation (10, 32, 33). Their abundances are relatively
consistent across unheated chondrite classes and types: ~30 ppm
for presolar SiC and <10 ppm for presolar graphite (10, 32, 33). A
presolar graphite abundance has not been reported for comet Wild
2, but the presolar SiC abundance was inferred to be 45 ppm (26),
consistent with chondrites. Only four presolar SiC have been iden-
tified in anhydrous IDPs, and estimated abundances range from 60
to 190 ppm (27, 34, 35). The average presolar SiC abundance in
AMMs is 14þ11
7 ppm (31). Presolar graphite grains have not been
identified in IDPs and AMMs. No presolar SiC or graphite was
found in the C-rich cometary clast (30). We found clasts 1 and 2
to have exceptional presolar SiC abundances, 277þ127
91 ppm (9
grains) and 219þ70
54 ppm (16 grains), respectively, whereas the
other Ryugu lithologies have abundances <73 ppm (table S2 and
fig. S7). The combined presolar SiC abundance of 45þ12
10 ppm in
Ryugu, excluding clasts 1 and 2, is consistent with abundances in
many unheated chondrites (Fig. 5) (10). The presolar graphite
abundances across Ryugu lithologies are more consistent, and the
average of 12þ6
4 ppm agrees with the ~10-ppm abundance in CI
chondrites Orgueil and Ivuna (22, 33). The similar presolar SiC
Fig. 1. Backscattered electron (BSE) image and elemental maps of a region of
grain C0002 containing primitive clast 1, outlined in the BSE image. This clast
is rich in Fe and S and depleted in Mg, Si, and O compared to the surrounding
matrix. It also contains Mg-rich silicate grains that are likely olivine. White arrows
indicate a cluster of these grains.
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4. and graphite abundances in Ryugu (excluding clasts 1 and 2) and CI
and unheated chondrites indicate that the Ryugu samples escaped
thermal metamorphism and prolonged oxidation. This agrees with
analyses of water in phyllosilicates in Ryugu samples that indicate
that Ryugu was never heated above 100°C (1). The Ryugu matrix,
therefore, accreted in a region of the protoplanetary disk that had
an abundance of presolar grains typically observed in chondritic
meteorite matrices.
The much higher presolar SiC abundances in clasts 1 and 2,
however, indicate that they accreted in a reservoir that was distinct
from Ryugu, comet Wild 2, and most chondrites, AMMs, and IDPs.
Elevated presolar SiC abundances have only been reported for two
CR2 chondrites: 160 ± 57 ppm in NWA 852 and 182 ± 34 ppm
(120þ28
23 ppm excluding a large grain) in GRV 021710 (Fig. 5) (36,
37). These abundances are similar to those in some anhydrous IDPs.
Relative to chondritic meteorites, some IDPs and AMMs show ele-
vated abundances of O-rich supernova stardust having large enrich-
ments in 18
O [e.g., (21, 31)], suggesting a heterogeneous
distribution of supernova dust in the protoplanetary disk. Most of
the presolar SiC grains in clasts 1 and 2 derive from C-rich AGB
stars and have C, N, and Si isotopic compositions falling within
the mainstream-, Y-, and Z-type classifications for SiC from AGB
stars (fig. S5) (7). Differences in nucleosynthetic isotopic anomalies
in noncarbonaceous and carbonaceous reservoirs have been linked
to the heterogeneous distribution of presolar grains in the solar pro-
toplanetary disk (38). The observed nucleosynthetic signatures
Fig. 2. Region of grain C0002 containing a portion of primitive clast 1 and hydrated Ryugu matrix. The BSE (top left) and corresponding NanoSIMS 16
O, 28
Si,
24
Mg16
O, 12
C, and 12
C14
N ion images show that the clast 1 matrix is more fine-grained and has a well-defined boundary with the altered Ryugu matrix. The NanoSIMS
ion images show that the clast has lower 28
Si signal and greater 12
C and 12
C14
N signals relative to the neighboring matrix, indicative of a higher abundance of N-rich
organic matter in the clast. The 12
C14
N image was acquired in a subsequent measurement, and the analysis region is shifted up by 3 μm relative to the other images. This
portion of clast 1 contains 17
O-rich presolar silicate C0002-C1 and 13
C-rich presolar SiC grain C0002-C7, shown by the arrows in the NanoSIMS δ17
O/16
O and δ13
C/12
C ratio
images. Isotope ratios are given as deviations from the standard values in per mil (‰). Small variations in the isotope ratio images are due to statistical fluctuations.
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5. require dust contributions from both supernova and AGB stars (38,
39). The inventory of refractory presolar grains in IDPs, AMMs, and
clasts 1 and 2 in Ryugu samples also points to heterogeneous distri-
butions of stardust from multiple stellar sources in the early
solar system.
While we did not find any presolar oxide grains in our study, (22)
found one grain in the Ryugu matrix for an abundance of 0.6 ppm.
From our study, the presolar SiC abundance in the primitive clasts is
~5.5 times greater than in the Ryugu matrix. If presolar oxides are
enriched to the same degree in the clasts, then the abundance would
be 3.2 ppm. Given the measured area of the clasts and using the
average presolar oxide size of 250 nm, we would expect to find
<0.3 presolar oxides in each clast. The probability of finding a pre-
solar oxide can also be calculated using the equation (1−e−A/B
) ×
100 (%), where A is the area analyzed in each clast and B is the
area analyzed by (22) to find one grain divided by 5.5 to represent
the enhanced abundance in the clasts. The probabilities of finding a
presolar oxide in clasts 1 and 2 are 21 and 50%, respectively. There-
fore, our results are not inconsistent with an enrichment in presolar
oxides relative to the Ryugu hydrated matrix.
Isotopically anomalous organic matter
Clasts 1 and 2 show greater abundances of organic matter than bulk
Ryugu based on the ~5 times higher NanoSIMS 12
C14
N/28
Si ratios.
This is similar to C-rich anhydrous IDPs and ultracarbonaceous
AMMs (UCAMMs) that have C contents >2 × CI (40, 41) and the
cometary clast found in LAP 02342 (30). Clasts 1 and 2 also contain
higher abundances of IAOM with N isotopic anomalies, 1.4 and
1.1%, respectively, compared to 0.07 and 0.3% in the C0002 and
A0040 matrix, respectively (Fig. 4). Only a few anhydrous IDPs
(34) and the CR2 chondrite EET 92042 (13) show percent level
or higher abundances of IAOM. The high C and N contents of clasts
1 and 2 relative to the Ryugu matrix can be seen in the NanoSIMS
isotope maps (Fig. 2 and fig. S3). The average NanoSIMS
12
C14
N/12
C ratios of IAOM in clasts 1 and 2 are 1.0 and 0.6, respec-
tively, while in the matrix of C0002 and A0040, they are 0.3 and 0.5,
respectively. The correlation between the abundance of N isotopic
anomalies and 12
C14
N/12
C ratio suggests that the N anomalies are
mainly carried by N-rich organic matter. IAOM in some anhydrous
IDPs is also strongly N-rich (14). The bulk 12
C14
N/12
C ratios for the
clasts and matrix are similar to the average ratios of the respective
IAOM. Therefore, the organic matter in the clasts is intrinsically
about two times more N-rich than organic matter in the Ryugu
matrix. Organic matter in comet Wild 2 and some UCAMMs
have higher N contents than chondrites and IDPs (41, 42). It has
been proposed that the organic matter in the UCAMMs formed
by chemical reactions of N- and methane-rich ices beyond the
trans-Neptunian region of the solar system (41). The organic
matter in the clasts likely also formed in the outer solar system.
We found clasts 1 and 2 to have remarkably high abundances of
IAOM having C isotopic anomalies—0.3 and 0.2%, respectively—
compared to 0.02% in the Ryugu matrix. Such rare C-anomalous
organic grains have only been identified in three CR2 chondrites
(13, 18, 43) and some anhydrous IDPs (12, 20, 28, 44). Their abun-
dance in the minimally altered CR2 chondrites QUE 99177 and
MET 00426 (~0.012%) led (18) to suggest that aqueous alteration
destroys the carriers of the C isotopic anomalies. However, the hy-
drated Ryugu matrix contains a similar abundance of C-anomalous
IAOM as the CR2 chondrites, and the overall abundance of IAOM
with N anomalies (0.17%) in the Ryugu matrix is comparable to
chondritic IOM [0.005 to 1%; (13)] and anhydrous IDPs [0.08%;
(28)]. The range of N isotopic ratios in the Ryugu IAOM also
rivals those in primitive chondrites (13, 18, 43), anhydrous IDPs
(21, 28, 44), C-rich AMMs (41), and comet Wild 2 (45, 46), with
the most extreme isotopic hotspot in hydrated Ryugu (δ15
N ~
3200‰) exceeding those in pristine samples. These observations
suggest that aqueous alteration does not erase or dilute the N and
C isotopic signatures of IAOM, similar to previous studies of chon-
dritic IOM residues [e.g., (47)]. The similar abundances and com-
positions of IAOM suggest that the parent bodies of Ryugu and
some CR chondrites and anhydrous IDPs accreted common pri-
mordial organic matter.
That the organic matter in clasts 1 and 2 shows higher N con-
tents, higher abundances of N isotopic anomalies, and the highest
abundance of C-anomalous IAOM ever reported implies that the
accreted IAOM formed in a region of the cold molecular cloud
Fig. 3. NanoSIMS and TEM data for the 17
O-rich presolar grain C0002-C3.
The presolar grain is indicated by the arrow in the 17
O/16
O ratio image of a
region of clast 1 (top left). Isotopic ratios are given as deviations from terrestrial
composition in per mil (‰). The inset in the high-resolution TEM (HR-TEM)
image shows diffuse scattering consistent with an amorphous structure. The
bright-field STEM (BF-STEM) image and elemental maps of the presolar grain
(outlined in red) show that it is a silicate with pyroxene stoichiometry and com-
position (Mg0.8Fe0.2)(Si, Al)O3.
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6. distinct from the formation region of IAOM in bulk Ryugu and
known chondritic materials. Theoretical models of gas-phase ion-
molecule reactions in dense interstellar clouds reproduce the C and
N isotopic compositions of IAOM in chondrites, IDPs, and Ryugu
samples, with the isotopic anomalies produced in specific molecules
(17, 48–50). While the abundances of N-bearing molecules do not
vary with gas density, the abundances of the C-bearing molecules
are generally greater at lower densities and when C/O > 1 (49).
The IAOM in clasts 1 and 2 likely formed where the physical and
chemical conditions were favorable for C isotopic fractionation, and
the resulting anomalies escaped equilibration with isotopically
normal CO. The paucity of C-anomalous IAOM in chondritic me-
teorites and IDPs suggests that the chemical reactions that fraction-
ate N were more efficient or widespread than those that fractionate
C (49), the molecules in which C fractionates were depleted in the
environment where most IAOM formed, the conditions were not
conducive to C isotopic fractionation (50), and/or equilibration
was prevalent.
Our studies of grain A0040 collected during the first touchdown
of the Hayabusa2 spacecraft and grain C0002 collected during the
Fig. 5. Abundances of presolar grains in Ryugu, carbonaceous chondrites, and an AMM. Abundances of presolar silicates and oxides (O-rich), SiC, and graphite in
clasts 1 and 2 and Ryugu matrix compared to abundances in chondrites of various classes [(9) and references therein (10, 18, 19, 22, 33, 36, 37, 51)] and an AMM (31). The
abundances in Ryugu are consistent with CI chondrites except for clasts 1 and 2, which have remarkably high abundances of presolar SiC grains. The presolar silicate
abundance in clast 1 is similar to primitive chondrites and not altered CI. Presolar O-rich grain abundances for A0040 clast 2, total Ryugu without clasts, and Ivuna (22) are
upper limits. Errors are 1σ. wo, without. Not plotted are presolar grain abundances in comet Wild 2 and IDPs. The abundance of O-rich presolar grains in comet Wild 2
samples is 600 to 830 ppm, and the abundance of presolar SiC is 45 ppm (26). Anhydrous IDPs display a wide range of presolar abundances for O-rich grains (20 to 23,080
ppm including 1σ errors) and SiC grains (10 to 630 ppm including 1σ errors) (21, 27, 34, 35).
Fig. 4. Isotopic compositions and abundances of IAOM in the Ryugu matrix and primitive clasts 1 and 2. The IAOM in the different lithologies has similar C and N
isotopic distributions (A). However, the clasts have much higher abundances of IAOM [%; (B)] than the Ryugu matrix. Isotopically normal organic matter is not plotted.
Errors in (A) are 1σ.
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7. second touchdown revealed a difference in the organic matter. Al-
though the abundance of IAOM with C isotopic anomalies were the
same in the hydrated matrices of C0002 and A0040, the abundance
of N anomalous IAOM was greater in the A0040 matrix. The
average 12
C14
N/12
C ratios of both the isotopically normal organic
matter and IAOM in A0040 are two times the ratios in C0002.
This indicates that the organic matter in the matrix of A0040 was
more N-rich than the matrix of C0002, though not as N-rich as
the primitive clasts. These differences likely reflect inherent hetero-
geneity of organic matter in Ryugu rather than alteration during po-
tential exposure of A0040 on the surface of Ryugu. Processes that
fractionate N would also be expected to fractionate C and the ma-
trices of A0040 and C0002 had the same abundance of C anoma-
lous IAOM.
Origin of clasts in Ryugu samples
The uniquely primitive characteristics of clasts 1 and 2 set them
apart from the bulk of the Ryugu matrix and any other known ex-
traterrestrial materials. These clasts have (i) moderate abundance of
preserved presolar silicate grains, (ii) primitive mineralogy, (iii)
abundances of presolar SiC exceeding any other sample, (iv) high
abundances of organic matter with N isotopic anomalies, (v) abun-
dances of organic matter with C isotopic anomalies exceeding any
other sample, and (vi) very high abundances of N-rich organic
matter. While some CR chondrites and chondritic IDPs have pre-
solar SiC or IAOM abundances approaching those in these clasts, no
sample has similarly high abundances of both constituents. More-
over, the abundance of C-anomalous IAOM in clasts 1 and 2 is
unparalleled.
The abundance of presolar silicates and the mineralogy of clast 1
indicate that it experienced limited aqueous alteration, unlike bulk
Ryugu. However, the other characteristics of clasts 1 and 2 cannot be
explained by more limited aqueous alteration relative to the host
Ryugu matrix. Presolar SiC is not altered or destroyed by aqueous
alteration. This is exemplified by the similar abundances of these
grains in hydrated and less altered chondrites (10), AMMs (31),
an anhydrous IDP (35), and comet Wild 2 (26). The abundance
of presolar SiC in the Ryugu matrix is comparable to these
samples. Therefore, parent body aqueous alteration cannot
explain the lower abundance of presolar SiC in the Ryugu matrix
compared to the clasts. The similar C and N isotopic distributions
of organic matter in the clasts and Ryugu matrix indicate that the
molecular carriers of these anomalies are not destroyed and the iso-
topic anomalies are not diluted by aqueous alteration. Previous
studies of chondrites have also shown that aqueously altered
samples have similar N isotopic anomalies and abundances of
IAOM as less altered samples, including primitive anhydrous
IDPs and comet Wild 2 (see discussion above). Thus, the lower
abundance of IAOM in the Ryugu matrix is not attributable to
aqueous alteration. The lower abundance of organic matter in the
Ryugu matrix relative to the clasts also cannot be explained by
aqueous alteration. Altered CI chondrites have greater abundances
of C associated with organic matter than more primitive chondrites
[e.g., (47)].
Clasts 1 and 2 may therefore represent a previously unsampled
type of primitive chondritic material that accreted in a cold region
of the protoplanetary disk enriched in presolar grains and primor-
dial organics. We propose that these unique clasts are exogenous
and originated from an asteroid or comet in the outer solar
system. The bulk δD and δ15
N compositions (4), observation of
CO2-bearing water inclusions within pyrrhotite (3), and N/C
ratios of Ryugu samples (3) indicate that Ryugu also likely formed
in the outer solar system, similar to CI chondrites. Probable come-
tary samples have higher C abundances than CI chondrites and N-
rich organic matter. The significantly greater abundance of organic
matter in the clasts and its N-rich nature compared to bulk CI-like
Ryugu support a cometary origin. In addition, the presolar silicate
abundance in clast 1 is consistent with some anhydrous IDPs and
AMMs. The clasts have clearly escaped the extensive hydration ex-
perienced by the Ryugu matrix and have distinct boundaries with
the Ryugu matrix. It is therefore less likely that they were incorpo-
rated during accretion of the matrix material of Ryugu’s parent as-
teroid. Instead, the clasts most likely accreted onto Ryugu >5 million
years after solar system formation, when aqueous alteration ceased
on Ryugu’s progenitor body (1) and after the parent body was dis-
rupted to form Ryugu as a rubble pile at large radial distance (2).
While the other clasts studied here are chemically similar to
clasts 1 and 2, they differ substantially in their inventory of presolar
grains and IAOM and are indistinguishable from bulk Ryugu in that
regard. These clasts likely have a different origin from clasts 1 and 2.
Whereas clasts 1 and 2 have well-defined boundaries with the
Ryugu matrix, the diffuse nature of clasts 4 and 5 suggests that
they were part of the progenitor Ryugu planetesimal. Their chemi-
cal resemblance to primitive clasts 1 and 2 indicates that they were
not as extensively altered as the surrounding Ryugu matrix. These
nanometer-scale coordinated analyses of Ryugu returned samples
have provided incredibly detailed insights into the macroscale ac-
cretion and alteration processes that occurred on the Ryugu asteroid
and parent body, and the distribution of presolar grains and IAOM
in the protoplanetary disk. The preservation of abundant primitive
materials within a highly altered body cannot be observed remotely
and emphasizes the importance of laboratory analyses of re-
turned samples.
MATERIALS AND METHODS
Experimental design
The objective of the study was to characterize the presolar grains
and IAOM within various lithologies present in Ryugu samples.
This was done by conducting coordinated nanoscale isotopic,
chemical, and mineralogical analyses of isotopically anomalous
components and their host matrix. Samples were examined by
FE-SEM-EDX, NanoSIMS, and TEM assisted by focused ion
beam (FIB) sample preparation techniques.
Samples and preparation
Broken fragments from Ryugu grains from the first touchdown site
(A0040 from chamber A) and second touchdown site (C0002 from
chamber C) were examined in this study. The fragments were sub-
millimeter sized. The fragments were handpicked and pressed into
pure indium in two separate sample mounts. The samples were not
polished because of their highly friable nature and also to avoid con-
tamination and/or removal of soluble organic compounds by expo-
sure to solvents. Polished grains of San Carlos olivine and
Madagascar hibonite were also pressed into each mount and
served as reference materials. Additional isotopic carbonate and
amphibole standards were included in the mounts but not used
in this study. One fragment from C0002 and three fragments
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8. from A0040 were studied. The samples were coated with ~5 nm of
Pt using a Cressington 108 auto sputter coater for SEM and Nano-
SIMS analyses.
FE-SEM-EDX chemical analysis
Fragments of Ryugu grains C0002 and A0040 were first imaged and
characterized for their elemental compositions by FE-SEM-EDX.
The JEOL 7600F at NASA Johnson Space Center (JSC) was used
to capture ultrahigh spatial resolution (2 to 3 nm) secondary elec-
tron images (SEIs), and backscattered electron images (BEIs) of the
samples. The SEIs were used to identify flat regions of the sample
that would be appropriate for NanoSIMS isotopic analysis. Detailed
images of these regions were acquired along with elemental x-ray
maps of Ti, Si, S, P, O, Ni, Na, Mg, K, In, Fe, Cr, Cl, Ca, C, and
Al. The JEOL 7600F is equipped with a silicon drift detector
(SDD)–type x-ray detector system, which can acquire and process
>100,000 x-ray counts per second.
Among a phyllosilicate-dominated groundmass were magnetite
framboids, plaquettes and spherules, carbonates, sulfides, Al-rich
and Fe-rich oxides, chromite, Mg-rich silicates, and carbonaceous
veins, nodules, and globules. The BEI and elemental maps allowed
for detection of clasts, which appeared lighter in the BEI and chem-
ically distinct from surrounding matrix. These clasts were irregular-
ly shaped and existed as discrete regions <100 μm in size and as
more diffuse regions. They were relatively Fe- and S-rich and Mg-
and Si-poor compared to the surrounding Ryugu matrix. Clast 1
was also Ni-rich and Na-poor and contained <~2-μm–sized Mg-
rich silicates, likely olivine.
NanoSIMS isotopic analysis
Isotopic analysis of the Ryugu samples was conducted using the
CAMECA NanoSIMS 50L at NASA JSC. We followed analytical
protocols that are well established in our laboratory [e.g., (27)].
Matrix regions in C0002 and A0040, one clast in C0002, and four
clasts in A0040 were analyzed. The isotopic compositions of the
samples were acquired by raster ion imaging using a 16-keV Cs+
primary ion beam of ~0.9 pA and ~100 nm diameter. Before
image acquisition, each analysis region was presputtered using a
high beam current to remove the Pt coating, clean the sample
surface, and ensure that secondary ion count rates reached a
steady state. Negative secondary ions of the C and O isotopes,
28
Si, and either 24
Mg16
O or 27
Al16
O were collected simultaneously
in electron multipliers. A mass resolving power of ~10,000
(CAMECA NanoSIMS definition) was achieved, and isobaric inter-
ferences were resolved. In particular, the 16
OH interference on 17
O
was <1‰. A nuclear magnetic resonance probe was used to main-
tain the magnetic field stability to <10 ppm/10 hours; 20-μm fields
of view were measured at an image size of 256 × 256 pixels. The
dwell time was 3200 μs per pixel, and 60 image layers were acquired
for each sample region. Automatic peak centering was conducted
on 12
C and 16
O every 10 frames during the analyses to correct for
any drift in the mass peaks. The other mass peaks were shifted ac-
cordingly. An electron flood gun was used to mitigate sample charg-
ing. To correct for instrumental mass fractionation, we measured
San Carlos olivine to correct for O isotopes and USGS24 graphite
for C isotopes. The graphite standard was on a separate mount and
consisted of grains pressed into clean Au foil.
The interactive data language (IDL)–based L’image software, de-
veloped by L. Nittler, was used for data processing, and the
following corrections were applied for each image pixel: deadtime
correction of 44 ns, quasi-simultaneous arrival correction, and cor-
rection for shifts between image layers. Image layers are summed,
and isotope ratio images are produced. Regions of interest are man-
ually defined, and a grain was considered presolar if its isotopic
composition differed from the surrounding material by >4σ.
Likely phase identifications were based on the 28
Si/12
C, 28
Si/16
O,
and 24
Mg16
O/16
O ratios; however, phases for representative grains
were confirmed by TEM (see section below). Isotope ratio errors are
based on counting statistical uncertainties and external reproduc-
ibility of standards. Ratios are reported as delta (δ) values, or per
mil deviations (‰) from the reference value, and are calculated
as δR (‰) = [Rsample/Rstandard − 1] × 1000, where R is the isotopic
ratio of the sample and standard (table S1).
The area analyzed in each region for C and O isotopes was as-
sessed on the basis of the NanoSIMS 16
O ion image with a 10%
threshold applied. In other words, regions with counts below 10%
of the maximum 16
O counts were excluded. Total analyzed areas for
different samples and lithologies are reported in table S2. Presolar
grain abundances were determined by dividing the total area
covered by the presolar grains by the total area measured and are
reported as ppm. Grain sizes are estimated from the NanoSIMS
images. Errors in reported presolar grain abundances are based
on the number of grains identified and use the confidence limits
tables in (52). For regions where no presolar O-rich grains were
identified, the 1σ upper limits on the abundances, given in table
S2, were determined by using the average presolar O-rich grain
size of 250 nm.
Some regions in clasts 1 and 2 and the matrix of C0002 and
A0040 that were analyzed for C and O isotopes were remeasured
for C, N, and Si isotopes to further characterize C-rich presolar
grains (fig. S3) and to identify IAOM (table S3). Some of the C-
rich presolar grains sputtered away during this subsequent analysis,
and N and Si isotopic compositions for these grains could not be
obtained. 12
C−
, 13
C−
, 12
C14
N−
, 12
C15
N−
, 28
Si−
, 29
Si−
, and 30
Si−
were measured simultaneously by ion imaging. Analytical protocols
were similar to the previous measurement setup. USGS24 graphite
was the reference material for the presolar grains for C isotopes. The
KG17 kerogen standard was the reference material for N isotopes,
and Si isotopic compositions were normalized to the average com-
position of the neighboring grains within the same imaged area. For
organic matter, KG17 kerogen was the reference material for C and
N isotopes. Organic matter was considered anomalous if its C and/
or N isotopic ratios differed by at least 3σ from the average compo-
sition of the analyzed regions.
The concentration of IAOM was determined by dividing the area
of anomalous organics by the total area analyzed. The area analyzed
in each region was assessed on the basis of the 28
Si ion image, with a
10% threshold applied to the 28
Si counts. The total areas analyzed
for C, N, and Si isotopes in clasts 1 and 2, the C0002 matrix, and the
A0040 matrix were 1906, 4616, 5705, and 3401 μm2
, respectively.
While grains with modest C anomalies (δ13
C ~ ±250‰) and low
28
Si/16
O ratios were identified during the C and O isotope
mapping and are likely organic, these grains are not reported here
because we do not have the corresponding N isotopic compositions
to constrain their nature further (i.e., organic or presolar graphite).
Only organic grains that were analyzed simultaneously for C and N
isotopes are reported and included in the abundance calculation.
This does not lead to an underestimate of the abundances of
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9. IAOM because the areas analyzed for C and O isotopes were not
included in the total area analyzed when calculating the
abundances.
Phase identifications of presolar silicates, presolar SiC, presolar
graphite, and organic matter were based on the 28
Si/12
C, 28
Si/16
O,
and 24
Mg16
O/16
O ratios from NanoSIMS analysis. The relevant
ratios for each grain are provided in tables S1 and S3. The TEM anal-
ysis of the presolar silicate and presolar SiC grains also assisted with
phase identifications. A presolar grain was considered to be a silicate
if its 28
Si/16
O and 24
Mg16
O/16
O ratios were equal to or greater than
the average for the surrounding material, which is mainly composed
of silicate grains. A grain was considered to be a SiC if a distinct 28
Si
signal was observed to correlate with the isotopic anomaly or its
28
Si/12
C ratio was greater than 0.3. The relatively low 28
Si/12
C
ratios of some grains that clearly showed 28
Si in the ion image,
and thus were SiC, were due to contaminating signal from sur-
rounding carbonaceous organic matter. Grains having 28
Si/12
C
ratios lower than 0.3 were assigned as presolar graphite. Anomalous
organic grains had a similar range of 28
Si/12
C ratios as presolar
graphite, but their C and N isotopic signatures were distinct and
aided in phase assignment. O, C, N, and Si isotopic ratios are report-
ed relative to standard mean ocean water, Pee Dee Belemnite, air,
and the Ryugu matrix, respectively.
FIB sample preparation
O- and C-rich presolar grains and an organic grain having N and C
isotopic anomalies were extracted from the bulk sample and pre-
pared for TEM analysis using FIB lift-out techniques. The FEI
Quanta 3D-FEG 600 dual-beam FIB instrument at NASA JSC was
used to produce thin (~100 nm) electron transparent cross sections
of the grains and surrounding matrix. These sections were welded
onto Cu grids for TEM analysis. Further description of the FIB
sample preparation procedure can be found in (11).
TEM mineralogical and chemical analysis
The FIB sections were analyzed using a JEOL 2500SE 200 kV FE-
STEM equipped with a JEOL 70 mm2
SDD for EDX analyses. STEM
images were collected in brightfield and darkfield modes. High-res-
olution (lattice fringe) images and selected-area electron diffraction
(SAED) patterns were collected using a Gatan OneView camera.
The compositional maps were acquired by rastering a 2-nm-diam-
eter incident probe with a dwell time of 50 ms per pixel over a frame
size of 200 × 256 pixels per frame. Multiple frames (200 to 500) were
summed so that each pixel contains high-count EDX spectrum suf-
ficient to provide better than 1% counting statistics to determine
major elemental abundances (multiple pixels are summed to
define a region of interest) and their spatial distributions. Quantita-
tive analyses were obtained using the Cliff-Lorimer thin-film proce-
dure, with experimental k-factors determined using well-
characterized standards.
Supplementary Materials
This PDF file includes:
Figs. S1 to S10
Legends for tables S1 and S3
Table S2
References
Other Supplementary Material for this
manuscript includes the following:
Tables S1 and S3
REFERENCES AND NOTES
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N. Dauphas, A. M. Davis, T. Di Rocco, W. Fujiya, R. Fukai, I. Gautam, M. K. Haba, Y. Hibiya, H.
Hidaka, H. Homma, P. Hoppe, G. R. Huss, K. Ichida, T. Iizuka, T. R. Ireland, A. Ishikawa, M. Ito, S.
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Acknowledgments: We thank K. Thomas-Keprta and L. Le for their assistance with the FE-SEM
and Z. Rahman for production of FIB cross sections. Hayabusa2 was developed and built under
the leadership of Japan Aerospace Exploration Agency (JAXA), with contributions from the
German Aerospace Center (DLR) and the Centre National d’Études Spatiales (CNES), and in
collaboration with NASA, and other universities, institutes, and companies in Japan. The
curation system was developed by JAXA in collaboration with companies in Japan. Funding:
This work was supported by grant NNH15ZDA001N from the NASA Hayabusa2 Participating
Scientist Program to A.N.N. L.P. was supported by the Centre national d’études spatiales (CNES)
for the sample preparation. Author contributions: A.N.N. conceptualized and supervised the
research project, conducted NanoSIMS isotopic analyses, assisted with FIB sample production,
and wrote the manuscript with contributions from P.M., L.P.K., and L.P. L.P. prepared the bulk
Hayabusa2 samples and some standards. P.M. conducted FE-SEM-EDX analyses. L.P.K.
conducted TEM analyses. All authors contributed to the review of the manuscript. Competing
interests: The authors declare that they have no competing interests. Data and materials
availability: All data needed to evaluate the conclusions in the paper are present in the paper
and/or the Supplementary Materials. Data of Hayabusa2 sample and other data from the
mission are available at the JAXA Data Archives and Transmission System (DARTS) archive at
https://darts.isas.jaxa.jp/curation/hayabusa2 and https://darts.isas.jaxa.jp/planet/project/
hayabusa2/.
Submitted 9 February 2023
Accepted 9 June 2023
Published 14 July 2023
10.1126/sciadv.adh1003
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