Ferric iron as well as magnetite are rarely found in lunar samples, and their
distribution and formation mechanisms on the Moon have not been well
studied. Here, we discover sub-microscopic magnetite particles in Chang’E-5
lunar soil. Magnetite and puremetallic iron particles are embedded in oxygendissolved
iron-sulfide grains from the Chang’E-5 samples. This mineral
assemblage indicates a FeO eutectoid reaction (4FeO = Fe3O4+Fe) for formation
of magnetite. The iron-sulfide grains’ morphology features and the
oxygen’s distribution suggest that a gas–melt phase reaction occurred during
large-impact events. This could provide an effective method to form ubiquitous
sub-microscopic magnetite in fine lunar soils and be a contributor to the
presentation of ferric iron on the surface of the Moon. Additionally, the formation
of sub-microscopic magnetite and metallic iron by eutectoid reaction
may provide an alternative way for the formation of magnetic anomalies
observed on the Moon.
A detailed geological history of quartz and industrial minerals present in different localities of
Eritrea is given. Well-grown transparent quartz crystals reflecting the hexagonal crystallographic features and
isolated, irregular shaped small milky quartz stones are found in western suburb of Asmara and the area
between Molebso and Zara in central northern Eritrea. Mechanism of formation of growth features observed on
the habit faces of transparent quartz crystals is briefly explained. Micro-topographical studies carried out on
these crystals indicate that to begin with, they grow and develop under high supersaturating conditions.
Most of the milky quartz stones are observed to be generally randomly scattered and devoid of gold. However,
few such specimens having yellow colored dots on their surfaces contain gold particles. Energy dispersion of Xray
analysis (EDAX) indicates high content of gold to the tune of 48% present in such samples. Commercial
implications related to quartz bearing gold are discussed. It is proposed that gold exists in large quantity in
quartz veins deep beneath the surface of earth in this region.
Age of Jupiter inferred from the distinct genetics and formation times of met...Sérgio Sacani
The age of Jupiter, the largest planet in our Solar System, is still
unknown. Gas-giant planet formation likely involved the growth
of large solid cores, followed by the accumulation of gas onto
these cores. Thus, the gas-giant cores must have formed before
dissipation of the solar nebula, which likely occurred within less
than 10 My after Solar System formation. Although such rapid
accretion of the gas-giant cores has successfully been modeled,
until now it has not been possible to date their formation. Here,
using molybdenum and tungsten isotope measurements on iron
meteorites, we demonstrate that meteorites derive from two
genetically distinct nebular reservoirs that coexisted and remained
spatially separated between ∼1My and ∼3–4My after Solar System
formation. The most plausible mechanism for this efficient separation
is the formation of Jupiter, opening a gap in the disk and
preventing the exchange of material between the two reservoirs.
As such, our results indicate that Jupiter’s core grew to ∼20 Earth
masses within <1 My, followed by amore protracted growth to ∼50
Earth masses until at least ∼3–4 My after Solar System formation.
Thus, Jupiter is the oldest planet of the Solar System, and its solid
core formed well before the solar nebula gas dissipated, consistent
with the core accretion model for giant planet formation.
Characterising the true descendants of the first starsSérgio Sacani
The metal-poor stars in the Galactic halo are thought to showthe imprints of the first (Pop III) stars, and thus provide a glance at the
first episodes of star formation. In this work, we aim at understanding whether all very metal-poor stars formed in environments
polluted by Pop III supernovae (SNe) and at what level. With a general parametric model for early metal enrichment, we
study the chemical abundances (from C to Zn) of an environment imprinted by a single Pop III SN. We investigate how these
abundances depend on the initial mass and internal mixing of Pop III stars, as well as on their SN explosion energy. We then
study how subsequent generations of normal (Pop II) SNe affect the Pop III chemical signatures. By comparing the observed
chemical abundances with our model predictions, we show that stars with [C/Fe] > +2.5 form in environments polluted purely
by low-energy Pop III SNe (𝐸SN < 2×1051 erg). At lower [C/Fe], stars can be imprinted either by Pop III only, or also by normal
Pop II SNe. The probability of being enriched by Pop II SNe increases as [C/Fe] decreases. When Pop II stars contribute more
to the pollution, they wash out the diverse chemical peculiarities left by the different Pop III SNe, and the chemical dispersion
between their descendants decreases.We conclude that C-normal stars ([C/Fe] ≤ +0.7) have likely been enriched by Pop II SNe
at a ≥ 50% level and we identify in the abundance scatter a key diagnostic to pinpoint the signature of Pop III SNe.
Geochemistry and Genesis of Kammatturu Iron Ores of Devagiri Formation, Sandu...IJMER
The Greenstone belts of Karnataka are enriched in BIFs in Dharwar craton, where Iron
formations are confined to the basin shelf, clearly separated from the deeper-water iron formation that
accumulated at the basin margin and flanking the marine basin. Geochemical data procured in terms of
major, trace and REE are plotted in various diagrams to interpret the genesis of BIFs. Al2O3, Fe2O3 (T),
TiO2, CaO, and SiO2 abundances and ratios show a wide variation. Ni, Co, Zr, Sc, V, Rb, Sr, U, Th,
ΣREE, La, Ce and Eu anomalies and their binary relationships indicate that wherever the terrigenous
component has increased, the concentration of elements of felsic such as Zr and Hf has gone up. Elevated
concentrations of Ni, Co and Sc are contributed by chlorite and other components characteristic of basic
volcanic debris. The data suggest that these formations were generated by chemical and clastic
sedimentary processes on a shallow shelf. During transgression, chemical precipitation took place at the
sediment-water interface, whereas at the time of regression. Iron ore formed with sedimentary structures
and textures in Kammatturu area, in a setting where the water column was oxygenated.
Iron isotopes trace primordial magma ocean cumulates melting in Earth’s upper...Sérgio Sacani
The differentiation of Earth ~4.5 billion years (Ga) ago is believed to have culminated in magma ocean crystallization, crystal-liquid separation, and the formation of mineralogically distinct mantle reservoirs. However, the magma ocean model remains difficult to validate because of the scarcity of geochemical tracers of lower mantle mineralogy. The Fe isotope compositions (57Fe) of ancient mafic rocks can be used to reconstruct the mineralogy of their mantle source regions. We present Fe isotope data for 3.7-Ga metabasalts from the Isua Supracrustal Belt (Greenland). The 57Fe signatures of these samples extend to values elevated relative to modern equivalents and define strong correlations with fluid-immobile trace elements and tungsten isotope anomalies (182W). Phase equilibria models demonstrate that these features can be explained by melting of a magma ocean cumulate component in the up-per mantle. Similar processes may operate today, as evidenced by the 57Fe and 182W heterogeneity of modern oceanic basalts
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
International Refereed Journal of Engineering and Science (IRJES) is a peer reviewed online journal for professionals and researchers in the field of computer science. The main aim is to resolve emerging and outstanding problems revealed by recent social and technological change. IJRES provides the platform for the researchers to present and evaluate their work from both theoretical and technical aspects and to share their views.
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.
We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part
of the Survey of H I in Extremely Low-Mass Dwarfs (SHIELD) project, which is a multi-wavelength
study of galaxies with H I masses in the range of 106-107:2 M discovered by the ALFALFA survey.
We have obtained spectra of the lone H II region in AGC 198691 with the new high-throughput
KPNO Ohio State Multi-Object Spectrograph (KOSMOS) on the Mayall 4-m as well as with the Blue
Channel spectrograph on the MMT 6.5-m telescope. These observations enable the measurement of the
temperature-sensitive [O III]4363 line and hence the determination of a \direct" oxygen abundance
for AGC 198691. We nd this system to be an extremely metal-decient (XMD) system with an
oxygen abundance of 12+log(O/H) = 7.02 0.03, making AGC 198691 the lowest-abundance starforming
galaxy known in the local universe. Two of the ve lowest-abundance galaxies known have
been discovered by the ALFALFA blind H I survey; this high yield of XMD galaxies represents a
paradigm shift in the search for extremely metal-poor galaxies.
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.
More Related Content
Similar to Sub-microscopicmagnetite andmetallic iron particles formed by eutectic reaction in Chang’E-5 lunar soil
A detailed geological history of quartz and industrial minerals present in different localities of
Eritrea is given. Well-grown transparent quartz crystals reflecting the hexagonal crystallographic features and
isolated, irregular shaped small milky quartz stones are found in western suburb of Asmara and the area
between Molebso and Zara in central northern Eritrea. Mechanism of formation of growth features observed on
the habit faces of transparent quartz crystals is briefly explained. Micro-topographical studies carried out on
these crystals indicate that to begin with, they grow and develop under high supersaturating conditions.
Most of the milky quartz stones are observed to be generally randomly scattered and devoid of gold. However,
few such specimens having yellow colored dots on their surfaces contain gold particles. Energy dispersion of Xray
analysis (EDAX) indicates high content of gold to the tune of 48% present in such samples. Commercial
implications related to quartz bearing gold are discussed. It is proposed that gold exists in large quantity in
quartz veins deep beneath the surface of earth in this region.
Age of Jupiter inferred from the distinct genetics and formation times of met...Sérgio Sacani
The age of Jupiter, the largest planet in our Solar System, is still
unknown. Gas-giant planet formation likely involved the growth
of large solid cores, followed by the accumulation of gas onto
these cores. Thus, the gas-giant cores must have formed before
dissipation of the solar nebula, which likely occurred within less
than 10 My after Solar System formation. Although such rapid
accretion of the gas-giant cores has successfully been modeled,
until now it has not been possible to date their formation. Here,
using molybdenum and tungsten isotope measurements on iron
meteorites, we demonstrate that meteorites derive from two
genetically distinct nebular reservoirs that coexisted and remained
spatially separated between ∼1My and ∼3–4My after Solar System
formation. The most plausible mechanism for this efficient separation
is the formation of Jupiter, opening a gap in the disk and
preventing the exchange of material between the two reservoirs.
As such, our results indicate that Jupiter’s core grew to ∼20 Earth
masses within <1 My, followed by amore protracted growth to ∼50
Earth masses until at least ∼3–4 My after Solar System formation.
Thus, Jupiter is the oldest planet of the Solar System, and its solid
core formed well before the solar nebula gas dissipated, consistent
with the core accretion model for giant planet formation.
Characterising the true descendants of the first starsSérgio Sacani
The metal-poor stars in the Galactic halo are thought to showthe imprints of the first (Pop III) stars, and thus provide a glance at the
first episodes of star formation. In this work, we aim at understanding whether all very metal-poor stars formed in environments
polluted by Pop III supernovae (SNe) and at what level. With a general parametric model for early metal enrichment, we
study the chemical abundances (from C to Zn) of an environment imprinted by a single Pop III SN. We investigate how these
abundances depend on the initial mass and internal mixing of Pop III stars, as well as on their SN explosion energy. We then
study how subsequent generations of normal (Pop II) SNe affect the Pop III chemical signatures. By comparing the observed
chemical abundances with our model predictions, we show that stars with [C/Fe] > +2.5 form in environments polluted purely
by low-energy Pop III SNe (𝐸SN < 2×1051 erg). At lower [C/Fe], stars can be imprinted either by Pop III only, or also by normal
Pop II SNe. The probability of being enriched by Pop II SNe increases as [C/Fe] decreases. When Pop II stars contribute more
to the pollution, they wash out the diverse chemical peculiarities left by the different Pop III SNe, and the chemical dispersion
between their descendants decreases.We conclude that C-normal stars ([C/Fe] ≤ +0.7) have likely been enriched by Pop II SNe
at a ≥ 50% level and we identify in the abundance scatter a key diagnostic to pinpoint the signature of Pop III SNe.
Geochemistry and Genesis of Kammatturu Iron Ores of Devagiri Formation, Sandu...IJMER
The Greenstone belts of Karnataka are enriched in BIFs in Dharwar craton, where Iron
formations are confined to the basin shelf, clearly separated from the deeper-water iron formation that
accumulated at the basin margin and flanking the marine basin. Geochemical data procured in terms of
major, trace and REE are plotted in various diagrams to interpret the genesis of BIFs. Al2O3, Fe2O3 (T),
TiO2, CaO, and SiO2 abundances and ratios show a wide variation. Ni, Co, Zr, Sc, V, Rb, Sr, U, Th,
ΣREE, La, Ce and Eu anomalies and their binary relationships indicate that wherever the terrigenous
component has increased, the concentration of elements of felsic such as Zr and Hf has gone up. Elevated
concentrations of Ni, Co and Sc are contributed by chlorite and other components characteristic of basic
volcanic debris. The data suggest that these formations were generated by chemical and clastic
sedimentary processes on a shallow shelf. During transgression, chemical precipitation took place at the
sediment-water interface, whereas at the time of regression. Iron ore formed with sedimentary structures
and textures in Kammatturu area, in a setting where the water column was oxygenated.
Iron isotopes trace primordial magma ocean cumulates melting in Earth’s upper...Sérgio Sacani
The differentiation of Earth ~4.5 billion years (Ga) ago is believed to have culminated in magma ocean crystallization, crystal-liquid separation, and the formation of mineralogically distinct mantle reservoirs. However, the magma ocean model remains difficult to validate because of the scarcity of geochemical tracers of lower mantle mineralogy. The Fe isotope compositions (57Fe) of ancient mafic rocks can be used to reconstruct the mineralogy of their mantle source regions. We present Fe isotope data for 3.7-Ga metabasalts from the Isua Supracrustal Belt (Greenland). The 57Fe signatures of these samples extend to values elevated relative to modern equivalents and define strong correlations with fluid-immobile trace elements and tungsten isotope anomalies (182W). Phase equilibria models demonstrate that these features can be explained by melting of a magma ocean cumulate component in the up-per mantle. Similar processes may operate today, as evidenced by the 57Fe and 182W heterogeneity of modern oceanic basalts
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
International Refereed Journal of Engineering and Science (IRJES) is a peer reviewed online journal for professionals and researchers in the field of computer science. The main aim is to resolve emerging and outstanding problems revealed by recent social and technological change. IJRES provides the platform for the researchers to present and evaluate their work from both theoretical and technical aspects and to share their views.
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.
We present spectroscopic observations of the nearby dwarf galaxy AGC 198691. This object is part
of the Survey of H I in Extremely Low-Mass Dwarfs (SHIELD) project, which is a multi-wavelength
study of galaxies with H I masses in the range of 106-107:2 M discovered by the ALFALFA survey.
We have obtained spectra of the lone H II region in AGC 198691 with the new high-throughput
KPNO Ohio State Multi-Object Spectrograph (KOSMOS) on the Mayall 4-m as well as with the Blue
Channel spectrograph on the MMT 6.5-m telescope. These observations enable the measurement of the
temperature-sensitive [O III]4363 line and hence the determination of a \direct" oxygen abundance
for AGC 198691. We nd this system to be an extremely metal-decient (XMD) system with an
oxygen abundance of 12+log(O/H) = 7.02 0.03, making AGC 198691 the lowest-abundance starforming
galaxy known in the local universe. Two of the ve lowest-abundance galaxies known have
been discovered by the ALFALFA blind H I survey; this high yield of XMD galaxies represents a
paradigm shift in the search for extremely metal-poor galaxies.
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.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
DERIVATION OF MODIFIED BERNOULLI EQUATION WITH VISCOUS EFFECTS AND TERMINAL V...Wasswaderrick3
In this book, we use conservation of energy techniques on a fluid element to derive the Modified Bernoulli equation of flow with viscous or friction effects. We derive the general equation of flow/ velocity and then from this we derive the Pouiselle flow equation, the transition flow equation and the turbulent flow equation. In the situations where there are no viscous effects , the equation reduces to the Bernoulli equation. From experimental results, we are able to include other terms in the Bernoulli equation. We also look at cases where pressure gradients exist. We use the Modified Bernoulli equation to derive equations of flow rate for pipes of different cross sectional areas connected together. We also extend our techniques of energy conservation to a sphere falling in a viscous medium under the effect of gravity. We demonstrate Stokes equation of terminal velocity and turbulent flow equation. We look at a way of calculating the time taken for a body to fall in a viscous medium. We also look at the general equation of terminal velocity.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
Nucleophilic Addition of carbonyl compounds.pptxSSR02
Nucleophilic addition is the most important reaction of carbonyls. Not just aldehydes and ketones, but also carboxylic acid derivatives in general.
Carbonyls undergo addition reactions with a large range of nucleophiles.
Comparing the relative basicity of the nucleophile and the product is extremely helpful in determining how reversible the addition reaction is. Reactions with Grignards and hydrides are irreversible. Reactions with weak bases like halides and carboxylates generally don’t happen.
Electronic effects (inductive effects, electron donation) have a large impact on reactivity.
Large groups adjacent to the carbonyl will slow the rate of reaction.
Neutral nucleophiles can also add to carbonyls, although their additions are generally slower and more reversible. Acid catalysis is sometimes employed to increase the rate of addition.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
ANAMOLOUS SECONDARY GROWTH IN DICOT ROOTS.pptxRASHMI M G
Abnormal or anomalous secondary growth in plants. It defines secondary growth as an increase in plant girth due to vascular cambium or cork cambium. Anomalous secondary growth does not follow the normal pattern of a single vascular cambium producing xylem internally and phloem externally.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...
Sub-microscopicmagnetite andmetallic iron particles formed by eutectic reaction in Chang’E-5 lunar soil
1. Article https://doi.org/10.1038/s41467-022-35009-7
Sub-microscopic magnetite and metallic iron
particles formed by eutectic reaction in
Chang’E-5 lunar soil
Zhuang Guo1,2,3
, Chen Li1,4
, Yang Li 1,5
, Yuanyun Wen1
, Yanxue Wu6
,
Bojun Jia 2
, Kairui Tai1,7
, Xiaojia Zeng1
, Xiongyao Li 1,5
, Jianzhong Liu1,5
&
Ziyuan Ouyang1
Ferric iron as well as magnetite are rarely found in lunar samples, and their
distribution and formation mechanisms on the Moon have not been well
studied. Here, we discover sub-microscopic magnetite particles in Chang’E-5
lunar soil. Magnetite and pure metallic iron particles are embedded in oxygen-
dissolved iron-sulfide grains from the Chang’E-5 samples. This mineral
assemblage indicates a FeO eutectoid reaction (4FeO = Fe3O4 + Fe) for for-
mation of magnetite. The iron-sulfide grains’ morphology features and the
oxygen’s distribution suggest that a gas–melt phase reaction occurred during
large-impact events. This could provide an effective method to form ubiqui-
tous sub-microscopic magnetite in fine lunar soils and be a contributor to the
presentation of ferric iron on the surface of the Moon. Additionally, the for-
mation of sub-microscopic magnetite and metallic iron by eutectoid reaction
may provide an alternative way for the formation of magnetic anomalies
observed on the Moon.
Traditionally, the Moon is considered to be extremely reduced. Thus,
the oxidation state of the lunar surface points to formation of metallic
iron rather than iron oxides1
. Although recent remote sensing and
sample analysis data indicate the presence of Fe3+
on the lunar surface,
its distribution form and formation mechanism are unknown2–4
. Mag-
netite is an important host mineral of Fe3+
, and it is rarely present in
lunar samples. In the Apollo era, there are some studies that deduced
the presence of ubiquitous sub-microscopic magnetite-like phases in
Apollo soils based on electron spin resonance and Mössbauer spec-
troscopy, but there is no further in situ mineralogical evidence for the
presence of widespread magnetite crystals in lunar soils5–8
. Some
micron-sized magnetite grains have been identified in lunar samples,
and they are closely associated with exogenous carbonaceous chon-
drite impactors, but these are isolated cases and there is no evidence
for widespread distribution of magnetite grains in the finest lunar
soils2,9,10
. Therefore, the distribution forms of magnetite on the lunar
surface remains a mystery, and the native magnetite products on the
Moon are not known.
Lunar magnetic anomalies have been a mystery since the Apollo
era11–14
. Magnetite, an important ferromagnetic mineral, has not been
considered as a carrier of lunar magnetic anomalies owing to the
highly reducing conditions on the Moon15,16
. Therefore, an in-depth
understanding of the formation mechanism and distribution char-
acteristics of magnetite on the Moon could provide a new perspective
to explain the genesis of magnetic anomalies in the lunar crust.
China’s Chang’E-5 mission successfully returned 1.731 kg of new
lunar soils from the young lunar mare basalt unit Em4/P58 (~2.0 Ga).
Almost all of the Chang’E-5 regolith was local materials, with only a few
Received: 22 October 2022
Accepted: 14 November 2022
Check for updates
1
Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, 550081 Guiyang, China. 2
Institute of Remote Sensing and
Geographical Information System, School of Earth and Space Sciences, Peking University, 100871 Beijing, China. 3
College of Earth and Planetary Sciences,
University of Chinese Academy of Sciences, 100049 Beijing, China. 4
Faculty of Metallurgical and Energy Engineering, Kunming University of Science and
Technology, 650093 Kunming, China. 5
Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, 230026 Hefei, China. 6
Guangdong
University of Technology, 510006 Guangzhou, China. 7
State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University,
710069 Xi’an, China. e-mail: liyang@mail.gyig.ac.cn
Nature Communications| (2022)13:7177 1
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1234567890():,;
2. distant ejecta (<5%) from large-impact craters (Aristarchus, Sharp B,
Copernicus, and Harding)17,18
. Considering that the Chang’E-5 ejecta
formed at a young age and was subjected to very limited late mod-
ification processes, information about the initial response to large
impact processes on the lunar surface can be obtained19
. The discovery
of high-pressure minerals in Chang’E-5 soils demonstrates the con-
tribution of large-impact ejecta from the Chang’E-5 sampling region20
.
Here, we report high-quality mineralogical analyses of native
magnetite formed by eutectic reaction in Chang’E-5 samples. The
newly formed sub-microscopic magnetite and metallic iron under
large-impact conditions could greatly increase the magnetic suscept-
ibility of lunar surface materials, which is a potential agent for giant-
impact ejecta to exhibit significant magnetic anomalies.
Results
Overview of the iron-sulfide grains in Chang’E-5 lunar soil
X-ray diffraction and Raman spectroscopy results have shown that
iron-sulfide is a minor component of Chang’E-5 soil samples21–23
. Sev-
eralangular and spherical iron-sulfide grains were selected by scanning
electron microscopy (SEM) in our study (Supplementary Fig. 1).
Angular troilite always exhibits sporadic curved iron whiskers with
micro-scale length and a honeycomb-like mineral surface, as described
by Matsumoto et al. (Supplementary Fig. 1)24,25
. The angular troilite
indicates that the grains were relatively homogeneous internally and
did not exhibit complex mineral assemblages, suggesting that the
grains were directly broken off from the parent rock without
undergoing complex processes. In contrast, the spherical iron-sulfide
grains (<2 μm in diameter), resembling molten droplets, showed
unique morphological features in which the iron-rich components
uniformly protruded from the entire surface of the iron-sulfide grains,
showing a vermicular-like structure in the SEM images (Supplementary
Fig. 1). Cross sections of the spherical iron-sulfide grains showed
multiple mineral phases within the grains, which may provide addi-
tional evidence for the processes that occurred on the Moon (Fig. 1).
We mainly focused on the spherical iron-sulfide grains, and the
detailed information about the focused-ion-beam foils of these grains
is given below.
Transmission electron microscopy (TEM) observations showed
that the cross sections of the spherical iron-sulfide grains were ellip-
tical with long and short axes of 2.5 and 1.5 μm, respectively, which is
similar to the morphology of molten droplets (Fig. 1). Quantitative
TEM-energy dispersive X-ray (EDX) compositional maps indicated that
tentacles of pure iron (without Ni) protruded from the entire surface of
the spherical iron-sulfide grains at nearly equal intervals (Fig. 1, Sup-
plementary Fig. 2). In addition, the interiors of the grains contained
abundant minute inclusions of pure metallic iron (undetectable Ni)
and magnetite with sizes of ~100 nm, and the close spatial association
of these two embedded phases suggested a co-precipitation formation
(Figs. 1 and 2a). Based on selected-area electron diffraction (SAED)
patterns and high-resolution TEM images of the iron-sulfide grains, the
pure iron atthe peripheryof the particles and the interior iron particles
were identified to be α-iron (Fig. 1, Supplementary Fig. 3). The matrix
500nm
Pt
Ilm
0
Fe
Au
Iron sulfide
1
2
a
g
Tro+Po
Mag
0
Fe
b
500 nm
0
Fe
Iron sulfide
Pt
Ves
c
500 nm
0
Fe
Mag
d
a*Tro
c*Tro
[001] [110]
Tro Po
→
→
→
→
→
→
→
→
→
111*Po
002*Po
→
→
110*
α-Fe
→
200 nm
100 nm
pores
0
Fe
matrix
Ves
e
f
g
h
Fig. 1 | Overview of the studied spherical iron-sulfide grains. a–d Transmission
electron microscopy bright-field images of two spherical iron-sulfide grains and
their corresponding quantitative energy-dispersive element maps, showing a ring
of equally spaced pure-iron tentacles at the grain edges and a wide distribution of
iron-oxide (Mag) and pure-iron (Fe0
) inclusions within the troilite (Tro) and pyr-
rhotite (Po) matrix. e–f Selected-area electron diffraction patterns of the matrix
within an iron-sulfide grain and the iron tentacles around the grain edge, showing
intergrowth of troilite and pyrrhotite in the matrix and metallic iron (α-Fe) pro-
truding from the iron-sulfide grain. The diffraction area is indicated by the dashed
region in (a).g Morphological features at the edges of the studied iron-sulfide grain.
h Smaller vesicles (Ves) scattered within the grain.
Article https://doi.org/10.1038/s41467-022-35009-7
Nature Communications| (2022)13:7177 2
3. within the spherical iron-sulfide grains was identified to be intergrowth
of troilite and pyrrhotite, with pyrrhotite exhibiting weak reflections in
the SAED pattern. Troilite and pyrrhotite have a consistent topotaxial
relationship, showing a [001] zone-axis of troilite parallel to pyrrhotite
[1
10] (Fig. 1e). The electron energy-loss spectroscopy (EELS) spectra
and quantitative TEM-EDX results indicated that the iron-sulfide matrix
also contained a certain amount of oxygen (Supplementary Fig. 4,
Supplementary Table 1). TEM-EDX analysis gave an atomic Fe/S ratio of
about 1.25 for the bulk composition of the interiors of the spherical
iron-sulfide grains (including the magnetite, pure iron particles, and
troilite–pyrrhotite matrix), indicating that there should be at least
~20% of excess elemental Fe within the iron-sulfide grains (Fe1−XS,
X = 0–0.125) (Supplementary Table 1). Another feature of the spherical
iron-sulfide grains was that the pure-iron tentacles at the grain edges
c
100 nm
Line scan
Mag Mag
0
Fe
vesicles
a
matrix
Si
Fe
S
O
150 300 450
20
40
atom%
Mag
Tro+Po
Tro+Po Tro+Po
Mag
Distance/nm
(a)
(b)
(c)
Fe O
3 4
Fe O *
2 3
Fe SiO *
2 4
Energy loss (eV) Energy loss (eV)
Fe O *
2 3
Fe SiO *
2 4
L3
L2
Energy loss (eV)
Fe
O 2 nm
Mag [111]
20 nm 10 nm
Mag
0
Fe
Tro+Po
Mag
(022)*
(220)*
b
c d e
f g h
Fig. 2 | Identification of magnetite (Mag) in the iron-sulfide grains.
a Transmission electron microscopy (TEM) bright-field image of a region of
a spherical iron-sulfide grain focused-ion-beam section in which magnetite and
pure metallic iron particles have co-precipitated within the troilite–pyrrhotite
(Tro + Po) matrix with some scattered hexagonal vesicles. b Quantitative trans-
mission electron microscopy–energy-dispersive line-profile results obtained from
the position indicated by the arrow in (a). c, d O, K, and Fe L2,3 electron energy-loss
spectra of a magnetite particle (Fe3O4) embedded in the studied iron-sulfide grain.
The spectra of the prepared standards (Fe2O3 and Fe2SiO4) are marked by asterisks.
e Results of the best fit (coefficient of determination of 0.99) for the Fe-oxidation-
state ratio of the magnetite particle using the Fe L3 edge, showing an approximate
Fe3+
to Fe2+
ratio of 2:1 in the magnetite particle. f High-magnification high-angle
annular dark-field image of the magnetite particle, showing a close spatial rela-
tionship with metallic iron. g High-resolution TEM image of a magnetite particle.
The fast Fourier transform pattern of this grain is shown in the insert at the bottom
left of the figure. h Atomic-resolution annular dark-field scanning TEM image of a
magnetite particle. A magnetite structure model along the [
111] zone axis is
superimposed on the image.
Article https://doi.org/10.1038/s41467-022-35009-7
Nature Communications| (2022)13:7177 3
4. were intertwined with strands of S- and O-rich material and contained
numerous pores, with some areas containing Si and Ca (Supplemen-
tary Fig. 2). The pores at the edges of the grains were ~60 nm in dia-
meter, suggesting that a violent outgassing reaction occurred at the
edges of the grains (Fig. 1g). There were also some scattered smaller
vesicles (~20 nm) within the grains (Fig. 1h).
Identification of magnetite in the spherical iron-sulfide grains
The uniformly distributed iron-oxide particles with sizes of ~100 nm
embedded in the spherical iron-sulfide grains were discovered to be
magnetite by combined chemical and structural analyses. TEM-EDX
compositional maps and line profiles indicated that the iron-oxide
minerals within the spherical iron-sulfide grains were O- and Fe-rich
phases (Figs. 1 and 2b). The EELS oxygen K edge at ~530 eV and iron L2,3
edge at ~705 eV are the clearest diagnostic features for identifying
Fe3O4 in EELS spectra26
. The EELS spectrum of the iron-oxide particles
within the spherical iron-sulfide grains showed a pre-peak near 530 eV,
a weaker maximum at ~545–550 eV, and a dominant peak at 540 eV,
whose position and shape were between the standard O K edges of the
Fe2SiO4 and Fe2O3 spectra (Fig. 2c). These detailed EELS spectral
structures near 530 eV indicate the presence of Fe2O3 in the iron-oxide
particles, and they have similar characteristics to those of Fe3O4
26
. In
addition, the Fe L2,3 spectrum of the studied iron-oxide particles was
intermediate between the standard single-valence spectra, indicating
that both Fe2+
and Fe3+
were present in the iron-oxide particles within
the spherical iron-sulfide grains (Fig. 2d). The Fe3+
to Fe2+
ratio in the
iron-oxide particles was estimated to be ~2:1 by the EELS spectral peak
fitting method, which is consistent with the chemical composition of
magnetite (Fig. 2e). The structure of magnetite was further char-
acterized by aberration-corrected scanning TEM. Atomic-resolution
annular dark-field scanning TEM images reflecting the atomic mass
contrast of the materials were obtained, with O and Fe showing rela-
tively bright contrast in the images (Fig. 2h). High-resolution TEM
images of the iron-oxide particles along the [
111] zone axis indicated
(220) lattice fringes with a periodicity of 2.97 Å (Fig. 2g). The angle
between (220) and (0
22) in the fast Fourier transform pattern was
measured to be 120° (insert in Fig. 2g), which is consistent with the
crystal structure of magnetite. The iron-oxide particles embedded in
the spherical iron-sulfide grains were conclusively determined to be
magnetite crystals.
Discussion
The magnetite-bearing spherical iron-sulfide grains in the Chang’E-5
lunar fines were very small isolated grains (2 μm in diameter). The
spherical iron-sulfide grains were characterized by a ring of almost
equidistant pure-iron tentacles at the edges of the grains, and by the
ubiquitous sub-microscopic magnetite and metallic iron particles that
precipitated in the internal troilite–pyrrhotite matrix. These spherical
iron-sulfide grains with unique characteristics are an effective carrier
of very small magnetite particles in lunar soils and a form of Fe3+
dis-
tribution on the lunar surface, providing verification of previous
speculations about the ubiquity of very small magnetite particles in
lunar soils5–8,27
.
It is generally accepted that magnetite formation on the Moon is
most likely to be controlled by the C–O–H gas phase under the redu-
cing conditions of the lunar surface, and it is the most common
interpretation of lunar surface magnetite in previous studies2,10
. Joy
et al. (2015) discovered a magnetite–troilite assemblage in Apollo
samples. They inferred that there was a low-temperature equilibrium
with oxidizing agents (H2O or CO2) from exogenous fluid-bearing
impactors (carbonaceous chondrite or comets). This low temperature
(~500 °C) origin of magnetite under oxidizing hydrothermal condi-
tions has been used to explain formation of most magnetite in extra-
terrestrial samples, and it has been extensively studied by terrestrial
rock experiments2,10,28–32
. However, the magnetite found in this study
coexisted with metallic iron and iron-sulfide minerals. These phases
correspond to quite different oxygen fugacity conditions, and thus
C–H–O fluid alteration processes are not responsible for formation of
magnetite in the studied spherical iron-sulfide grains33
.
Magnetite–FeNi–iron sulfide assemblages have been found in
meteorites, which has been attributed to the high-pressure and high-
temperature conditions that allow them to coexist34,35
.
The main difference between our observations and the phenom-
ena reported in the studies mentioned above is that it is pure metallic
iron particles that coexisted with sub-microscopic magnetite in the
Chang’E-5 samples. This indicates another formation mechanism of
magnetite that is generally accepted in the field of hot-rolled steel
sheets, namely, co-precipitation of magnetite and metallic iron from
iron oxides by a eutectoid reaction28,36–38
. The eutectoid reaction can
be simply described as decomposition of metastable wüstite (FeO) to
magnetite (oxidized species) and metallic iron (reduced species) at a
relatively low temperature of ~570 °C39–41
.
The excess elemental Fe and O in the studied iron-sulfide grains,
as well as the volume of the vesicles was much less than the total
volume of pure-iron and magnetite particles within the iron-sulfide
grains, which suggest that a certain amount of FeO is dissolved within
iron-sulfide (FeS + 6FeO = SO2 + 4Fe + Fe3O4). The ellipsoidal shape,
large number of pores at the grain edges, and formation of pure
metallic iron all indicate that the studied spherical iron-sulfide grains
experienced high-temperature events.
Numerous observations and simulations of extraterrestrial sam-
ple have demonstrated that a considerable amount of non-siderophile
O components from the surrounding O-containing matrix can be
incorporated into the metal-sulfide phase and form Fe–S–O systems
under high-temperature conditions during impact processes35,42–44
.
Leroux et al. (2000) reported that the metal-sulfide globules embed-
ded in an amorphous silicate-glass matrix contained 13 wt% of FeO
under melting conditions, and the phase diagram showed that the
melting point of the Fe–S–O system decreases with addition of the O
component35,45
. Based on the oxygen content of the Chang’E-5 sphe-
rical iron-sulfide grains, thermodynamic calculations showed that the
~20% of dissolved FeO per mole of FeS in the iron-sulfide grain should
experience a temperature of above 915 °C (Supplementary Fig. 5).
Therefore, the studied Chang’E-5 spherical iron-sulfide grains under-
went melting and formed ellipsoidal grains.
The FeO–FeS phase diagram was used to constrain magnetite and
pure metallic iron particles formation within the spherical iron-sulfide
grains, yielding a eutectic temperature of α-Fe, magnetite, and pyr-
rhotite of below 600 °C (Supplementary Fig. 6). The magnetite and
pure metallic iron particles were commonly euhedral and entirely
embedded in the studied spherical iron-sulfide grains, showing that
they formed as solid-state precipitates at conditions below the melting
point46
. At the edges of the grains, there was no magnetite in equal
proportions to the pure-iron tentacles, suggesting a different reaction
process to that within the spherical iron-sulfide grains. Such massive
production of pure metallic iron accompanied by a large number of
pores can be interpreted as desulphurization of troilite (2FeS = 2Fe +
S2) or reduction of iron oxide and iron-sulfide to metallic iron
(2FeO + FeS = 3Fe + SO2)2,47
. The lunar vacuum conditions allow this
reaction to continue to outgas and lead to formation of large amounts
of pure iron wrapped around the grain edges. The scattered vesicles
within the grain can also be attributed to these reactions.
The absence of other molten phases attached to the spherical
iron-sulfide grains and the filamentous amorphous Si–Ca–S–O com-
position with a vesicular structure detected at the edge of the grain
suggest that the molten iron-sulfide droplets most likely interacted
with the silicate gas. The occurrence of vapor phase in lunar surface
conditions involved temperature far 2000 °C, which is indicative of
large-impact processes on the Moon47,48
. Furthermore, simultaneous
precipitation of magnetite and metallic iron within the Chang’E-5 iron-
Article https://doi.org/10.1038/s41467-022-35009-7
Nature Communications| (2022)13:7177 4
5. sulfide grains indicates the conditions for equilibrium crystallization.
Thus, the grains experienced an extremely high-temperature envir-
onment for a long duration, and such spherical iron-sulfide droplets
are more likely to be produced in oxygen-bearing gas columns formed
by large impacts47
.
Based on the above discussion, a plausible scenario for the com-
plex phenomenon within the spherical iron-sulfide grain is that the
molten iron-sulfide droplets reacted with the surrounding silicate
vapor during a large-impact event. During the melt stage of iron-sul-
fide, the surrounding FeO-gas component reacted with the edges of
the iron-sulfide droplets in a reduction reaction, forming a substantial
amount of iron tentacles around the grains, and some of the FeO gas
dissolved in the interior of the iron-sulfide droplets. During the sub-
sequent rapid-solidification process, the FeO dissolved inside the iron-
sulfide droplet decomposed to form sub-microscopic magnetite and
pure metallic iron particles.
The newly discovered spherical iron-sulfide grains in the Chang’E-
5 lunar fines contained sub-microscopic metallic iron and magnetite
particles, both of which are important ferromagnetic minerals with
magnetic susceptibilities of 20,000–110,000 and 50,000, respec-
tively, compared with 13–36 for troilite. Therefore, the eutectic reac-
tion that occurred within the iron-sulfide minerals during impact may
significantly improve the magnetic properties of the lunar crustal
materials16
.
Lunar magnetic anomalies have been a mystery since the Apollo
era, and their origin is still under debate12,13
. Orbiting magnetometer
data from Lunar Prospector suggests that magnetic anomalies may be
associated with impact basins on the Moon, especially because lunar
surface impact ejecta deposits are often strongly magnetized12,13,49
.
Generation of magnetic anomalies on the lunar surface mainly
depends on the content of ferromagnetic minerals in the lunar soil and
the strength of the external magnetic field, and stronger magnetic
properties can be recorded for greater degree of magnetization of the
lunar surface minerals15
. In addition to the existence of the lunar core
dynamo field (~3.9 Ga), impact processes have been demonstrated to
be a key pathway for magnetic field generation in the lunar crust13,50–52
.
However, formation and the distribution of ferromagnetic minerals
that can effectively contribute to the magnetic anomalies on the lunar
surface are still unclear, and it is difficult to link the magnetic prop-
erties of known endogenous lunar materials to lunar crustal anomalies
because of the ~2–4 order of magnitude weaker magnetic properties
relative to terrestrial materials15
.
Wieczorek et al. (2012) performed numerical simulations of
large-scale impacts. They found that chondritic projectile mate-
rials (Fe metal) from giant impacts can provide the highly ferro-
magnetic minerals to account for the intensity of the observed
magnetic anomalies, and the simulations were consistent with the
magnetic properties of distal ejecta from the South Pole–Aitken
basin formation event12
. Therefore, impact-related materials may
be the most plausible carriers of magnetic anomalies. It is well
known that the extremely high temperature and pressure condi-
tions provided by large impacts are necessarily accompanied by
significant material transformations53,54
. However, in addition to
ferromagnetic materials directly injected by the impactor (e.g.,
FeNi), newly formed ferromagnetic minerals during the large-
impact have not been considered. The results of this study of
Chang’E-5 lunar soil indicate that iron-sulfide minerals undergo
complex eutectic reactions during impacts to form highly ferro-
magnetic minerals (sub-microscopic magnetite and metallic iron),
which could also be an important source of ferromagnetic
material on the lunar surface. Considering that iron-sulfide is an
important component of chondritic meteorite projectiles, it is
highly likely that this reaction occurred during large impacts on
the lunar surface. Since the high magnetic susceptibilities of
magnetite and metallic iron, the impact process would greatly
reduce the thickness requirements of lunar soil for lunar mag-
netic anomalies, irrespective of whether the ferromagnetic
minerals are brought directly from the impactor body or such
reaction acts on iron-sulfide minerals12
.
We mapped the total magnetic field strength at the lunar
surface based on Kaguya and Lunar Prospector magnetometer
data. The Chang’E-5 landing site exhibits a relatively low intensity
with an estimated maximum magnetic field strength of 1.18 nT
(Supplementary Fig. 7)55,56
. Our observations showed that there
were very few spherical iron-sulfide grains in the Chang’E-5 lunar
fines, and only two magnetite-bearing spherical iron-sulfide grains
were found in the studied samples. We suggest that the two main
reasons for the weaker magnetic field strength in the Chang’E-5
region are as follows: (1) Lunar magnetic field anomalies are
spatially correlated with large-impact ejecta, but only a few dis-
tant ejecta from large-impact craters are mixed in the Chang’E-
5 sampling region23
. (2) Chang’E-5 lunar soil has a young age of
formation, and the possibility of the presence of an effective
external magnetic field (generated by ancient core dynamics or
basin-forming impacts) is relatively low.
Based on the above discussion, we conclude that the key factors
for generation of magnetic anomalies on the lunar surface are (1) the
presence of ferromagnetic minerals originating from large-impact
events, including projectile injection or impact-induced material
transformation, and (2) magnetization of the ferromagnetic minerals
in the presence of external magnetic fields (impact-related magnetic
fields or core dynamo fields). These formation conditions result in a
matching relationship between the magnetic anomaly distribution in
the lunar crust and the distal ejecta of large impacts.
Methods
Samples
The Cheng’E-5 samples examined in this study consisted of the fine
fractions of lunar regolith soils (CE5C0400YJFM00505 and
CE5C0200YJFM00302). The lunar soils were spread on silicon wafer
and covered with a gold film for the SEM observations.
SEM and transmission electron microscopy (TEM) analysis
The iron-sulfide grains were initially identified by backscatter electron
imaging, which showed a bright contrast, and they were confirmed by
EDX combined with field-emission SEM (FEI Scios) at the Institute of
Geochemistry, Chinese Academy of Sciences (CAS), Guiyang (Supple-
mentary Fig. 1). Observation of the nanophases within the focused-ion-
beam samples was performed by field-emission scanning TEM (200 kV,
FEI Talos F200X) at the Suzhou Institute of Nano-tech and Nano-bio-
nics, CAS. Chemical analysis of the focused-ion-beam foils was per-
formed by scanning TEM combined with energy-dispersive detection.
High-resolution TEM images and SAED patterns were acquired to
identify the nanocrystal structure.
Electron energy-loss spectroscopy (EELS) analysis
EELS spectra were employed to measure the oxidation state of Fe
in the nanocrystals. EELS analyses were performed using a Gatan
GIF Quantum ER System Model 965 parallel EELS spectrometer
attached to a Hitachi HF5000 aberration-corrected scanning
transmission electron microscope housed at the Shanghai Insti-
tute of Ceramics, CAS, operating at an accelerating voltage of
200 kV. We collected EELS spectra in DualEELS mode with a probe
current of 100 pA. The energy resolution was between 0.5 and
0.7 eV, as measured from the full width at half maximum height of
the zero-loss peak. The line profiles of EELS were acquired at
0.25 eV/channel dispersion with a dwell time of 18 s/point for O
and Fe, and the acquisition times were 10 s for the Fe and O point
analyses. Fayalite and hematite standards were prepared as Fe2+
and Fe3+
references to quantitatively calculate the Fe2+
/Fe3+
ratios
Article https://doi.org/10.1038/s41467-022-35009-7
Nature Communications| (2022)13:7177 5
6. of magnetite from the EELS spectra. The Fe-oxidation-state ratios
were quantified using the L3 edge, and the peak positions and full
widths at half maximum heights of the standards were used as
constraints for the fit. The Fe-oxidation-state ratios of magnetite
were determined by normalizing the best-fit weight, and the
goodness of fit was evaluated using the coefficient of determi-
nation. The spectra of magnetite with coefficients of determina-
tion of ~0.99 (with a value closer to 1 indicating a better fit) are
reported in our study.
Lunar magnetic field strength mapping
The data of the total field intensity on the lunar surface were derived
from the results of Tsunakawa et al. (2015) and Ravat et al. (2020)55,56
.
Originally, the magnetic field was obtained at altitudes of 10–45 km by
the Kaguya and Lunar Prospector missions. The surface components
were derived by surface-vector mapping in Tsunakawa et al. (2015) and
by L1-norm model regularization of the radial component at the sur-
face on the magnetic monopole bases and along-track magnetic field
differences in Ravat et al. (2020)55,56
.
Data availability
All data are available in the main text or the supplementary informa-
tion, and the original TEM and EELS data of this study are available in
Guo (2022)57
and online at https://data.mendeley.com/datasets/
nd2tc5bykb/1.
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Article https://doi.org/10.1038/s41467-022-35009-7
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