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Fast Radio Bursts Are Starting to Map the Universe’s Missing Gas

15 September 2026 at 16:00

A new Nature Astronomy study uses 114 fast radio bursts to trace cosmic gas and test how stellar and black-hole feedback reshapes matter around galaxies.

The post Fast Radio Bursts Are Starting to Map the Universe’s Missing Gas appeared first on Curiosmos.

Giant-nucleus cells emerge as early cancer markers in new study

11 September 2026 at 11:21

For more than four decades, pathologists have glimpsed something unsettling under the microscope in the earliest stages of certain cancers: cells with nuclei far larger than they should be, swollen and distorted, lurking in tissue that otherwise appears on the verge of catastrophe. These so-called giant-nucleus cells, or karyomegalic cells, were first spotted in the 1980s in animal experiments involving iron-induced oxidative stress, yet their biological identity and their role in the genesis of cancer remained stubbornly obscure. Now, a team of researchers in Japan has provided the most detailed portrait of these cells to date, and their findings suggest that the enormous nuclei may be far more than a curiosity—they could be the founding population of early cancer, visible before any tumor exists, and potentially useful as a predictor of patient outcomes.

The study, led by Shinya Toyokuni, professor emeritus at Nagoya University Graduate School of Medicine, together with assistant professor Yingyi Kong and colleagues, was published in Redox Biology. The work addresses a deceptively simple question: when iron overload kills most cells in a tissue through oxidative damage, who survives, and what do the survivors become? Iron is an essential micronutrient, but in excess it is a potent carcinogen. Its chemistry is both the reason we need it and the reason it can harm us. Iron catalyzes the formation of hydroxyl radicals from hydrogen peroxide through the Fenton reaction, and these radicals shred DNA, oxidize lipids, and damage proteins. When the damage is severe enough, a form of programmed cell death called ferroptosis is triggered—an iron-dependent demise characterized by lipid peroxidation cascades that rupture the cell membrane. Ferroptosis has become one of the hottest topics in cancer biology precisely because it links iron metabolism, oxidative stress, and cell fate in a single mechanism.

Toyokuni’s team reasoned that if ferroptosis sweeps through iron-damaged tissue, the cells that escape it must be exceptional in some way, and those exceptions might be the seed of malignancy. To find out, they turned to a well-established animal model in which ferric nitrilotriacetate, a carcinogenic iron compound, is injected into rats, delivering a bolus of iron to the kidneys. The compound accumulates in the proximal tubules, where it catalyzes oxidative damage and, over months, produces renal cell carcinoma. In the experiments, the researchers collected kidney tissue before the injection and again one and three weeks afterward. Crucially, they also included a second experimental group: rats carrying a single mutated copy of the BRCA1 gene, the same gene that, when mutated in humans, dramatically raises the risk of breast and ovarian cancers and is associated with renal carcinoma in certain contexts.

The methodological heart of the study lies in its marriage of two technologies. The first is spatial transcriptomics, a technique that maps gene activity across individual cells within a tissue section while preserving the tissue’s original architecture—so researchers can see not only which genes are active but where in the tissue those transcriptional programs are operating. The second is computational nuclear morphometry, which quantifies the size, shape, and density of cell nuclei in the same samples. By overlaying the two datasets, the team could link the physical appearance of each cell—above all, the size of its nucleus—to its underlying transcriptional state. This integration is important because morphological atypia has long been the currency of diagnostic pathology, but connecting that atypia to molecular signatures at single-cell resolution is a recent capability.

What emerged within a week of iron administration was striking. Giant-nucleus cells appeared in the damaged kidneys, and these cells were not simply wounded cells awaiting death. They showed elevated expression of potent oncogenes, including Myc and Met, and they had acquired resistance to ferroptosis—the very cell death pathway that was eliminating their neighbors. In other words, the extreme oxidative environment had functioned as a brutal selective pressure, and the cells best adapted to survive it had activated a program that resembles, in miniature, the hallmark machinery of cancer. The enrichment of Myc, a transcription factor that drives cell growth and proliferation, and Met, a receptor tyrosine kinase involved in invasive growth, paints a picture of cells that are not merely enduring damage but reorganizing themselves around it.

The BRCA1 connection proved equally consequential. BRCA1 is best known as a guardian of the genome, a scaffold for the homologous recombination machinery that repairs double-strand DNA breaks. In the BRCA1-mutant rats, giant-nucleus cells emerged with distinctly different biological profiles from those in wild-type animals. The interpretation the researchers offer is that BRCA1 deficiency cripples DNA repair, so more of the damaged cells that would otherwise die or be repaired instead survive in their injured, genome-compromised state—becoming precancerous giant-nucleus cells. Electron microscopy and cellular respiration measurements reinforced this idea at the subcellular level: cells from BRCA1-mutant rats showed mitochondrial remodeling, with impaired iron handling and compromised respiratory function. Mitochondria, long appreciated as power plants, are also central regulators of ferroptosis and iron metabolism, and their disarray in the mutant animals may be both a consequence of BRCA1 loss and a driver of the abnormal iron biology that feeds karyomegaly.

Using their combined gene-expression and nuclear-shape data, the researchers went further and classified the giant-nucleus cells into six distinct types. One type possessed extremely large nuclei and gene signatures of stress-induced growth arrest—cells that appear to have locked themselves into a senescent-like state, consistent with profiles reported in earlier studies. Another type, found more frequently in BRCA1-mutant kidneys, showed heightened activity of cancer-related genes alongside elongated nuclei, a combination the authors interpret as a potential precancerous state. The taxonomy matters because it reframes giant-nucleus cells from a single enigmatic category into a spectrum, some members of which may be harmless or even protective while others carry genuine malignant potential.

One of the most provocative findings concerns the cells surrounding the giants. Even morphologically normal cells near giant-nucleus cells exhibited gene expression changes that appear to promote survival, suggesting that the karyomegalic cells remodel their local microenvironment in ways that extend beyond their own borders. In BRCA1-mutant kidneys, the team also documented a substantial increase in stromal cells—non-cancerous supportive cells including immune and connective tissue elements—around the damaged regions. The local tissue environment, the tumor niche in the language of modern oncology, was being reshaped long before any tumor could be called a tumor. This raises the possibility that a single conspicuous cell, easily identified by its nucleus under a conventional microscope, could serve as a sentinel for a whole neighborhood of incipient malignancy.

The leap from rat kidneys to human medicine came through two complementary analyses. First, the researchers mined TCGA-KIRC, a large public database of kidney cancer patients, asking whether tumors carrying gene-expression patterns resembling the cancer-prone giant-nucleus cells were associated with different clinical trajectories. They were: patients whose tumors shared the gene patterns of the cancer-prone giant-nucleus cells had shorter survival times, while those with patterns resembling the healthier giant-nucleus cell types had better outcomes. Not all giant-nucleus cells, in other words, are created equal, and the transcriptional fingerprints defined in the rat model appear to carry prognostic weight in human disease. Second, in a small pilot study, the team examined breast tissue from seven individuals with inherited BRCA1 mutations and fifteen without, observing abnormal nuclear features similar to those in the animal model in the mutation carriers. While the sample size is modest, the parallel hints that karyomegaly may be a cross-tissue marker of BRCA1-linked precancerous change.

The broader implications run in two directions. Clinically, the promise is that giant-nucleus cells, being easy to spot under the microscope, could function as early indicators of cancer—visible warnings in tissue that would otherwise be classified as merely damaged or inflamed. The TCGA survival data suggest that their gene-expression signatures might even stratify patients by risk once a tumor has formed. Scientifically, the study offers a concrete mechanism connecting an environmental exposome factor—iron-catalyzed oxidative stress—to a defined, transcriptionally characterized precancerous population, with ferroptosis resistance as the pivot. It also implies testable therapeutic hypotheses: if blocking mitochondrial remodeling or reversing ferroptosis resistance could prevent the persistence of the precancerous cells, early intervention might stop cancer before it starts. Toyokuni and his colleagues are careful to note that long-term studies will be needed to determine how giant-nucleus cells actually progress into tumor cells, whether such interventions can work, and whether nuclear shape combined with gene patterns can be validated as a diagnostic in larger patient cohorts. But the central message is already legible: some of the earliest chapters of cancer may be written in cells that have grown too large to be ignored.

Subject of Research: Animals

Article Title: Iron-catalyzed oxidative stress reveals an exposome-related ferroptosis-resistant karyomegalic niche in BRCA1-linked renal carcinogenesis.

Article References: Kong, Y., Shiraki, Y., Furuhashi, K., Maruyama, S., Imaoka, T., Enomoto, A., & Toyokuni, S. (2026). Iron-catalyzed oxidative stress reveals an exposome-related ferroptosis-resistant karyomegalic niche in BRCA1-linked renal carcinogenesis. Redox Biology, 95, Article 104293. https://doi.org/10.1016/j.redox.2026.104293

Image Credits: AI Generated

DOI: 10.1016/j.redox.2026.104293

Keywords: giant-nucleus cells, karyomegaly, ferroptosis, BRCA1, iron-catalyzed oxidative stress, spatial transcriptomics, renal carcinogenesis, mitochondrial remodeling, nuclear morphometry, precancerous cells, TCGA-KIRC, Nagoya University

Unique zipper reaction converts perfluoroalkyl chains via defluorination and borylation

9 September 2026 at 17:22

In a development that could reshape how chemists recycle one of the most persistent classes of synthetic molecules ever made, researchers have reported a new catalytic strategy that strips fluorine atoms from perfluoroalkyl chains in a controlled, sequential fashion while installing a single boron group at the chain’s terminus. The work, published in Nature Communications, introduces what the authors call zipper polydefluorination-monoborylation, a transformation that walks down a perfluoroalkyl skeleton and removes multiple fluorine atoms in a stepwise cascade before capping the partially defluorinated product with a boron substituent. The achievement addresses a longstanding challenge in fluorine chemistry: while carbon-fluorine bonds are prized in materials and pharmaceuticals for their extraordinary stability, that same stability makes them notoriously difficult to break selectively, leaving chemists with few tools for converting perfluorinated waste streams into useful building blocks.

Perfluoroalkyl substances, often grouped under the umbrella of PFAS chemistry, owe their remarkable properties to the strength of the carbon-fluorine bond, which at roughly 485 kilojoules per mole in fully fluorinated chains ranks among the strongest single bonds that carbon forms. This bond strength, combined with the sheer electronegativity of fluorine, means that perfluoroalkyl groups resist oxidation, hydrolysis, and thermal degradation under nearly all conventional conditions. As a consequence, perfluorinated chains accumulate in the environment and resist standard degradation pathways, prompting intensive research into defluorination methods ranging from photocatalytic single-electron transfer to reductive hydrodefluorination with metal hydrides. Yet most existing approaches suffer from a common limitation: they either remove fluorine indiscriminately, collapsing the entire chain to a mixture of products, or they remove only a single fluorine atom, offering little control over the degree of defluorination. The new study demonstrates a way to achieve the best of both worlds, delivering multi-fluorine removal in a predictable pattern while simultaneously introducing a versatile functional handle.

The conceptual heart of the method lies in what the authors describe as a zipper mechanism. Rather than removing fluorine atoms at random positions along the chain, the reaction initiates at a defined site and then propagates along the perfluoroalkyl backbone one carbon at a time, much as a zipper opens tooth by tooth. At each step along the chain, a fluorine atom is expelled and replaced in sequence, with the reaction front advancing until a thermodynamic or kinetic stopping point is reached. The monoborylation component of the process ensures that once the zipper has run its course, the resulting olefinic or anionic intermediate is intercepted by a boron reagent, furnishing a product in which the boron group occupies a predictable position derived from the original perfluoroalkyl terminus. Organoboron compounds are among the most valuable intermediates in modern synthetic chemistry, serving as partners in Suzuki-Miyaura cross-coupling and as precursors to alcohols, amines, and halides, so their installation at a defluorination site effectively converts a chemical dead end into a synthetic launching pad.

Mechanistically, the transformation draws on the characteristic reactivity of organoboron reagents toward geminal difluoroalkenes, the partially defluorinated intermediates that arise when consecutive fluorine atoms are eliminated from a perfluoroalkyl chain. Perfluoroalkyl chains, when subjected to strong bases or reductive conditions, can undergo sequential beta-fluoride elimination events, each generating a more highly unsaturated species. The boron reagent in the reported system engages these unsaturated intermediates through addition pathways that install boron at the terminal carbon while generating a carbanionic center adjacent to the remaining difluoromethylene unit. That newly formed carbanion is perfectly positioned to expel another fluoride ion, regenerating an unsaturated handle one carbon further down the chain and setting up the next iteration of the cycle. This intimate coupling of borylation and defluorination is what gives the reaction its chain-walking character: each borylation event creates the conditions for the next defluorination event, and the process ripples along the chain until the fluorine reservoir is exhausted or the reagents are consumed.

The practical significance of the work becomes apparent when one considers the fate of the fluorine atoms themselves. In the zipper process, fluorine is released as fluoride ion, which under the reaction conditions is sequestered by silicon-containing trapping agents to form robust silicon-fluorine bonds. Fluorosilicates of this kind are stable, isolable, and, importantly, compatible with industrial processes for recycling fluorine back into hydrofluoric acid, the feedstock from which essentially all synthetic organofluorine compounds are made. In this sense, the method does more than transform perfluoroalkyl chains into borylated products; it also lays the groundwork for closing the fluorine cycle, recovering the fluorine content of persistent molecules in a form that can be fed back into the chemical economy. With global concern over PFAS contamination intensifying and regulatory pressure on fluorinated chemicals mounting, technologies that enable fluorine recovery rather than dilution into the environment carry considerable weight.

From a synthetic chemistry standpoint, the products of the reaction open multiple downstream avenues. Because the boron substituent is installed at a defined position on a partially fluorinated alkyl or alkenyl framework, the resulting molecules retain a programmable mixture of carbon-fluorine bonds and carbon-boron functionality. The remaining fluorine atoms can tune the lipophilicity, metabolic stability, and dipole moment of the scaffold, properties that are actively exploited in medicinal chemistry when designing fluorinated drug candidates. Meanwhile, the boron group serves as a convertible handle, allowing the defluorinated carbon center to be joined to aromatic rings through cross-coupling, oxidized to alcohols, or aminated in homologation reactions. In effect, the method converts a chemically inert perfluoroalkyl group, useful mainly as a passive coating or tail, into a functionalized partial-fluoro skeleton that can participate in the full toolkit of carbon-carbon and carbon-heteroatom bond formation.

The reported study also sheds light on the factors governing how far the zipper travels along a given chain. Chain length, the nature of the substituent anchoring the perfluoroalkyl group, and the stoichiometry of the base and boron reagent all influence the number of fluorine atoms removed and the distribution of products obtained. Through systematic variation of these parameters and careful analysis of the reaction mixtures by nuclear magnetic resonance spectroscopy and mass spectrometry, the authors map out the scope of the transformation across a range of perfluoroalkyl substrates, from short perfluoroethyl groups to longer chains approaching those found in commercial fluorosurfactants. Control experiments interrogating individual elementary steps support the proposed sequential elimination-addition mechanism and rule out alternative pathways involving radical fragmentation or random beta-scission, underscoring the unusually high degree of positional control the method achieves.

Beyond its immediate synthetic utility, the work contributes to a growing body of research aimed at taming the carbon-fluorine bond through the strategy of defluorinative functionalization. Over the past decade, chemists have developed an impressive repertoire of reactions that replace fluorine in perfluoroalkyl and fluoroarene substrates with groups ranging from hydrogen to sulfur, nitrogen, and carbon substituents. What distinguishes the zipper approach is its multiplicity and its directionality: instead of a single substitution event at a single site, the reaction performs many substitutions in a choreographed sequence along a chain, effectively treating the perfluoroalkyl group as a one-dimensional lattice to be patterned at will. This conceptual reframing, from defluorination as bond-breaking to defluorination as programmable editing, may inspire analogous strategies for other polyfluorinated motifs, including perfluoroarenes and perfluoropolyethers, two additional classes of highly persistent fluorinated materials.

Challenges remain before such chemistry can move from the laboratory bench to environmental remediation at scale. The reaction conditions reported rely on strong bases and moisture-sensitive boron reagents handled under inert atmosphere, and the substrates studied are discrete, soluble perfluoroalkyl compounds rather than the polymeric or adsorbed PFAS species that dominate environmental contamination. Scaling the chemistry will require sourcing boron reagents economically, managing the large quantities of fluoride generated, and integrating the transformation with upstream methods for extracting perfluoroalkyl pollutants from water and soil. Nevertheless, the demonstration that a perfluoroalkyl chain can be unzipped in a controlled manner, with fluorine captured in recyclable form and a valuable boron handle installed, establishes a credible chemical pathway toward defluorination that is both productive and selective, a combination that has eluded the field for decades.

As policymakers and scientists grapple with the legacy of fluorine chemistry, work of this kind illustrates a middle path between the wholesale abandonment of fluorinated molecules and their indefinite persistence in the biosphere. The fluorine atom confers properties that industry and medicine continue to depend upon, and the ability to disassemble fluorinated architectures on demand, recovering both the carbon skeleton as a functionalized building block and the fluorine content as a recyclable salt, points toward a more circular future for organofluorine chemistry. The zipper polydefluorination-monoborylation strategy reported in Nature Communications is an early but striking example of that vision made concrete at the molecular level, and it is likely to prompt rapid efforts to extend the concept across the breadth of persistent fluorinated chemicals.

Subject of Research: Controlled sequential defluorination of perfluoroalkyl chains coupled with terminal borylation (zipper polydefluorination-monoborylation)

Article Title: Zipper polydefluorination-monoborylation of perfluoroalkyl chains

Article References: Albers, S. L., Harzendorf, J. K., Deliaval, M., Köllmann, J., & Streuff, J. (2026). Zipper polydefluorination-monoborylation of perfluoroalkyl chains. Nature Communications, 17(1), Article 9502. https://doi.org/10.1038/s41467-026-77437-9

Image Credits: AI Generated

DOI: 10.1038/s41467-026-77437-9

Keywords: perfluoroalkyl chains, defluorination, polydefluorinative borylation, organoboron compounds, carbon-fluorine bond activation, PFAS degradation, fluorine recycling, geminal difluoroalkenes, cross-coupling, sustainable chemistry

Earth May Not Be a Cosmic Fluke, New Simulations Suggest

9 September 2026 at 16:03
Exoplanet Ross 128 b Is Not Like EarthSolar system simulations starting from varied initial conditions suggest that Earth-like planets can emerge naturally from planet formation. Computer simulations of planetary systems can now begin from thousands of different starting conditions, allowing researchers to explore how worlds might emerge without assuming the final outcome. Over the past three decades, these models have advanced from [...]

IA et devoirs : cette peur pousse des parents à payer, même lorsqu’ils doutent de ses bénéfices

8 September 2026 at 04:27
Avec l’intelligence artificielle qui s’invite désormais dans les devoirs des collégiens et lycéens, de nombreuses familles font face à un dilemme : faut-il en limiter l’usage ou, au contraire, permettre à son enfant de suivre le mouvement ? Une étude révèle à quel point les pratiques des autres...

Hubble Spots ‘Superbubble’ in Large Magellanic Cloud

7 September 2026 at 20:02
This Hubble image shows the emission nebula LHA 120-N44. Image credit: NASA / ESA / Hubble / D. Gouliermis.

A new images from the NASA/ESA Hubble Space Telescope reveals LHA 120-N44, a striking nebula located roughly 160,000 light-years away in the Large Magellanic Cloud, a satellite galaxy of the Milky Way.

The post Hubble Spots ‘Superbubble’ in Large Magellanic Cloud appeared first on Sci.News: Breaking Science News.

Why digital transformations still fail

4 September 2026 at 10:00

The consulting firms told us this would be different. They arrived with slick slide decks, expensive vendor packages, and promises to revolutionize how we do business. Their message was clear: Digital transformation was no longer optional; it was existential. Companies that failed to adapt would be left behind and crushed by more agile competitors with cloud-native architecture and data-driven strategies.

That was back in 2020, when Boston Consulting Group released research showing that 70% of digital transformations failed to meet their objectives. The consulting industry rushed to publish its frameworks, maturity models, and proprietary methodologies. Enterprise IT organizations spent millions on these programs, hoping to finally bridge the gap between technological capability and business value.

Several years on, I can say that little has changed. If anything, the issue has worsened.

The damage that was done

Most digital transformations didn’t just fail to deliver ROI; they actively damaged the organizations that undertook them. Technical debt accumulated as companies deployed monolithic cloud platforms that were neither modular nor scalable. Business misalignment became endemic as transformations focused on technology for its own sake rather than on solving actual business problems. Organizations found themselves locked into expensive vendor relationships that failed to deliver on their promises.

I’ve spoken with dozens of enterprise CIOs and CTOs over the past several years, and the stories are remarkably consistent. Transformations that were supposed to take six months stretched to two years. Budgets estimated at a few million exploded to six, eight, even twelve times the original projection. The consulting firms had excellent PowerPoint skills, but when it came to implementation, the results were consistently disappointing.

The damage wasn’t just financial. Organizations lost confidence in their IT capabilities. Talented people left because they were tired of being managed by consultants who couldn’t code their way out of a paper bag. Business stakeholders grew cynical about technology initiatives, having been burned too often by projects that promised transformation but delivered chaos.

Why the consulting models failed

Let’s be direct about what happened. The consulting industry discovered that digital transformation was highly profitable. They could sell their methodologies, vendor partnerships, and “best practices” frameworks, and charge premium fees for implementation support. The problem was that these frameworks were largely one-size-fits-all approaches disguised as bespoke solutions.

A major global bank doesn’t have the same requirements as a regional healthcare provider, yet both were sold the same transformation playbook. The consulting firms had invested too heavily in their methodologies to admit that the real answer might be to start with business requirements and work backward toward technology. Instead, they assembled prepackaged solutions optimized for vendor partnerships rather than clients’ actual needs.

The talent problem was equally severe. The consulting firms could certainly talk about digital transformation; they had excellent slides and compelling narratives. But when it came to implementation, the skill gaps were glaring. These organizations assembled solutions by following playbooks rather than understanding how the technology components actually fit together. The result was systems that were overengineered, overprovisioned, and ultimately underperforming.

Cloud computing was supposed to be the great enabler, but many organizations misunderstood and misapplied it. Organizations lifted and shifted their existing problems along with their existing architecture. Monolithic applications running on expensive virtual machines became the new normal, with organizations paying cloud costs that far exceeded their on-premises expenses, yet achieving none of the scalability benefits the cloud was supposed to deliver.

What we still need to learn

As we grapple with the next wave of technology transformation—this time centered on artificial intelligence—the lessons from digital transformation failures should be front and center. The first and most important lesson is brutally simple: Focus on business needs first. I know this sounds obvious, but I guarantee you that every failed digital transformation project lost sight of its core business requirements. They built technology for technology’s sake without understanding the problems they were trying to solve.

Too many transformations focused on individual business units rather than enterprisewide strategies. The result was a collection of systems that couldn’t work together cohesively. Isolated solutions felt like progress but actually made integration harder and created new dependencies that hadn’t existed before.

Organizations also need to invest in serious training for their people. I’m not talking about sending IT staff to vendor certification programs that teach them to pass tests on proprietary platforms. I mean fundamental architectural education that helps people understand how to assemble technology effectively.

We face a massive shortage of AI, cloud, and security architects, as well as other technical leaders who can design solutions that work. Rather than addressing this gap, organizations are placing unqualified people in these roles and hoping for the best. It’s past time to invest in education.

The case for simplicity

Here’s something that also should be obvious but clearly isn’t: You can solve the same business problem with $1 million or $20 million, depending on the sophistication of the IT organization building the solution. Both designs will work reasonably well, but one solution costs 20 times more because it is overbuilt and overengineered.

Organizations are adding AI to everything under the sun, even when simpler solutions would work just as well. They’re overprovisioning cloud resources because they lack the architectural discipline to rightsize their infrastructure. They’re building systems designed for scale they’ll never reach, complexity they don’t need, and features no one requested.

The path forward requires a minimalist approach. Build systems that are good enough for their intended purpose. Focus on requirements rather than capabilities. Resist the temptation to adopt every new technology just because it’s available.

Digital transformation didn’t fail because the technology was flawed. It failed because we forgot that technology exists to serve the business, not the other way around. To succeed with AI, we need to remember that fundamental truth. And remember the consulting industry’s tendency to sell us expensive solutions to problems we don’t have.

Why is Earth’s crust layered?

3 September 2026 at 12:00

Since the formation of the Earth 4.2 billion years ago, hot rock from the interior of the planet has cooled off and developed crystals that accumulated over millions of years, forming surface rocks with a layered composition, referred to as continental crust. Geologic evidence of how continental crust formed comes from large, ancient crustal blocks, called cratons. Cratons have existed for billions of years and form the cores of continents. 

Scientists have shown that the upper 10 to 15 kilometers (6 to 9 miles) of continental crust contains high concentrations of elements like uranium and thorium that decay and release heat over time, referred to as radiogenic elements. However, the lower 20 kilometers (12 miles) of crust has very few radiogenic elements. The cause of this planetary-scale differentiation is highly questioned, as geoscientists don’t know what formation processes could produce this unique characteristic. 

Earlier researchers suggested that changes in the concentration of radiogenic elements could occur when tectonic plates collide. Plate collision induces temperatures in the lower crust high enough to melt minerals that contain uranium and thorium, like zircon and monazite. The newly melted minerals form magma, which then rises and crystallizes in the upper crust. To test whether this process formed the layered continental crust, researchers Andrew J. Smye and Peter B. Keleman incorporated geochemical data from studies worldwide into a mathematical model comparing how concentrations of radiogenic elements vary under different temperatures. 

The team separated their global analyses into 2 categories of rocks that were buried deep in the crust and subjected to intense pressures and temperatures, via a process known as metamorphism. The first category included rocks formed from the accumulation of eroded grains buried in the deep crust that are subjected to high pressures and temperatures, called metasedimentary rocks. The second category included rocks formed when magma rises from the deep Earth and solidifies before experiencing high pressures and temperatures, called metaigneous rocks.

The researchers analyzed 3 subcategories from each of the 2 types of deep-crustal rocks. The first was rocks that experienced no intense pressure or temperature, the second was rocks subjected to 650 to 900°C (about 1,200 to 1,650°F), and the third was rocks subjected to 900 to 1,100°C (about 1,650 to 2,000°F). The researchers modeled the geochemistry of the 3 rock types at different temperatures to determine whether ultra-high-temperature metamorphism could cause crustal differentiation of radiogenic elements.

Smye and Keleman found that monazite doesn’t melt in either metasedimentary or metaigneous rocks at temperatures below 900°C, as indicated by the relatively high thorium content in these deep-crustal rocks. Alternatively, they found that above 900°C, uranium and thorium concentrations decreased in metasedimentary rocks, suggesting that minerals like zircon and monazite were melting. The melted minerals enter magma and rise into the upper crust, leaving behind metasedimentary rocks depleted in radiogenic elements by around 0.10 ppm.  

The team concluded that the enrichment of uranium and thorium in the upper continental crust requires temperatures greater than 900°C to initiate the melting of zircon and monazite in the lower crust. Temperatures above 900°C are linked to the movement and collision of continental plates. This result suggests that evidence of Earth’s differentiation has been preserved for more than 3 billion years, spanning most of the planet’s geological history. Since stable continental crust formed, uranium and thorium enrichment in the upper crust has consistently recorded layering produced by ultra-high temperature metamorphism.

The post Why is Earth’s crust layered? appeared first on Sciworthy.

Primordial Planetesimals from the Guts of Population III Stars

2 September 2026 at 21:45

Protoplanetary Disk

While previous investigations of planet formation across the universe’s history suggest that planets trickled into the picture, a recent study has found that primordial planetesimals could have formed much earlier from the insides of the first stars in the universe.

First Stars, First Planets?

When the first stars flickered on, the universe was filled with pristine gas, containing only hydrogen, helium, and a little lithium. This gas, though great at making massive stars known as Population III (Pop III) stars, was not yet enriched with the heavy elements necessary for planet formation and, of course, life. Past studies have suggested that planet formation in the universe was gradual, taking several billion years to peak after billions of stars created and spilled the needed metals into the universe. However, local pockets of enriched gas from Pop III stars could have created the right conditions for planet formation earlier in the universe’s history.

Pop III stars burned bright and fast, exploding violently in pair-instability supernovae that completely shredded the progenitor, ejecting over 100 solar masses of metals into their previously pristine surroundings. Cosmological simulations suggest that oxygen from these supernovae could have produced significant water fractions within the dense cores of the supernova remnant. This may have set the stage for planet formation in water-rich disks around subsequent generations of stars as early as 150–200 million years after the Big Bang — does numerical modeling support this planet formation hypothesis?

Protoplanetary disk growth

Simulation snapshots showing the formation and evolution of the protoplanetary disk for 13, 21, 30, 40, 50, and 60 thousands of years after protostellar birth. Click to enlarge. [Modified from Vorobyov et al 2026]

Primordial Planetesimals in Simulated Water-Rich Disks

To test if these water-rich dense cores within Pop III supernova remnants could form planetesimals, the building blocks of terrestrial planets, Eduard I. Vorobyov (University of Innsbruck; Southern Federal University) and collaborators performed numerical simulations tracing the collapse of one such gas core into a protoplanetary disk around a protostar. The simulations begin from the gravitational collapse of a 1-solar-mass gas cloud core, with a protostar emerging 24 thousand years after the initial cloud collapse. As the protostar’s gravity pulled in material from its surroundings, a rotating disk formed around the growing star.

Protoplanetary disk evolution and planetesimal growth

Simulation snapshot 40 thousand years after the formation of the protostar showing the gas, dust, and planetesimal surface densities and the dust-to-gas ratio. Click to enlarge. [Modified from Vorobyov et al 2026]

Tracking the gas and dust evolution in the disk, the authors found that several Earth masses of planetesimals formed within 0.5–1.0 au of the 0.4-solar-mass protostar. While the simulations did not trace the disk all the way to planet formation (this requires complex multi-body modeling and lots of computing power), enough planetesimals formed to create a Mars- or Earth-mass planet in the future. Luckily, unlike their live-fast and die-young predecessors, low-mass stars born from Pop III supernova remnants would still be burning hydrogen in their cores today, and ancient metal-poor stars in the Milky Way’s halo may be home to the universe’s first planets that could be detected in future exoplanet surveys. This study showed, for the first time, that water-rich protoplanetary disks with planetesimals could pop up billions of years earlier than previously thought, changing our understanding of planet formation in the universe.

Citation

“Planet Formation at Cosmic Dawn: Planetesimals in H2O-rich Disks around Low-mass Stars,” Eduard I. Vorobyov et al 2026 ApJL 1007 L51. doi:10.3847/2041-8213/ae907c

The post Primordial Planetesimals from the Guts of Population III Stars appeared first on AAS Nova.

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