Category: 7. Science

  • Prospects Of Detecting Rotational Flatness Of Exoplanets From Space-based Photometry

    Prospects Of Detecting Rotational Flatness Of Exoplanets From Space-based Photometry

    Accuracy of the retrieved oblateness parameter in the light curve which included red noise, for all eight σw noise levels. Squares in the input f–ϑ grid are coloured based on the accuracy of the fitted f: purple if the retrieved parameter is within 0.02 of the injected value, blue if it is within 0.04, orange when it is within 0.06, and red otherwise. Shading is present when no significant detection of oblateness is made (i.e. when there is no 3σ detection of f). — astro-ph.EP

    In the era of photometry with space-based telescopes, such as CHEOPS (CHaracterizing ExOPlanets Satellite), JWST (James Webb Space Telescope), PLATO (PLAnetary Transits and Oscillations of stars), and ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey), the road has opened for detecting subtle distortions in exoplanet transit light curves — resulting from their non-spherical shape.

    We investigate the prospects of retrieval of rotational flatness (oblateness) of exoplanets at various noise levels. We present a novel method for calculating the transit light curves based on the Gauss-Legendre quadrature. We compare it in the non-rotating limit to the available analytical models.

    We conduct injection-and-retrieval tests to assess the precision and accuracy of the retrievable oblateness values. We find that the light curve calculation technique is about 25% faster than a well-known analytical counterpart, while still being precise enough.

    We show that a 3σ oblateness detection is possible for a planet orbiting bright enough stars, by exploiting a precise estimate on the stellar density obtained e.g. from asteroseismology. We also show that for noise levels ≥256 ppm (expressed as point-to-point scatter with a 60~s exposure time) detection of planetary oblateness is not reliable.

    Sz. Kálmán, Sz. Csizmadia, L. M. Bernabó, R. Szabó, Gy. M. Szabó

    Comments: Provisionally accepted for publication in PASP on 18/07/2025. 23 pages, 17 figures
    Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
    Cite as: arXiv:2507.15359 [astro-ph.EP] (or arXiv:2507.15359v1 [astro-ph.EP] for this version)
    https://doi.org/10.48550/arXiv.2507.15359
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    Submission history
    From: Szilárd Kálmán
    [v1] Mon, 21 Jul 2025 08:10:49 UTC (2,197 KB)
    https://arxiv.org/abs/2507.15359
    Astrobiology, exoplanet,

    Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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  • Crew Dragon spaceship carrying Roscosmos cosmonaut to arrive at ISS on Aug 2 – NASA – Interfax

    1. Crew Dragon spaceship carrying Roscosmos cosmonaut to arrive at ISS on Aug 2 – NASA  Interfax
    2. NASA Sets Coverage for Agency’s SpaceX Crew-11 Launch, Docking  NASA (.gov)
    3. CREW-11 ARRIVES AT KENNEDY SPACE CENTER, July 26, 2025, KSC, 1:00 pm ET  Space Policy Online
    4. Meet the SpaceX Crew-11 astronauts launching to the ISS on July 31  Space
    5. The Crew-11 mission is due to launch no earlier than Thursday  The Daily Jagran

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  • World’s simplest artificial cell capable of chemical navigation unveiled

    World’s simplest artificial cell capable of chemical navigation unveiled

    Researchers have successfully built the simplest artificial cell ever that can navigate using chemicals, much like living cells do.

    Chemotaxis is the essential navigation system cells use to find their way, whether it’s bacteria seeking food or white blood cells moving to fight an infection.

    Researchers at the Institute for Bioengineering of Catalonia (IBEC) have shown how to program tiny bubbles to follow chemical trails.

    The study details the creation of a “minimal cell” that’s essentially a tiny lipid vesicle (a microscopic bubble). 

    What makes it special is that it encapsulates enzymes and can propel itself using chemotaxis, meaning it actively moves in response to chemical signals.

    These lipid vesicles can be programmed to move towards specific substances, mimicking how living cells like bacteria, white blood cells, and even sperm navigate.

    ‘What we find particularly fascinating is that this type of directed movement can occur even without the complex machinery typically involved, such as flagella or intricate signalling pathways. By recreating it in a minimal synthetic system, we aim to uncover the core principles that make such movement possible,” explained Bárbara Borges Fernandes, a PhD student, and study’s first author.

    Artificial cell movement

    To accomplish their goal, the researchers observed how cell-like vesicles moved when exposed to varying concentrations of glucose and urea.

    They placed either glucose oxidase or urease enzymes inside liposomes (lipid-based vesicles) to transform these substances into their final products. 

    A crucial step was adding a membrane pore protein to the liposomes. 

    The enzymes convert specific substances, while the pores act as channels for exchange. 

    Imagine the liposome as a boat. The pore and the enzyme act as its engine and navigation system, propelling it precisely toward its destination.

    This active motion relies on “breaking symmetry.”

    Trapping enzymes inside the vesicle and using pores to swap chemicals creates an uneven concentration around the particle.

    This slight imbalance then generates a fluid flow that propels the vesicle in a specific direction.

    The IBEC team carefully analyzed over 10,000 vesicles. 

    What they found was remarkable: as the number of pores increased, the artificial cells showed a stronger chemotactic response, moving directly towards higher concentrations of the desired substances.

    Understanding cell functioning

    Professor Battaglia emphasizes that by simplifying biological systems, like building an artificial cell with just a fatty shell, one enzyme, and a pore, researchers can uncover the fundamental principles of cellular communication and transport. 

    He sees this minimalist approach, inherent to synthetic biology, as a way to reveal the elegant, underlying chemistry that drives complex biological processes. 

    “These synthetic cells are like blueprints for nature’s navigation system. Build simple, understand profoundly,” said Battaglia, ICREA Research Professor at IBEC, Principal Investigator of the Molecular Bionics Group, and leader of the study. 

    The study is not just a scientific curiosity. 

    The ability to engineer artificial cells provides insights into how early, simple cellular units might have evolved into the complex life forms we see today.

    The findings were published in the journal Science Advances

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  • Neanderthals were not ‘hypercarnivores’ and feasted on maggots, scientists say | Science

    Neanderthals were not ‘hypercarnivores’ and feasted on maggots, scientists say | Science

    For hungry Neanderthals, there was more on the menu than wild mammals, roasted pigeon, seafood and plants. Chemical signatures in the ancient bones point to a nutritious and somewhat inevitable side dish: handfuls of fresh maggots.

    The theory from US researchers undermines previous thinking that Neanderthals were “hypercarnivores” who stood at the top of the food chain with cave lions, sabre-toothed tigers and other beasts that consumed impressive quantities of meat.

    Rather than feasting on endless mammoth steaks, they stored their kills for months, the scientists believe, favouring the fatty parts over lean meat, and the maggots that riddled the putrefying carcasses.

    “Neanderthals were not hypercarnivores, their diet was different,” said John Speth, professor emeritus of anthropology at the University of Michigan. “It’s likely maggots were a major food.”

    Neanderthals were thought to be top of the food chain because of the high levels of heavy nitrogen in their bones. Nitrogen builds up in living organisms when they metabolise protein in their food. A lighter form of the element, nitrogen-14, is excreted more readily than the heavier form, nitrogen-15. As a result, heavy nitrogen builds up in organisms with each step up the food chain, from plants to herbivores to carnivores.

    While the levels of heavy nitrogen in Neanderthal bones place them at the top of the food chain, they would not have been able to handle the amount of meat needed to reach those levels, the researchers say.

    “Humans can only tolerate up to about 4 grams of protein per kilogram of body weight, whereas animals like lions can tolerate anywhere from two to four times that much protein safely,” said Speth.

    Since many Indigenous groups around the world routinely consume maggots in putrefied meat, the researchers decided to explore their potential role. The experiments were not for the squeamish.

    Dr Melanie Beasley, a member of the team at Purdue University in Indiana, was formerly at the Forensic Anthropology Center, or Body Farm, at the University of Tennessee. There, researchers study donated human corpses that are left to decompose. The work helps forensic scientists hone their techniques, for example, to ascertain for how long people have been dead.

    Beasley measured heavy nitrogen in putrefying muscle and the maggots that infested the corpses. Heavy nitrogen rose slightly as muscle putrefied, but was far higher in the maggots. The same process would have occurred in carcasses the Neanderthals stored, Beasley said.

    The finding, reported in Science Advances, suggests that rather than consuming meat as ravenously as lions and other hypercarnivores, Neanderthals acquired high levels of heavy nitrogen by eating maggots, which themselves were enriched with heavy nitrogen.

    “The only reason this is surprising is that it contradicts what we westerners think of as food,” said Karen Hardy, professor of prehistoric archaeology at the University of Glasgow. “Elsewhere in the world, a very wide range of things are eaten, and maggots are a great source of protein, fat and essential amino acids.”

    “It is a no brainer for Neanderthals,” she added. “Put out a bit of meat, leave it for a few days then go back and harvest your maggots, its a very easy way to get good nutritious food.”

    “How does it shift our thinking? The Neanderthals as top carnivores was nonsense, it was physiologically impossible. So this makes sense, but also explains these high nitrogen signals in a way that nothing else has done so clearly,” Hardy said.

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  • Controversial ‘arsenic life’ paper retracted from Science

    Controversial ‘arsenic life’ paper retracted from Science

     

    After almost 15 years, the influential scholarly journal Science has retracted a controversial paper about the discovery of a microbe able to use arsenic instead of phosphorous in its biochemical processes (Science 2010, DOI: 10.1126/science.1197258).

    In the retraction notice, H. Holden Thorp, Science’s editor in chief since 2019, states that the paper is being retracted on the basis that the “reported experiments do not support its key conclusions” but not because of any deliberate fraud or misconduct.

    The retraction is accompanied by a letter from the authors disagreeing with the decision, stating, “While our work could have been written and discussed more carefully, we stand by the data as reported.”

    In the original paper, the authors describe an extremophile microbe called GFAJ-1 that they believe has the ability to weave arsenic into its proteins and nucleic acids to compensate for a lack of phosphorus. Confirming that arsenic can be incorporated into DNA has the potential to expand the chemical understanding of life on Earth—and beyond, an aspect that NASA and the journal initially played up.

    The paper immediately garnered harsh criticism from the scientific community over the researchers’ methods and conclusions. In 2012, Science published two papers from independent teams who were unable to replicate the original paper’s results.

    The current consensus is that although GFAJ-1 is unusually good at growing in high concentrations of toxic arsenic, sufficient evidence hasn’t been found that it actually incorporates arsenic into its DNA, and the bacterium likely survives by scavenging trace phosphorus from its surroundings. The authors say in their letter that these follow-ups didn’t adequately reproduce their original growth conditions for GFAJ-1.

    Back in 2012, Science’s policy was to retract papers only in cases of misconduct, which this is not. But, Thorp says, “The expectations for straightening out the literature have risen significantly,” and calls for the paper to be retracted have simmered throughout his tenure at the journal.

    The tipping point was a New York Times profile of Felisa Wolfe-Simon, the paper’s outspoken first author, that was published in February 2025. Thorp went on the record in that article saying he thought the paper should be retracted.

    According to guidelines from the Committee on Publication Ethics (COPE), “Retraction is a mechanism for correcting the literature and alerting readers to articles that contain such seriously flawed or erroneous content or data that their findings and conclusions cannot be relied upon. Unreliable content or data may result from honest error, naïve mistakes, or research misconduct.”

    Science’s current retraction policy states, “An accumulation of errors identified in a paper may cause the editors to lose confidence in the integrity of the data presentation, and the paper may be retracted.”

    Ariel Anbar of Arizona State University, one of the original paper’s authors, says the uncertainty in the data is “larger than one would like,” but “we don’t think there was a major error” that warrants retraction.

    Anbar says Thorp asked Wolfe-Simon to voluntarily retract the paper last fall, after he was contacted by the New York Times. She refused. After months of negotiations, the researchers and journal editors reached a compromise: The paper would be retracted with language that both parties agreed on. The researchers could voice their dissent in a letter.

    In addition to posting the retraction notice, Thorp and Science’s executive editor, Valda Vinson, published a blog post in which they expand on their reasons for retracting the paper. In the post, they reiterate that the decision is rooted in experimental error and “at no point has there been any discussion or suggestion at Science of research misconduct or fraud by any of the authors.”

    Thorp says he hopes that retracting the paper will put a period on the whole affair. “I hope this is the end of it,” he says.

    Anbar says he and his coauthors asked to see the blog post ahead of time, and the journal didn’t respond; they received a copy from a reporter. The post brings up critiques beyond what went into the notice, which Anbar says undermines the good-faith commitment to transparency that the authors and editors made when negotiating the retraction.

    One thing both Anbar and Thorp appear to agree on—although for different reasons—is wishing that arsenic life hadn’t whipped up such a firestorm in the first place.

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  • Building blocks of life may be far more common in space than we thought, study claims

    Building blocks of life may be far more common in space than we thought, study claims

    Astronomers have discovered key components to life’s building blocks swirling around a remote baby star, hinting that the stuff of life is far more prevalent throughout the universe than once thought.

    The material, discovered circling the protostar V883 Orionis 1,300 light-years from Earth in the constellation Orion, consists of 17 complex organic molecules that include ethylene glycol and glycolonitrile — precursors to components found in DNA and RNA.

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  • A Visitor from Beyond the Solar System

    A Visitor from Beyond the Solar System

    On July 02, 2025, astronomers confirmed the discovery of Comet 3I/ATLAS, marking only the third time in recorded history that an interstellar object (ISO) has been identified passing through our Solar System. This follows the landmark discoveries of 1I/‘Oumuamua in 2017 and 2I/Borisov in 2019.

    The confirmation was discussed during a SETI Live broadcast hosted by Dr. Simon Steel, Deputy Director of the Carl Sagan Center at the SETI Institute, and featured expert commentary from University of Washington astronomer Dr. James Davenport, SETI Institute postdoctoral fellow and comet researcher Dr. Ariel Graykowski, and SETI Chair and Allen Telescope Array Project Scientist Dr. Wael Farah.

    Discovery by the ATLAS Survey

    Comet 3I/ATLAS was first identified by the Asteroid Terrestrial-impact Last Alert System (ATLAS), a global network of four robotic telescopes located in Hawaii, Chile, and South Africa. ATLAS systematically surveys nearly the entire night sky every 24 hours, primarily searching for near-Earth objects that could pose a risk of impact.

    Initially, 3I/ATLAS appeared as a faint, fast-moving point of light. However, follow-up observations revealed the object was traveling at a hyperbolic velocity, meaning its speed and trajectory exceeded the Sun’s gravitational binding energy. This is characteristic of interstellar objects on open-ended orbits, distinguishing them from the typical elliptical orbits of bodies in the Solar System.

    Cometary Activity Detected: A Distinctive Feature

    Unlike 1I/‘Oumuamua, which lacked any visible comet-like features, 3I/ATLAS has displayed clear cometary activity, even while still four astronomical units (AU) from the Sun (one AU is the average distance between Earth and the Sun), making 3I/ATLAS more similar to 2I/Borisov in that regard.

    According to Dr. Graykowski, this activity manifests as a coma: a diffuse envelope of gas and dust created by the sublimation (transition from solid to gas) of volatile compounds. The early onset of sublimation indicates the presence of highly volatile ices, potentially providing a pristine record of the object’s origin outside the Solar System.

    Dr. Davenport emphasized that 3I/ATLAS is moving faster than either of the previous interstellar visitors at roughly 60 m/s, suggesting it was ejected from its parent stellar system with substantial kinetic energy, possibly due to gravitational interactions with massive planetary bodies or close stellar encounters.

    Multi-Wavelength Observations in Progress

    Optical Monitoring Through Citizen Science

    Dr. Graykowski leads optical monitoring efforts using the UNISTELLAR Network, a decentralized array of small, smart telescopes operated by citizen scientists worldwide. Despite the object’s faintness, UNISTELLAR telescopes (with apertures of just 3-4.5 inches) have successfully detected it using image stacking techniques to compensate for the comet’s rapid motion.

    Early brightness measurements reveal a steep increase in luminosity, which is consistent with dynamic new comets making their first close approach to a star. This rapid brightening reflects the sublimation of volatile compounds that have remained unaltered since their formation, offering a unique opportunity to probe primordial interstellar materials.

    Radio Observations at the Allen Telescope Array

    Radio observations began promptly at the SETI Institute’s Allen Telescope Array (ATA), led by Dr. Wael Farah. The ATA team initiated monitoring on the night of July 2, targeting both narrowband emissions (a potential indicator of artificial (technological) signals) and natural emissions such as continuum radiation from dust and specific spectral lines associated with common molecules like hydroxyl (OH).

    Within just a week, the ATA had amassed over 21 terabytes of data, equivalent to thousands of hours of high-resolution video. This dataset is under active analysis, with researchers scouring the data for both natural radio signatures and hypothetical technosignatures.

    Prospects for Spectroscopic Analysis

    Future observations from large facilities, including the Vera C. Rubin Observatory, will enable detailed spectroscopic studies, which are a technique used to decipher the chemical composition of astronomical objects. Spectroscopy will allow scientists to determine whether 3I/ATLAS harbors exotic compounds not commonly found in Solar System comets.

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  • NASA Invites Media to SpaceX’s 33rd Resupply Launch to Space Station

    NASA Invites Media to SpaceX’s 33rd Resupply Launch to Space Station

    Media accreditation is open for the next launch to deliver NASA science investigations, supplies, and equipment to the International Space Station. This launch is the 33rd SpaceX commercial resupply services mission to the orbital laboratory for NASA and will liftoff on the company’s Falcon 9 rocket.

    NASA and SpaceX are targeting no earlier than Thursday, Aug. 21, to launch the SpaceX Dragon spacecraft from Space Launch Complex-40 at Cape Canaveral Space Force Station in Florida.

    Credentialing to cover prelaunch and launch activities is open to U.S. media. The application deadline for U.S. citizens is 11:59 p.m. EDT, Sunday, Aug. 3. All accreditation requests must be submitted online at:

    https://media.ksc.nasa.gov

    Credentialed media will receive a confirmation email upon approval. NASA’s media accreditation policy is available online. For questions about accreditation, or to request special logistical support, email: ksc-media-accreditat@mail.nasa.gov. For other questions, please contact NASA’s Kennedy Space Center newsroom at: 321-867-2468.

    Para obtener información sobre cobertura en español en el Centro Espacial Kennedy o si desea solicitor entrevistas en español, comuníquese con Antonia Jaramillo o Messod Bendayan a: antonia.jaramillobotero@nasa.gov o messod.c.bendayan@nasa.gov.

    Each resupply mission to the station delivers scientific investigations in the areas of biology and biotechnology, Earth and space science, physical sciences, and technology development and demonstrations. Cargo resupply from U.S. companies ensures a national capability to deliver scientific research to the space station, significantly increasing NASA’s ability to conduct new investigations aboard humanity’s laboratory in space.

    In addition to food, supplies, and equipment for the crew, Dragon will deliver several new experiments, including bone-forming stem cells for studying bone loss prevention and materials to 3D print medical implants that could advance treatments for nerve damage on Earth. Dragon also delivers bioprinted liver tissue to study blood vessel development in microgravity and supplies to 3D print metal cubes in space.

    For almost 25 years, humans have continuously lived and worked aboard the International Space Station, advancing scientific knowledge and demonstrating new technologies that enable us to prepare for human exploration of the Moon as we prepare for Mars.

    Learn more about NASA’s commercial resupply missions at:

    https://www.nasa.gov/station

    -end-

    Claire O’Shea
    Headquarters, Washington
    202-358-1100
    claire.a.o’shea@nasa.gov

    Stephanie Plucinsky / Steven Siceloff / Danielle Sempsrott
    Kennedy Space Center, Fla.
    321-876-2468
    stephanie.n.plucinsky@nasa.gov / steven.p.siceloff@nasa.gov / danielle.c.sempsrott@nasa.gov

    Sandra Jones
    Johnson Space Center, Houston
    281-483-5111
    sandra.p.jones@nasa.gov

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  • Deep-sea fish confirmed as a significant source of ocean carbonate

    Deep-sea fish confirmed as a significant source of ocean carbonate

    image: 

    Martin Grosell, Ph.D., observes the blackbelly rosefish, the subject of the study. 


    view more 

    Credit: Diana Udel, University of Miami

    Deep-sea fish confirmed as a significant source of ocean carbonate

    New research sheds light on the overlooked contribution of the ocean’s most abundant fish to marine carbon cycling. The findings open new avenues for studying deep-sea carbon dynamics and may improve Earth system models.

    MIAMI, FL — July 25, 2025 – A new study offers the first direct evidence that deep-dwelling mesopelagic fish, which account for up to 94 percent of global fish biomass, excrete carbonate minerals at rates comparable to shallow-water species. The findings validate previous global models suggesting that marine fish are major contributors to biogenic carbonate production in the ocean.

    Scientists at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science studied the blackbelly rosefish (Helicolenus dactylopterus), a deep-sea species living at depths of 350-430 meters (1,148-1,410 feet), to determine whether it forms and excretes intestinal carbonate—known as ichthyocarbonate. This physiological process, common among marine fish, helps maintain internal salt and water balance in saline environments and plays a critical role in marine carbon cycling.

    “Mesopelagic fish live in deep, cold, high-pressure environments, and until now, it was unclear if they produced carbonate like shallow water fish do— or at what rate,” Martin Grosell, the lead author of the study and chair of the Department of Marine Biology and Ecology at the Rosenstiel School, said. “This study is the first to confirm that they do and that the mechanisms and characteristics of ichthyocarbonate formation are remarkably consistent across depths.”

    The blackbelly rosefish was an ideal model. Unlike many mesopelagic species, it lacks a swim bladder and can survive both capture and lab acclimation. Researchers maintained specimens at 6 degrees Celsius, replicating their natural habitat, and found they excreted approximately 5 milligrams of ichthyocarbonate per kilogram per hour, aligning with predictions from thermal and metabolic scaling models.

    “This research fills a major gap in our understanding of ocean chemistry and carbon cycling,” Amanda Oehlert, co-author and assistant professor in the Department of Marine Geosciences, said. “With mesopelagic fish playing such a significant role, their contribution to carbonate flux—and how it might change with warming oceans—deserves greater attention.”

    Key findings include:

    • Deep-sea blackbelly rosefish produce carbonate at rates and compositions comparable to shallower fish, confirming that depth and pressure do not inhibit ichthyocarbonate formation.
    • These results strengthen global estimates of fish-derived carbonate production, confirming that mesopelagic fish are substantial contributors to the ocean’s carbonate budget.
    • Ichthyocarbonate composition is similar regardless of the depth at which it forms, which influences how and where it is stored or dissolved in the ocean.

    “These results offer strong support for global models of fish-derived carbonate production, which had assumed—but not verified—that mesopelagic species contribute at similar rates,” Grosell said. “Mesopelagic fish aren’t just prey; they’re chemical engineers of the ocean.”

    The study underscores the importance of ichthyocarbonate in the ocean carbon cycle, especially given the vast, underexplored biomass of the mesopelagic zone.

    The authors say the findings open new avenues for studying deep-sea carbon dynamics and may improve Earth system models, which are sophisticated computer models that incorporate interactions between physical, chemical, and biological processes, such as biological carbon production and export.

    The study, titled “Osmoregulation by the gastro-intestinal tract of marine fish at depth—implications for the global carbon cycle,” was published on July 15, 2025 in the Journal of Experimental Biology. The authors are Martin Grosell, Bret Marek, Sarah Wells, Carolyn Pope, Cameron Sam, Rachael M. Heuer, and Amanda M. Oehlert, all from the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science.

    Funding for the study was provided by the National Science Foundation Chemical Oceanography Program and Earth Sciences Instrumentation and Facilities, and the University of Miami Rosenstiel School’s Departments of Marine Biology and Ecology and Marine Geosciences.


    Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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  • Multi-Wavelength Dust Characterization of the HL Tau Disk and Implications for Planet Formation

    Multi-Wavelength Dust Characterization of the HL Tau Disk and Implications for Planet Formation

    Images of dust continuum emission of the HL Tau disk. An arcsinh stretch is applied to the color scale. — astro-ph.EP

    We present a comprehensive analysis of the HL Tau dust disk by modeling its intensity profiles across six wavelengths (0.45 to 7.9 mm) with a resolution of 0.05 arcsec (∼7 au).

    Using a Markov Chain Monte Carlo (MCMC) approach, we constrain key dust properties including temperature, surface density, maximum grain size, composition, filling factor, and size distribution. The full fitting, with all parameters free, shows a preference for organics-rich dust with a low filling factor in the outer region (r≳40 au), where the spectral index is ∼3.7, but amorphous-carbon-rich dust also reasonably reproduces the observed intensity profiles.

    Considering the scattering polarization observed at 0.87 mm, compact, amorphous-carbon-rich dust is unlikely, and moderately porous dust is favored. Beyond 40 au, the maximum dust size is likely ∼100 μm if dust is compact or amorphous-carbon rich.

    However, if the dust is moderately porous and organics-rich, both the predicted dust surface density and dust size can be sufficiently large for the pebble accretion rate to reach ∼10M Myr−1 in most regions, suggesting that pebble accretion could be a key mechanism for forming planets in the disk.

    In contrast, if the dust is amorphous-carbon-rich, forming a giant planet core via pebble accretion is unlikely due to the combined effects of low dust surface density and small dust size required to match the observed emission, suggesting other mechanisms, such as disk fragmentation due to gravitational instability, may be responsible for planet formation in the HL Tau disk.

    Takahiro Ueda, Sean M. Andrews, Carlos Carrasco-González, Osmar M. Guerra-Alvarado, Satoshi Okuzumi, Ryo Tazaki, Akimasa Kataoka

    Comments: 20 pages, 11 figures, accepted for publication in ApJ
    Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
    Cite as: arXiv:2507.14443 [astro-ph.EP] (or arXiv:2507.14443v1 [astro-ph.EP] for this version)
    https://doi.org/10.48550/arXiv.2507.14443
    Focus to learn more
    Submission history
    From: Takahiro Ueda
    [v1] Sat, 19 Jul 2025 02:39:16 UTC (10,856 KB)
    https://arxiv.org/abs/2507.14443
    Astrobiology, Astrochemistry,

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