SPACE
Which came first: Black holes or galaxies?
Findings 'completely shake up' what we know about galaxy formation
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AN ILLUSTRATION OF A MAGNETIC FIELD GENERATED BY A SUPERMASSIVE BLACK HOLE IN THE EARLY UNIVERSE, SHOWING TURBULENT PLASMA OUTFLOWS THAT HELP TURN NEARBY GAS CLOUDS INTO STARS. NEW FINDINGS SUGGEST THIS PROCESS MIGHT BE RESPONSIBLE FOR ACCELERATED STAR FORMATION IN THE FIRST 50 MILLION YEARS OF THE UNIVERSE.
view moreCREDIT: ROBERTO MOLAR CANDANOSA/JOHNS HOPKINS UNIVERSITY
Black holes not only existed at the dawn of time, they birthed new stars and supercharged galaxy formation, a new analysis of James Webb Space Telescope data suggests.
The insights upend theories of how black holes shape the cosmos, challenging classical understanding that they formed after the first stars and galaxies emerged. Instead, black holes might have dramatically accelerated the birth of new stars during the first 50 million years of the universe, a fleeting period within its 13.8 billion—year history.
"We know these monster black holes exist at the center of galaxies near our Milky Way, but the big surprise now is that they were present at the beginning of the universe as well and were almost like building blocks or seeds for early galaxies," said lead author Joseph Silk, a professor of physics and astronomy at Johns Hopkins University and at Institut of Astrophysics, Paris, Sorbonne University. "They really boosted everything, like gigantic amplifiers of star formation, which is a whole turnaround of what we thought possible before—so much so that this could completely shake up our understanding of how galaxies form."
The work is newly published in the Astrophysical Journal Letters.
Distant galaxies from the very early universe, observed through the Webb telescope, appear much brighter than scientists predicted and reveal unusually high numbers of young stars and supermassive black holes, Silk said.
Conventional wisdom holds that black holes formed after the collapse of supermassive stars and that galaxies formed after the first stars lit up the dark early universe. But the analysis by Silk's team suggests that black holes and galaxies coexisted and influenced each other's fate during the first 100 million years. If the entire history of the universe were a 12-month calendar, those years would be like the first days of January, Silk said.
"We're arguing that black hole outflows crushed gas clouds, turning them into stars and greatly accelerating the rate of star formation," Silk said. "Otherwise, it's very hard to understand where these bright galaxies came from because they're typically smaller in the early universe. Why on earth should they be making stars so rapidly?"
Black holes are regions in space where gravity is so strong that nothing can escape their pull, not even light. Because of this force, they generate powerful magnetic fields that make violent storms, ejecting turbulent plasma and ultimately acting like enormous particle accelerators, Silk said. This process, he said, is likely why Webb's detectors have spotted more of these black holes and bright galaxies than scientists anticipated.
"We can't quite see these violent winds or jets far, far away, but we know they must be present because we see many black holes early on in the universe," Silk explained. "These enormous winds coming from the black holes crush nearby gas clouds and turn them into stars. That's the missing link that explains why these first galaxies are so much brighter than we expected."
Silk's team predicts the young universe had two phases. During the first phase, high-speed outflows from black holes accelerated star formation, and then, in a second phase, the outflows slowed down. A few hundred million years after the big bang, gas clouds collapsed because of supermassive black hole magnetic storms, and new stars were born at a rate far exceeding that observed billions of years later in normal galaxies, Silk said. The creation of stars slowed down because these powerful outflows transitioned into a state of energy conservation, he said, reducing the gas available to form stars in galaxies.
"We thought that in the beginning, galaxies formed when a giant gas cloud collapsed," Silk explained. "The big surprise is that there was a seed in the middle of that cloud—a big black hole—and that helped rapidly turn the inner part of that cloud into stars at a rate much greater than we ever expected. And so the first galaxies are incredibly bright."
The team expects future Webb telescope observations, with more precise counts of stars and supermassive black holes in the early universe, will help confirm their calculations. Silk expects these observations will also help scientists piece together more clues about the evolution of the universe.
"The big question is, what were our beginnings? The sun is one star in 100 billion in the Milky Way galaxy, and there's a massive black hole sitting in the middle, too. What's the connection between the two?" he said. "Within a year we'll have so much better data, and a lot of our questions will begin to get answers."
Authors include Colin Norman and Rosemary F. G. Wyse of Johns Hopkins; Mitchell C. Begelman of University of Colorado and National Institute of Standards and Technology; and Adi Nusser of the Israel Institute of Technology.
The team is supported by the Israel Science Foundation and the Asher Space Research Institute, as well as Eric and Wendy Schmidt by recommendation of the Schmidt Futures program.
JOURNAL
The Astrophysical Journal Letters
ARTICLE TITLE
Which Came First: Supermassive Black Holes or Galaxies? Insights from JWST
Mimas' surprise: Tiny moon holds young ocean beneath icy shell
Hidden beneath the heavily cratered surface of Mimas, one of Saturn's smallest moons, lies a secret: a global ocean of liquid water. This astonishing discovery, led by Dr. Valéry Lainey of the Observatoire de Paris-PSL and published in the journal Nature, reveals a "young" ocean formed just 5 to 15 million years ago, making Mimas a prime target for studying the origins of life in our Solar System.
“Mimas is a small moon, only about 400 kilometers in diameter, and its heavily cratered surface gave no hint of the hidden ocean beneath," says Dr Nick Cooper, a co-author of the study and Honorary Research Fellow in the Astronomy Unit of the School of Physical and Chemical Sciences at Queen Mary University of London. "This discovery adds Mimas to an exclusive club of moons with internal oceans, including Enceladus and Europa, but with a unique difference: its ocean is remarkably young, estimated to be only 5 to 15 million years old."
This young age, determined through detailed analysis of Mimas's tidal interactions with Saturn, suggests the ocean formed recently, based on the discovery of an unexpected irregularity in its orbit. As a result, Mimas provides a unique window into the early stages of ocean formation and the potential for life to emerge.
“The existence of a recently formed liquid water ocean makes Mimas a prime candidate for study, for researchers investigating the origin of life,” explains Dr Cooper. The discovery was made possible by analysing data from NASA's Cassini spacecraft, which meticulously studied Saturn and its moons for over a decade. By closely examining the subtle changes in Mimas's orbit, the researchers were able to infer the presence of a hidden ocean and estimate its size and depth.
Dr Cooper continues: “This has been a great team effort, with colleagues from five different institutions and three different countries coming together under the leadership of Dr Valéry Lainey to unlock another fascinating and unexpected feature of the Saturn system, using data from the Cassini mission.”
The discovery of Mimas's young ocean has significant implications for our understanding of the potential for life beyond Earth. It suggests that even small, seemingly inactive moons can harbor hidden oceans capable of supporting life-essential conditions. This opens up exciting new avenues for future exploration, potentially leading us closer to answering the age-old question: are we alone in the universe?
JOURNAL
Nature
ARTICLE TITLE
A recently-formed ocean inside Saturn’s moon Mimas
ARTICLE PUBLICATION DATE
7-Feb-2024
HKU astrophysicists crack the case of “disappearing” Sulphur in planetary nebulae
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A NOW ICONIC COLLAGE FROM OUR GROUP SHOWING 22 INDIVIDUAL WELL-KNOWN PNE, ARTISTICALLY ARRANGED IN A SPIRAL PATTERN BY ORDER OF APPROXIMATE PHYSICAL SIZE. THE LARGEST PNE HAVE A SURFACE BRIGHTNESS ABOUT A HUNDRED THOUSAND TIMES FAINTER THAN THE SMALLEST AND CAN REACH UP TO 3 PC ACROSS.
view moreCREDIT: ESA/HUBBLE AND NASA, ESO, NOAO/AURA/NSF
Two astrophysicists from the Laboratory for Space Research (LSR) at The University of Hong Kong (HKU) have finally solved a 20-year-old astrophysical puzzle concerning the lower-than-expected amounts of the element Sulphur found in Planetary Nebulae (PNe) in comparison to expectations and measurements of other elements and other types of astrophysical objects.
The expected levels of Sulphur have long appeared to be “missing in action”. However, they have now finally reported for duty after hiding in plain sight, as a result of leveraging highly accurate and reliable data. The team has recently reported their findings in Astrophysical Journal Letters.
Background
PNe are the short-lived glowing, ejected, gaseous shrouds of dying stars that have long fascinated and enthused professional and amateur astronomers alike with their colourful and varied shapes. PNe live for only a few tens of thousands of years compared to their host stars, which can take billions of years before they pass through the PN phase on the way to becoming “white dwarfs”. Consequently, PNe provide an almost instantaneous snapshot of stellar death throes. They are a vital, scientific window into late-stage stellar evolution as their rich emission line spectra enable detailed studies of their chemical compositions.
The Enigmatic Sulphur Anomaly
Past studies showed that PNe optical spectra appeared to have a varying deficit of the element Sulphur. This deficit was difficult to explain because Sulphur, known as an “α element”, should be produced in lockstep with other elements like oxygen, neon, argon and chlorine in more massive stars. As a result, its cosmic abundance should also be directly proportional.
Surprisingly, while strong correlations between Sulphur and Oxygen abundances have been observed in H II regions (Hydrogen ionised region) and blue compact galaxies (see figure 2), PNe originating from low- to intermediate-mass stars consistently exhibit lower Sulfur levels, giving rise to the so-called mysterious “sulfur anomaly” that has perplexed and annoyed astronomers for decades.
Our Work Solving the Mystery
Ms Shuyu TAN, a graduate of HKU MPhil in Physics and Research Assistant at HKU LSR, along with her supervisor Professor Quentin PARKER, the Director of LSR, utilised an unprecedented sample of exceptional high signal to noise (S/N) optical spectra for approximately 130 PNe located in the centre of our Galaxy. This exceptional dataset had minimal background noise, allowing for a clear and detailed examination of the spectral features, helping the team effectively tackle and solve the mystery.
These PNe were observed using the world-leading European Southern Observatory (ESO) 8m Very Large Telescope in Chile. It turns out the anomaly was essentially a result of poor data quality for Sulphur emission lines in PNe spectra. It was found that using Oxygen as the base metallicity comparator to other elements was not accurate, and instead, Argon demonstrated a stronger correlation with Oxygen for Sulphur and has been suggested as a more reliable indicator of metallicity and a suitable comparison element.
So, when a large, carefully selected sample of PNe are spectroscopically observed at high S/N on a large telescope, not only did the data reveal a strong “lock-step” behaviour or Sulphur in PNe for the first time, as seen and expected for other types of astrophysical objects, but the anomaly itself effectively went away.
The authors have effectively disproven previous claims suggesting that the sulfur anomaly in Planetary Nebulae was a result of underestimated higher sulfur ionization stages or weak sulfur line fluxes. This finding underscores the critical importance of high-quality data in unraveling scientific mysteries.
The Journal paper can be accessed here: https://iopscience.iop.org/article/10.3847/2041-8213/ad1ed9/pdf
Remark 1: The image idea originated from Quentin Parker and Ivan Bojičić, and it was rendered by Ivan Bojičić with input from David Frew and Shuyu Tan. The names of all these iconic PNe in the figure starting at the top left-hand corner and following the spiral are: Abell 33, K 1–22, NGC 7293, IC 5148/50, NGC 2818, NGC 6853, NGC 5189, IC 4406, Shapley 1, IC 289, Fleming 1, NGC 3132, IC 4406, NGC 6720, NGC 2440, NGC 1501, NGC 2392, NGC 6543, NGC 6826, NGC 7009, IC 418, NGC 7027, HD 44179.
Images download and captions: https://www.scifac.hku.hk/press
Figure 2. The vertical axis for both plots – sulphur abundance relative to Hydrogen.
Left plot – the sulphur anomaly (blue points are for PNe, green points for HII regions and blue compact galaxies) where Sulfur is shown relative to Oxygen. There is a large scatter for PN measure compared to the 1:1 lock-step behaviour expected and seen for other alpha elements in PNe.
Right plot: The green points are as before but this time the orange points are for the PNe from our VLT galactic centre PN sample and with sulphur plotted against Argon rather than Oxygen. There is now lock-step behaviour seen for sulphur for the first time and a parallel track and much tighter relationship where the anomaly is almost extinguished.
CREDIT
Figure adapted from The Astrophysical Journal Letters, 961:L47(9pp),2024 February 1.
Figure 3. Image from an ESO telescope in Chile of Planetary Nebulae PN NGC 5189. Some say it looks like a Chinese flying Dragon in space.
CREDIT
ESO
JOURNAL
The Astrophysical Journal Letters
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Whither or Wither the Sulfur Anomaly in Planetary Nebulae?
Will this new solar maximum solve the puzzle of the Sun’s gamma-ray picture?
FACULTY OF SCIENCES OF THE UNIVERSITY OF LISBON
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ARTIST’S CONCEPT OF NASA’S FERMI GAMMA-RAY SPACE TELESCOPE. FERMI SCANS THE ENTIRE SKY EVERY THREE HOURS AS IT ORBITS EARTH.
view moreCREDIT: NASA’S GODDARD SPACE FLIGHT CENTER/CHRIS SMITH (USRA/GESTAR)
The Sun’s polar regions were the most active emitting high energy radiation during the previous solar maximum, an imbalance yet to be explained, and reported for the first time in a study led by a researcher of the Faculty of Sciences of the University of Lisbon (Ciências ULisboa) (Portugal).
The Sun shines brightly in the visible light, but how does it look like at the highest energies of the electromagnetic radiation? The Sun’s picture taken in gamma rays is a deadly sight, luckily blinded by the Earth’s atmosphere and only seen from space. Each photon carries a billion times more energy than its ultraviolet sibling. How does the Sun’s regular gamma rays’ emission vary with time? And is it possible to link it to the periods of violent events we witness on the surface of our star?
A new study, published today in The Astrophysical Journal, produced a compressed fourteen years movie of the Sun observed in gamma rays, a visualization tool which revealed that, contrary to the expected uniform distribution of these high energy photons, the solar disk can become brighter on the polar regions. This tendency for the Sun’s glow in the gamma rays to be dominant at the highest latitudes is evident during the peak of the solar activity, as could be seen in June of 2014.
The study, led by Bruno Arsioli, of the Institute of Astrophysics and Space Sciences (IA), in Portugal, and the Faculty of Sciences of the University of Lisbon (Ciências ULisboa), may contribute to the understanding of the yet unknown process that makes the Sun shine ten times brighter in gamma rays than physicists expected. It might as well inform space weather forecasts.
Solar gamma rays are produced in our star’s halo and in solar flares, but also released from its surface. The latest were the focus of this study. “The Sun is stormed with close to light-speed particles coming from beyond our galaxy in all directions,” says Bruno Arsioli. “These so-called cosmic rays are electrically charged and are deflected by the Sun’s magnetic fields. Those that interact with the solar atmosphere produce a shower of gamma rays”.
Scientists thought these showers had equal chances of being seen anywhere across the Sun’s disk. What this work suggests is that cosmic rays might interact with the Sun’s magnetic field and thus produce a gamma-ray distribution that is not uniform across all latitudes of our star.
“We also detected a difference in energy between the poles,” Bruno Arsioli adds. “In the south pole there is a surplus of emissions of higher energy, of photons with 20 to 150 gigaelectronvolts, while most of the less energetic photons come from the north pole.” Scientists haven’t yet an explanation for this asymmetry.
During the maximum of the solar activity cycle, it is evident that gamma rays are being radiated more often at higher latitudes. They were particularly concentrated on the solar poles in June of 2014, upon the reversal of the solar magnetic field. This is when the Sun’s magnetic field dipole swaps its two signs, a peculiar phenomenon that is known to happen at the peak of solar activity, once every eleven years.
“We have found results that challenge our current understanding of the Sun and its environment,” says Elena Orlando, of University of Trieste, INFN, and Stanford University, and co-author of this study. “We demonstrated a strong correlation of the asymmetry in the solar gamma-ray emission in coincidence with the solar magnetic field flip, which has revealed a possible link among solar astronomy, particle physics, and plasma physics.”
The data used came from 14 years of observations with the gamma rays satellite Fermi Large Area Telescope (Fermi-LAT), between August 2008 and January 2022. This period covered a full solar cycle, from a minimum to the next, with the peak in 2014. One of the challenges was to disentangle solar emissions from the numerous other sources of gamma rays in the background sky, crossed by the apparent trajectory of the Sun. Bruno Arsioli and his colleague Elena Orlando produced a tool to integrate all the solar gamma-ray events within a window of the order of 400 to 700 days, and this window can slide across the 14-year period. Through this visualization (available in the media-kit below), the moments of polar excesses became clear, as well as the energy discrepancy between north and south.
“The study of gamma-ray emissions from the Sun represents a new window to investigate and understand the physical processes that happen in the atmosphere of our star,” says Arsioli. “What are the processes that create these excesses at the poles? Maybe there are additional mechanisms generating gamma rays that go beyond the interaction of cosmic rays with the surface of the Sun.”
Yet, if we stick to cosmic rays, they may work as a probe of the inner solar atmosphere. The analysis of these Fermi-LAT observations also motivates a new theoretical approach that should consider a more detailed description of the magnetic fields of the Sun.
The possible connection between the Sun’s production of gamma rays and its spectacular periods of more frequent solar flares and coronal mass ejections, and between these and the changes in the magnetic configuration of our star, may be an ingredient to improve the physical models that predict the solar activity. These are the basis of space weather forecasts, essential to protect instruments on satellites in space and telecommunications and other electronic infrastructures on Earth.
“In 2024 and the next year we will experience a new solar maximum, and another inversion of the Sun’s magnetic poles has already started. We expect by the end of 2025 to reassess if the inversion of the magnetic fields is followed by a surplus in the gamma rays emissions from the poles,” says Bruno Arsioli. Elena Orlando adds: “We have found the key to unlock this mystery, which suggests the future directions that should be taken. It is fundamental that the Fermi telescope will operate and observe the Sun in the coming years.”
But the solar gamma rays are likely to have more to reveal and demand further attention. This study now published will strengthen the science case for the continuous monitoring of the Sun by the next generation of gamma rays space observatories. “If it is settled that high energy emissions really carry information about the solar activity, then the next mission should be planned to provide real time data on gamma-ray emissions from the Sun,” says Arsioli.
Color-coded density plot of gamma rays emitted by the Sun between October 2013 and January 2015.
Color-coded density plot of gamma rays with energies between 5 and 150 gigaelectronvolts per photon, emitted by the Sun between October 2013 and January 2015, and registered by NASA’s Fermi-LAT telescope. It is superimposed on a false color image of the Sun in ultraviolet light, obtained with NASA’s Solar Dynamics Observatory in December 2014.
CREDIT
Arsioli and Orlando 2024 & NASA/SDO/Duberstein
JOURNAL
The Astrophysical Journal
ARTICLE TITLE
Yet Another Sunshine Mystery: Unexpected Asymmetry in GeV Emission from the Solar Disk
ARTICLE PUBLICATION DATE
7-Feb-2024
MXene-coated devices can guide microwaves in space and lighten the payload
Finding is a step toward lightweight replacements for metal components in space technology
Peer-Reviewed PublicationIMAGE:
RESEARCHERS FROM DREXEL UNIVERSITY AND THE UNIVERSITY OF BRITISH COLUMBIA HAVE DEMONSTRATED THAT POLYMERIC WAVEGUIDE COMPONENTS COATED IN MXENE INK CAN PERFORM AS WELL AS THEIR METAL COUNTERPARTS AND COULD PROVIDE A LIGHTWEIGHT ALTERNATIVE FOR FUTURE SPACE TECHNOLOGY.
view moreCREDIT: DREXEL UNIVERSITY/UNIVERSITY OF BRITISH COLUMBIA
One of the most important components of satellites that enable telecommunication is the waveguide, which is a metal tube for guiding radio waves. It is also one of the heaviest payloads satellites carry into orbit. As with all space technology, reducing weight means reducing the amount of expensive and greenhouse gas-producing fuel it takes to launch a rocket, or increasing the number of devices carried by the same rocket to space. Researchers from Drexel University and the University of British Columbia are trying to lighten the load by creating and testing a waveguide made from 3D-printed polymers coated with a conductive nanomaterial called MXene.
In their paper recently published in the journal Materials Today, the group reported on the potential of using MXene coatings to impart lightweight nonconductive components with electrical conductivity — a property sacrificed in additive manufacturing using polymer materials, such as plastics.
“In spaceflight applications, every extra gram of weight counts,” said Yury Gogotsi, PhD, Distinguished University and Bach Professor in Drexel’s College of Engineering, who is a leader in MXene research. “MXene materials provide one of the thinnest possible coatings — their flakes have a thickness of a few atoms — that can create a conductive surface, so we see great potential in using MXenes to treat additive manufactured components made of polymers that have complex shapes.”
Waveguides function as pipelines for microwaves. They direct the waves to receivers while preserving the power of the signal. In a microwave oven, waveguides ensure heating of the food; on a satellite, they transfer high-quality signals between different objects within and between satellites, as well as between satellites and Earth.
And, like the intricate network of pipes winding their way through a home, waveguides are designed in a range of shapes to fit into confined spaces. They can range from simple, straight channels to structures as complex as a labyrinth.
"Waveguides can be as basic as a straight, rectangular channel or they can morph into shapes resembling a 'crazy straw,' with bends and twists," said Mohammad Zarifi, an associate professor, who studies microwave communication at the University of British Columbia and led the team’s electrical engineering and design efforts. “The real game-changer, however, is the advent of additive manufacturing methods, which allow for more complex designs that can be difficult to produce with metals.”
While just about any hollow tube could be used as a primitive “waveguide,” the ones that transmit electromagnetic waves — in microwave ovens and telecommunications devices, for example — must be made from a conductive material to preserve the quality of transmission. These waveguides are typically made from metals like silver, brass and copper. In satellites, aluminum is the lighter-weight choice.
The researchers from Drexel, who first discovered MXenes in 2011 and have led their research and development ever since, suggested the 2D nanomaterials would be a good candidate as a coating for the plastic waveguide components based on their previous discoveries that MXenes can block and channel electromagnetic radiation.
“Our MXene coating emerged as a strong candidate for this application because it is highly conductive, functions as an electromagnetic shield and can be produced simply by dipping the waveguide in MXenes dispersed in water,” said Lingyi Bi, a PhD candidate in Gogotsi’s group. “Other metallic paints have been tested, but due to the chemicals used to stabilize their metallic ingredients, their conductivity suffers in comparison to MXenes.”
In addition, the researchers reported that the MXene coating bonded exceptionally well to the 3D-printed nylon waveguides due to compatibility between their chemical structures. The team dip-coated lightweight guides of varying shapes and sizes — straight, bent, twisted and resonator-shaped — to test MXene’s ability to thoroughly cover their interior.
The MXene-coated nylon waveguides weigh about eight times less than the standard aluminum ones currently being used, and the MXene coating added just a tenth of a gram to the overall weight of the components.
Most importantly, the MXene waveguides performed nearly as well as their aluminum counterparts, showing an 81% efficiency in guiding electromagnetic waves between two terminals after just one cycle of dip coating, just a 2.3% drop off from the performance of aluminum. The researchers demonstrated that they could improve this transmission metric by varying layers of coating or the size of MXene flakes — reaching a top transmission efficiency of 95%.
This performance held steady when the transmission was dialed up to the different frequency bands, such as those currently used in low-Earth orbit satellite communications and a sufficiently high input power for these transmissions. It also did not significantly degrade after three months, an indicator of the durability of the coating.
“The MXene-coated waveguides still need to go through extensive testing and be certified for space use before they can be used on satellites,” said Roman Rakhmanov, a doctoral candidate at Drexel who participated in the research. “But this finding could be an important step toward the next generation of space technology.”
Gogotsi’s team plans to continue its exploration of MXene coatings in applications that could benefit from an alternative to metal components.
“These promising results suggest that MXene-coated components could be a viable lightweight replacement for waveguides used in space,” Gogotsi said. “We believe that the coatings could also be optimized for transmissions of varying frequencies and applied to a variety of additive-manufactured or injection-molded polymer components, providing a lightweight and low-cost alternative to metals in a number of terrestrial applications as well.”
Coating 3D-printed polymer waveguides could provide a lightweight alternative to metal compontents in space technlogy, according to new research from Drexel University and the University of British Columbia.
CREDIT
Drexel University/University of British Columbia
JOURNAL
Materials Today
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
MXene guides microwaves through 3D polymeric structures
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