Tag Archives: observed

Astronomers May Have Detected Signs of the Largest Star Ever Observed

Posted on by
Reply

Artist’s Impression of Population III Stars in the Early Universe

Noir Lab/NSF/AURA/J. da Silva/Space Engine/M. Zamani

The James Webb Space Telescope (JWST) offers astronomers a unique opportunity to explore distant galaxies that exist far beyond the early Universe. Some of these galaxies exhibit chemical signatures that may suggest the presence of exotic supermassive stars, possibly weighing up to 10,000 times that of our Sun.

These enormous stars are puzzling, as our current understanding suggests that stars in the nearby universe generally have a maximum size limit. “Our models for galaxy evolution are predicated on the assumption that stars cannot exceed around 120 solar masses,” explains Devesh Nandal at the Harvard-Smithsonian Center for Astrophysics, Massachusetts. “While we had theorized about stars potentially larger than this, there were no observational data to validate it.”

That all changed recently. Nandal and his team analyzed JWST observations of a distant galaxy dubbed GS 3073, discovering its chemical signature contained an unexpectedly high concentration of nitrogen. Though elevated nitrogen levels have also been noted in several other remote galaxies,

For most galaxies, nitrogen concentrations aren’t high enough to cause ambiguity and can be attributed to certain classes of relatively ordinary stars or other cosmic phenomena. However, this isn’t the case for GS 3073, as Nandal asserts that the nitrogen levels are simply too elevated.

There exists a hypothetical category of protostar referred to as a Population III star, which models indicate can grow to considerable sizes. Simulations suggest that if these stars form, they would produce significantly more nitrogen than typical stars. Nandal and his co-researchers concluded that only a handful of Population III stars—ranging from 1,000 to 10,000 solar masses—could account for the excess nitrogen observed in GS 3073. “Our research provides the most compelling evidence yet for the existence of Population III supermassive stars in the early universe,” he declares.

However, some scholars challenge whether only supermassive Population III stars can account for this data, or if they do so accurately. “Population III should be linked with an environment where elements heavier than helium are scarce,” notes Roberto Maiorino of Cambridge University. “Conversely, GS 3073 is a fairly chemically mature galaxy, which makes it seem ill-suited for the types of environments typically associated with Population III.”

On the other hand, John Regan from Maynooth University in Ireland suggests that this may simply be an unusual galaxy. “When we look back at the early universe, what we see are incredibly strange, exotic galaxies. It’s challenging to assert that we shouldn’t expect the formation of supermassive stars simply because it’s peculiar; you just claimed these galaxies are quite bizarre,” he states.

If these colossal stars truly exist, they may unlock mysteries related to the formation of supermassive black holes in the universe’s distant past. Should they originate from supermassive stars instead of conventional stars, we could gain critical insights into how these black holes achieved their immense sizes in what appears to be a relatively brief time frame.

Confirming the existence of supermassive stars in GS 3073 and other nitrogen-rich galaxies from the early Universe is complex, and additional discoveries of these chemical signatures may be necessary. “It’s quite challenging to bolster the argument for their existence; establishing definitive signatures is difficult,” Regan lamented. “Nonetheless, this indication is incredibly robust.”

Topics:

Source: www.newscientist.com

The Galaxy Potentially Discovered by JWST Might Be the Earliest We’ve Ever Observed

Posted on by
Reply
SEI 264756217

A potentially newly discovered galaxy from the James Webb Space Telescope

NASA, ESA, CSA, CEERS, G. Gandolfi

Astronomers might have found galaxies that formed very early in the universe, approximately 200 million years apart from their closest counterparts, but they caution that alternative explanations could exist.

Giovanni Gandolfi from the University of Padua, along with his team, examined data from the James Webb Space Telescope (JWST) in search of distant cosmic formations from the universe’s 13.8 billion-year timeline.

The greater the distance of a galaxy from Earth, the longer it takes for its light to reach us, and it will be redshifted due to the universe’s expansion.

Until now, the earliest confirmed galaxy identified by JWST, named Mom-Z14, has a redshift of 14.4, indicating that it has been moving toward us since the universe was just 280 million years old. Gandolfi and his colleagues, however, have reported finding 32 intriguing objects with redshifts, placing them at a time when the universe was merely 90 million years old. They have named this discovery Capotauro after the Italian mountains.

“Capotauro could represent the most distant galaxy we’ve encountered,” states Gandolfi.

The team derived their conclusion from observing minor fluctuations in a deep JWST survey of the sky that resemble a distant galaxy. By utilizing various filters on the telescope, they were able to determine the redshift of the light emitted by the galaxy, arriving at a count of 32.

If validated, this object might represent a very young galaxy in formation, or potentially a primitive black hole enveloped by a dense atmosphere.

Nonetheless, this presumed galaxy appears uncommonly bright, akin to those observed in later redshift instances like Mom-Z14, suggesting it has a mass approximating a billion times that of the Sun.

For a galaxy to reach such mass, its efficiency in converting gas into stars must be near 100%, according to Nicha Reese Chawarit from the National Institute of Astronomy in Thailand, indicating that the stars cannot explode. Modelling, however, suggests that achieving 10-20% or even lower is plausible. “I believe there’s something amiss,” she remarks.

If this is not a galaxy, Gandolfi and his team propose that the object could alternatively be a brown dwarf (a star that didn’t ignite). These alternative theories are also compelling, Gandolfi notes, particularly if it is a cold brown dwarf or distant planet, possibly 6000 light years away and at room temperature.

“It could represent one of the first substellar objects ever formed in our galaxy,” adds Gandolfi.

To confirm this, the team requires additional observing time on the JWST to precisely analyze the light from the object. Leethochawalit supports the notion that it may not be a galaxy but also states that such follow-up research could still be worthwhile.

“If it turns out to be a galaxy with a redshift of 32, then a lot of our previous assumptions might be entirely wrong,” she states.

World Capital of Astronomy: Chile

Discover the astronomical wonders of Chile. Explore some of the world’s most advanced observatories and experience the starry skies under some of the clearest conditions on Earth.

Topic:

Source: www.newscientist.com

Astronomers Suggest 3i/Atlas Could Be the Most Ancient Comet Ever Observed

Posted on by
Reply

Research conducted by astronomer Matthew Hopkins and his team at Oxford University suggests that 3i/Atlas, the second interstellar comet discovered near our solar system, may have been on its trajectory over 3 billion years ago.

Top view of the Milky Way displaying the predicted orbits of our Sun and 3i/Atlas. Comets are represented by dashed red lines, while the sun is indicated by a dashed yellow line. The comet’s route to the outer thick disc is mostly clear, whereas the sun remains close to the nucleus of the galaxy. Image credit: M. Hopkins / Otautahi Oxford Team / ESA / Gaia / DPAC / Stefan Payne-Wardenaar / CC-SA 4.0.

“All comets formed alongside our solar system, like Halley’s comets, are up to 4.5 billion years old,” Dr. Hopkins explained.

“In contrast, interstellar visitors can be significantly older. Our statistical analyses indicate that 3i/Atlas is very likely to be the oldest comet we’ve observed thus far.”

Unlike 1i/Oumuamua and 2i/Borisov, the two previous interstellar objects that passed through our solar system, 3i/Atlas appears to be on a more inclined path through the Milky Way.

A recent study forecasts that 3i/Atlas is likely to be rich in water ice, as it probably formed around the star of the ancient, thick disc.

“This is an aspect of the galaxy that we’ve never encountered before,” said Chris Lintot, a professor at Oxford University and host of The Sky at Night.

“I believe there is a two-thirds chance that this comet predates the solar system and has been drifting through interstellar space ever since.”

As it nears the Sun, the heat from sunlight activates 3i/Atlas, generating a coma and tail composed of steam and dust.

Initial observations indicate that the comet is already active and may even be larger than any of its interstellar predecessors.

If this is validated, it could influence the detection of similar objects by future telescopes, such as the upcoming Vera C. Rubin Observatory.

Furthermore, it could offer insights into the role that ancient interstellar comets play in the formation of stars and planets throughout the galaxy.

“We’re in an exciting phase. 3i/Atlas is already displaying signs of activity,” remarked Dr. Michele Bannister, an astronomer at the University of Canterbury.

“The gases we might observe in the future, as 3i/Atlas is heated by the Sun, will help us evaluate our models.”

“Some of the world’s largest telescopes are currently monitoring this new interstellar entity. One of them may make a significant discovery!”

The astronomers presented their findings today at the National Astronomical Conference of the Royal Astronomical Society 2025 in Durham, England.

____

Matthew Hopkins et al. Intergalactic interstellar object population in LSST. NAM 2025

Source: www.sci.news

AI is Joining the Radiology Workforce: Efficiency Gains Observed So Far.

Posted on by
Reply

Nine years ago, a prominent artificial intelligence scientist picked an at-risk profession.

“Individuals should stop pursuing a career as a radiologist now,” stated Jeffrey Hinton, asserting that AI would undoubtedly surpass human performance in this area within five years.

Currently, radiologists—medical imaging specialists diagnosing and treating diseases—are still in significant demand. Recent studies indicate a steady workforce growth projected by the American College of Radiation until 2055.

Dr. Hinton, who earned a Nobel Prize in physics for his groundbreaking AI research last year, has indeed had a monumental influence on technology.

This is evident at Mayo Clinic, one of the nation’s premier healthcare systems, with its primary campus located in Rochester, Minnesota. In recent years, Mayo Clinic has embraced AI technology to analyze images, automate everyday tasks, detect medical issues, and forecast diseases. AI also acts as a “second opinion.”

“But will it replace radiologists? We don’t believe so,” said Dr. Matthew Colestrom, chairman of radiology at Mayo Clinic. “We understand how challenging this work is and its interrelations.”

Computer scientists, industry experts, and policymakers have long debated the future of AI in the workforce. Will it serve as a smart assistant, enhance human performance, or be a robotic agent that displaces millions of workers?

The conversation intensifies as the cutting-edge technology behind chatbots appears to be advancing more quickly than anticipated. Leaders from companies like OpenAI and others forecast that AI will automate most cognitive tasks within a few years. Conversely, numerous researchers predict a more gradual transformation, akin to the introduction of electricity and the Internet, consistent with historical technological disruptions.

The potential obsolescence of radiologists serves as an illustrative example. Thus far, AI has proven to be a robust medical asset that enhances efficiency and augments human abilities, rather than replacing them.

Radiology has been a primary focus in the development and implementation of AI in healthcare. Of the more than 1,000 AI applications approved by the Food and Drug Administration for medical purposes, approximately 75% pertain to radiology. AI excels in identifying and assessing specific abnormalities, such as lung lesions and breast tumors.

“While there have been remarkable advancements, these AI tools mainly focus on general cases,” remarked Dr. Charles E. Kern Jr., a radiology professor at the University of Pennsylvania’s Perelman School of Medicine and editor of the journal. Radiology: Artificial Intelligence.

Radiologists do much more than merely examine images. They provide consultations to other physicians and surgeons, engage with patients, compile reports, and scrutinize medical histories. After detecting potential tissue anomalies, they interpret the implications for individual patients based on their unique medical backgrounds, drawing from years of expertise.

David Ortl, a labor economist at the Massachusetts Institute of Technology, stated that AI “underestimates the intricacy of work performed by humans.”

At Mayo Clinic, AI tools are being researched, developed, and customized to align with the hectic schedules of physicians. Since Dr. Hinton’s prediction, the radiology staff has expanded by 55%, now exceeding 400 radiologists.

Prompted by concerns and advancements in AI-related image recognition in 2016, radiology leaders assembled a team to evaluate the potential effects of the technology.

“Our initial thought was to leverage this technology for our betterment,” recalled Dr. Callstrom. “That was our primary objective.”

A decision was made to invest. Today, the Department of Radiology boasts a 40-member AI team, featuring AI scientists, radiation researchers, data analysts, and software engineers. They have created a diverse suite of AI tools, from tissue analysis instruments to disease prediction models.

The team collaborates with specialists like Dr. Theodora Pototzke, who focuses on the kidneys, bladder, and reproductive organs. She regards the radiologist’s role as that of a “secondary physician,” clearly conveying imaging findings and providing guidance.

Dr. Pototzke employs AI tools to gauge kidney volume. Growth in the kidneys, when coupled with cysts, can signal a decline in function even before changes are detectable in blood tests. Previously, she measured kidney volume mainly by hand, akin to using an on-screen ruler, resulting in variable outcomes and lengthy processes.

Serving as a consultant, end user, and tester for the department’s AI team, Dr. Pototzke assisted in designing software with color coding for various conditions and evaluating measurements.

Now, she can simply retrieve an image on a computer, click an icon, and instantly see the kidney volume measurements. This saves her 15-30 minutes with each kidney scan and consistently yields accurate results.

“This is a fantastic example of effectively utilizing AI for increased efficiency and accuracy,” Dr. Pototzke commented. “AI can augment, enhance, and quantify processes, but I am not in a position to relinquish interpretative duties regarding technology.”

In the hall, staff radiologist Dr. Francis Buffer elaborated on the various AI applications prevalent in the field, often operating behind the scenes. He stated that manufacturers of MRI and CT scanners incorporate AI algorithms to expedite image acquisition and enhance quality.

AI also autonomously identifies images with the highest likelihood of abnormal findings, effectively informing the radiologist, “focus here first.” Another application scans for heart or lung clots, even when the medical emphasis lies elsewhere.

“AI is currently integrated throughout our workflow,” noted Dr. Buffer.

In total, Mayo Clinic implements over 250 AI models, both developed in-house and sourced from vendors. The Radiology and Heart Disease divisions are the largest consumers of these technologies.

In some circumstances, emergent technologies unveil insights surpassing human capabilities. One AI model analyzes ECG data to forecast patients likely to develop cardiac fibrillation.

Research initiatives in radiology utilize AI algorithms to detect subtle transformations in pancreatic shape and texture, potentially identifying cancers up to two years before conventional diagnoses. The Mayo Clinic team is collaborating with other healthcare organizations to further validate these algorithms with more data.

“Mathematical modeling enables us to perceive what the human eye cannot,” mentioned Dr. John Haramka, president of the Mayo Clinic Platform, overseeing the digital initiatives of the health system.

Dr. Halamka, an advocate for AI, is confident that this technology will revolutionize medicine.

“In five years, failing to use AI will be considered a form of medical malpractice,” he suggested. “However, this means that humans and AI will collaborate closely.”

Dr. Hinton concurs. Reflecting on his previous statements, he believes he was overly broad in 2016, clarifying that his remarks were solely about image analysis, and while he may have misjudged the timeline, he maintains his original stance.

Over the years, most medical imaging interpretations are made through a partnership between AI and radiologists, which not only enhances accuracy but also significantly increases radiologists’ efficiency, according to Dr. Hinton.

Source: www.nytimes.com

Scientists First Observed Volcanic Eruptions at Deep-Sea Ridges

Posted on by
Reply

Andrew Wozniak, a chemical oceanographer at the University of Delaware, found it difficult to comprehend the scene before him. Dr. Wozniak was stationed at the bottom of the Pacific Ocean, nearly 1.6 miles below the surface, aboard Alvin, the research submersible. As far as his eyes could scan, there lay a nearly desolate expanse of jet-black rock.

Just a day prior, this area was alive with the bustling activity around the Tika hydrothermal vent, situated about 1,300 miles west of Costa Rica. The rocky seabed was home to a vibrant ecosystem, teeming with life. Bright crimson-tipped giant tubeworms intertwined with clusters of mussels, encapsulated in a tapestry of thriving organisms. Crustaceans scuttled about, while ethereal white fish glided gracefully in search of their next meal.

Now, however, only a solitary cluster of dead tubeworms remained amid the darkened landscape. The vivid orange glow of molten lava flickered through the rocks, and a fine mist clouded the water.

“My mind was racing to grasp what had transpired,” Dr. Wozniak said. “Where did everything go?”

Then it dawned on him: he and his fellow explorers had observed the aftermath of a volcanic eruption that had obliterated a once-thriving ecosystem beneath a fresh layer of lava.

This marked the first time scientists had directly witnessed a clear eruption along a ridge in the Central Ocean, a volcanic mountain chain stretching approximately 40,000 miles globally. Baseball seams signify the boundaries of tectonic plates that, when separated, can trigger volcanic eruptions, creating new crust and layers of Earth’s structure beneath the ocean. Approximately 80% of Earth’s volcanic activity occurs at the seafloor, predominantly along the mid-ocean ridge. Before this recent observation, only two underwater eruptions had been documented, neither occurring along the mid-ocean ridge, noted Bill Chadwick, a volcanologist from Oregon State University who was not part of the research team.

“This is an incredibly exciting first,” he remarked.

Such observations provide an invaluable opportunity for scientists to explore fundamental processes of our planet: the formation of new seabeds and their dynamic influence on marine chemistry, ecosystems, microbial life, and beyond.

“Experiencing it in real time is an extraordinary gift. I’m truly envious,” said Deborah Kelly, a marine geologist at the University of Washington who did not participate in the research.

Dr. Wozniak and his team set sail on the R/V Atlantis before diving into the Alvin submersible. Their initial mission was to examine the carbon emissions from Tika’s vents, funded by the National Science Foundation. Hydrothermal vents act as planetary piping systems, discharging heated seawater from the seabed and facilitating the transport of heat and chemicals from within the Earth, thus regulating marine chemistry and sustaining a unique community of deep-sea organisms.

Tuesday morning’s dive commenced like any other. Alyssa Wentzel, an undergraduate from the University of Delaware, accompanied Dr. Wozniak in Alvin, sharing her excitement about descending into the ocean’s depths for a 70-minute journey to the seabed. As the lights dimmed, bioluminescent jellyfish and tiny zooplankton danced in the water.

“It felt magical,” she remarked. “It truly leaves you speechless.”

However, as they neared the site, the temperature gradually increased, shrouding the area in a dark haze. The seabed’s usual dull gray and brown tones were replaced with tendrils of glassy rock, an outcome of rapid cooling when lava makes contact with cold water.

As the particles clouded Alvin’s view, Caitlyn Biadshire, a pilot from Woods Hole Oceanographic Institution, guided the submersible while monitoring the temperature closely, concerned about the safety of the submersible and its crew. Ultimately, the pilot decided a retreat was necessary.

“It was a breathtaking sight,” they reflected. “Everything I observed just days earlier has been wiped away. I feel incredibly fortunate to have been there within hours of the eruption.”

After returning to the ship, the team learned that a sensitive microphone, known as a Hydrophone, was onboard the Atlantis and had recorded a series of low-frequency rumbles and crackling sounds reminiscent of a campfire.

This represented the third known eruption at the Tika Vent since its discovery in the 1980s. For decades, marine geologist Dan Fornari and his colleagues have closely monitored the site, tracking changes in temperature, water chemistry, and other factors. By combining these analyses with models of seafloor diffusion, they predicted an eruption was imminent, forecasting it could happen either earlier this year or in the previous year.

In 1991, they reached Tika shortly after an eruption began. Although it may have still been active, they lacked visual confirmation of the lava. This time, he asserted, there was no doubt about what the Alvin crew witnessed. “This was the closest we’ve ever come to witnessing the onset of an eruption,” he stated.

The team continues its research into volcanic activity. Due to safety considerations, they are now collecting data and capturing images from the Atlantis remotely.

This data aids researchers in unraveling the mysteries of deep-sea volcanism and its significance within marine ecosystems. “It’s all connected to understanding the overall system of Earth and the ocean,” Dr. Fornari stated. “The relationship is both intricate and beautiful.”

Source: www.nytimes.com

Strange vertical orbits of an exoplanet observed around a binary brown dwarf system

Posted on by
Reply

Impression of the artist in the unusual orbit around the brown dwarf of ExoPlanet 2M1510 (AB)B

ESO/L. Calsada

It was first revealed that a pair of rare stars have equally rare companions, exoplanets that rush into orbit vertically.

Astronomers may think they know what the normal thing is about stars and planets, but they say, “But the universe is very diverse.” Amaury Triaud At the University of Birmingham, UK. He and his colleagues unexpectedly discovered evidence of rare constructs while analyzing data collected by a very large Chilean telescope.

The two stars are brown d stars. This means that they are small and very dim because they cannot maintain fusion and are often referred to as failed stars or subseber ral objects. They follow orbit and continue to cover each other when viewed from Earth. Researchers have previously observed only one brown d-star binary.

Triaud and his colleagues carefully analyzed the new binary system to determine the mass of the stars and their movements, and unexpectedly strange signals were found in the data. Ultimately, the only physical scenario that can explain it is that of a planet-sized object orbiting two stars, following an ellipse perpendicular to the star’s orbit.

Triaud says that vertical orbit is not entirely unheard of, but he and his colleagues never expected to see it in this context. “Brown dwarfs are rare. Brown dwarf pairs are rare. Covering a pair of brown dwarfs is even more unusual and faint, making it difficult to measure,” he says. “That was a surprise. In a system that is ideal and not rare in itself, there is this configuration.”

Twenty years ago, such a structure was considered science fiction, but now it has become a scientific fact. Katherine Brandel At Oxford University. “This is a truly beautiful outcome,” she says. Details of the impending orbit of the two stars make a strong claim that this “harmonograph of the sky” is authentic. By studying how they eat each other, we can identify more details about this unique trio’s moves going forward, Blundell says.

Researchers would like to learn more about the exoplanet named 2M1510(AB)B, but can be compared to a fictional tattoo. Star Warsa desert world orbiting two suns. However, the two suns on the 2M1510(AB)B dimming and get exposed to the surface with something similar to the double dose of moonlight.

topic:

Source: www.newscientist.com

Astronomers find farthest rotating disk galaxy ever observed: REBELS-25

Posted on by
Reply

According to one researcher, REBELS-25 existed until 700 million years after the Big Bang. paper Published in Royal Astronomical Society Monthly Notices.

This image shows the galaxy REBELS-25, observed by ALMA, superimposed on infrared images of other stars and galaxies. This infrared image was taken by ESO's Visible Infrared Survey Telescope for Astronomy (VISTA). Image credits: ALMA / ESO / National Astronomical Observatory of Japan / NRAO / Roland others. / Dunlop others. / Cas / Kare.

The galaxies we see today are very different from the chaotic, clumpy galaxies that astronomers typically observed in the early universe.

These messy early galaxies merge with each other and evolve into smoother shapes at an incredibly slow pace.

Current theory suggests that it would take billions of years of evolution for galaxies to become as ordered as our Milky Way, a rotating disk with an orderly structure like spiral arms.

However, the detection of REBELS-25 casts doubt on that timescale.

“Our understanding of galaxy formation predicts that most early galaxies appear small and messy,” said Dr Jacqueline Hodge, an astronomer at Leiden University.

In their study, Dr. Hodge and colleagues found that REBELS-25 existed at redshift z = 7.3 (when the universe was only 700 million years old), making it the most distant object ever discovered. They discovered that it was a strongly rotating disk galaxy.

“Seeing galaxies so similar to our own Milky Way and with strong rotational dominance adds to our understanding of how galaxies in the early universe evolved into the ordered galaxies of today's universe. It raises questions,” says Lucy Roland, a PhD student at Leiden University. University.

REBELS-25 was detected by the authors using the Atacama Large Millimeter/Submillimeter Array (ALMA).

To precisely identify the galaxy's structure and motion, they conducted follow-up observations at higher resolution with ALMA, confirming its record-breaking nature.

Surprisingly, the data suggested more developed features similar to the Milky Way, such as an elongated central bar and spiral arms, but more observations are needed to confirm this. Probably.

“Finding further evidence of a more evolved structure would be an interesting discovery, as this would be the most distant galaxy in which such a structure has been observed to date,” Rowland said.

“These future observations from REBELS-25, along with other discoveries of early rotating galaxies, could change our understanding of early galaxy formation and the evolution of the universe as a whole.”

_____

Lucy E. Rowland others. REBELS-25: Dynamically cold disk galaxy discovered at z = 7.31. MNRASpublished online October 7, 2024. doi: 10.1093/mnras/stae2217

Source: www.sci.news

Unexpected forms of gamma-ray emissions observed in tropical thunderstorms

Posted on by
Reply

Thunderclouds include more than just rain and lightning. In addition to visible light radiation, thunderclouds can produce powerful bursts of gamma rays that last one millionth of a second. Clouds can also glow steadily with gamma rays for seconds to minutes at a time. Using a battery of detectors onboard NASA’s ER-2 research aircraft, scientists have discovered a new type of gamma-ray radiation whose duration is shorter than steady light but longer than microsecond bursts. They call it a flickering gamma ray flash.

NASA’s high-flying ER-2 plane is equipped with the Fly’s Eye Stationary Lightning Mapper Simulator, which records gamma rays (purple in the illustration) from thunderclouds, and instruments in this artist’s impression of the Airborne Lightning Observatory for the Ground Gamma Ray Flash (ALOFT) mission. is installed. Image credit: NASA/ALOFT team.

Previous studies have reported two types of gamma-ray emissions from thunderclouds. One is a high-intensity burst known as a terrestrial gamma-ray flash, and the other is a moderate-intensity, long-duration gamma-ray glow.

However, the characteristics of these emissions and how they are produced are not completely understood.

Researchers used data collected by the aircraft during 10 flights in July 2023 to investigate gamma-ray emissions that occurred during marine and coastal thunderstorms in the Caribbean and Central America.

“The ER-2 aircraft will be the ultimate platform for observing gamma rays from thunderclouds,” said Professor Nikolai Ostgaard of the University of Bergen.

“Flying at 20 km (12.4 miles) allows us to fly directly above the clouds, as close as possible to the gamma-ray source.”

“There’s a lot more going on in thunderstorms than we imagined,” added Professor Steve Comer of Duke University.

“At the end of the day, basically all large thunderstorms produce gamma rays in different forms throughout the day.”

“Several aircraft operations have attempted to determine whether these phenomena are common, but results have been mixed, and some operations over the United States have not found gamma rays at all.”

“This project was designed to answer these questions once and for all.”

Professor Ostgaard, Professor Comer and their colleagues. identified Another type of gamma-ray radiation, called flicker gamma-ray flashes, consists of pulses of longer duration than terrestrial gamma-ray flashes.

A total of 24 flickering gamma-ray flashes were observed as the spacecraft passed over gamma-ray thunderclouds on five of its 10 flights. Seventeen of these flickering gamma-ray flashes resulted in lightning.

The researchers suggested that flickering gamma-ray flashes, which can begin as the emission of gamma rays and then suddenly increase in intensity into a series of pulses, may also be involved in the formation of lightning. are.

Because flickering gamma-ray flashes share similar characteristics with gamma-ray glows and terrestrial gamma-ray flashes, they propose that flickering gamma-ray flashes could provide evidence of a link between the two phenomena.

In another study, Dr. Martino Marisardi from the University of Bergen and colleagues investigated Characteristics of gamma ray glow detected by aircraft.

These included thundercloud systems covering an area of ​​more than 9,000 km.2 Luminescence was observed for at least 3 hours.

They found that the emission was general and not uniform across the emission region.

During nine of the 10 flights, more than 500 individual gamma-ray glows were observed across the study area, each lasting between 1 and 10 seconds.

These findings contradict the results of previous studies that reported that the gamma-ray glow can last up to several hundred seconds and is emitted uniformly over a range of up to 20 km.

Taken together, these findings improve our understanding of gamma-ray emissions from thunderclouds and suggest a causal relationship between glows and flashes and the possible role of these emissions in the subsequent development of lightning.

“These two new forms of gamma rays are what I find most interesting,” Professor Comer said.

“They don’t seem to be related to the occurrence of lightning. They somehow appear naturally.”

“There are hints in the data that they may actually be related to the process that causes lightning, but it’s still a mystery to scientists.”

The results are published in two papers: journal nature.

_____

N. Ostgard others. 2024. Gamma ray flashing, the missing link between gamma rays and TGF. nature 634, 53-56; doi: 10.1038/s41586-024-07893-0

M. Marisardi others. 2024. Highly dynamic gamma-ray emissions are common in tropical thunderclouds. nature 634, 57-60; doi: 10.1038/s41586-024-07936-6

Source: www.sci.news

UGC 3478 observed by the Hubble Space Telescope

Posted on by
Reply

Stunning new images taken by the NASA/ESA Hubble Space Telescope show spiral galaxy UGC 3478 in great detail.

This Hubble Space Telescope image shows UGC 3478, a spiral galaxy located 128 million light-years away in the constellation Camelopardalis. Image credit: NASA / ESA / Hubble / M. Koss / A. Barth.

3478 posts It is located in the constellation Camelopardalis and is approximately 128 million light years away from Earth.

Also known as LEDA 19228, INTREF 304, IRAS 06280+6342, Seyfert galaxyA type of galaxy centered around an active galactic nucleus (AGN).

“If you look at the long, star-filled spiral arms and the dark threads of dust that crisscross them, your eye may be drawn to a bright spot at the center of UGC 3478,” the Hubble astronomers said.

“This spot is the core of a galaxy, and there's something very special about it: it's a growing massive black hole, what astronomers call an AGN.”

“As with other active galaxies, the brightness seen here hides a supermassive black hole at the galaxy's centre,” the researchers added.

“A disk of gas spirals into this black hole, and as the material collides and heats up, it emits extremely intense radiation.”

“The spectrum of this radiation includes hard X-ray emission, which makes it clearly distinguishable from stars in the galaxy.”

“Despite the strong brightness of the compact central region, the surrounding galactic disk is still clearly visible, making it a Seyfert galaxy.”

“Astronomers know that many active galaxies are far away from Earth because their nuclei are so bright that they stand out next to other fainter galaxies.”

“Located 128 million light-years away, UGC 3478 is Earth's very own neighbour,” the astronomers said.

The new image of UGC 3478 is Hubble's Advanced Camera for Surveys (ACS) is in the near infrared and optical parts of the spectrum.

Two filters were used to sample different wavelengths, and color was generated by assigning a different hue to each monochromatic image associated with an individual filter.

“The data used to create this image come from Hubble Space Telescope surveys of nearby powerful AGNs discovered in such relatively high-energy X-rays and are expected to help us understand how galaxies interact with their central supermassive black holes,” the researchers said.

Source: www.sci.news

NGC 2005 observed by Hubble Space Telescope

Posted on by
Reply

Astronomers using the NASA/ESA Hubble Space Telescope NGC 2005A globular cluster located in the constellation Dorado, 162,000 light years from Earth.

This Hubble image shows the globular cluster NGC 2005. The color composite was created from images taken in visible and near-infrared light by Hubble's Wide Field Camera 3 (WFC3). It is based on data acquired through three filters. The colors are produced by assigning a different hue to each monochromatic image associated with an individual filter. Image credit: NASA / ESA / Hubble / F. Niederhofer / L. Girardi.

Globular clusters are dense systems of very old stars bound by gravity into a single structure about 100-200 light years in diameter.

Star clusters contain hundreds of thousands, or even millions, of stars. A large mass at the center of the cluster pulls the stars inward, forming a sphere of stars. sphericalThese clusters are named after the Latin word ” ,” which means “little sphere.”

Globular clusters are among the oldest known objects in the universe, relics of early galaxy formation.

Of the Milky Way's 150 globular clusters, about 70 are located within 13,000 light-years of the galactic center, where their density tends to peak.

“Studying globular clusters in space is a bit like studying fossils on Earth: just as fossils give us insight into the characteristics of ancient plants and animals, globular clusters reveal the signature of ancient stars,” the Hubble astronomers said.

“Current theories of galactic evolution predict that galaxies will merge with each other.”

“The relatively large galaxies observed in the modern universe are widely thought to have formed by the merger of smaller galaxies.”

“If this is correct, astronomers will see evidence that the oldest stars in nearby galaxies originated in different galactic environments.”

“Globular clusters are known to contain ancient stars, and their stability makes them excellent laboratories to test this hypothesis.”

“NGC 2005 is just such a globular cluster, and its very existence provides evidence in support of the theory of galactic evolution by mergers.”

NGC 2005 is located about 750 light-years from the center of the Large Magellanic Cloud, the Milky Way's largest satellite galaxy.

Also known as ESO 56-138, this globular cluster is discovered It was discovered on September 24, 1826 by Scottish astronomer James Dunlop.

“The stars in NGC 2005 have a different chemical composition than the stars in the surrounding Large Magellanic Cloud,” the researchers said.

“This suggests that the Large Magellanic Cloud merged with another galaxy at some point in its history.”

“While other galaxies have long ago merged or dispersed, NGC 2005 remains as an ancient witness to a long-ago merger.”

Source: www.sci.news

Brightest Quasar Ever Observed Discovered by Astronomers

Posted on by
Reply

The black hole in the newly discovered quasar SMSS J052915.80-435152.0 (J0529-4351) accretes about 1 solar mass per day on top of its existing mass of 17 billion solar masses.

This image of the exceptional quasar J0529-4351 is from the Dark Energy Camera Legacy Survey DR10. Adjacent M stars are displayed in red.Image credit: Wolf other., doi: 10.1038/s41550-024-02195-x.

In 1963, Dutch-born American astronomer Maarten Schmidt identified the first quasar, known as 3C 273. It appeared as a very bright star of magnitude 12, and its redshift suggested that it was one of the most distant objects known in the universe. time.

These two facts suggest an incredibly huge light output, and ever since, newly discovered quasars have impressed with their ability to emit enormous amounts of energy from small regions of the universe. Ta.

This can only be explained by the conversion of gravitational energy into heat and light in a highly viscous accretion disk around a supermassive black hole.

Currently, about 1 million quasars are known, but a few specimens stand out. In 2015, ultraluminous quasar J0100+2802 was confirmed to be a supermassive black hole with 10 billion solar masses.

In 2018, an even brighter object, J2157-3602, was discovered, which contains a supermassive black hole with a mass of 24 billion solar masses.

Its brightness suggests rapid growth, but its existence is difficult to explain. When black holes start from the debris of a star's collapse and grow temporarily, they are not expected to reach appreciable mass in the time between the Big Bang and the black hole era. observation.

The quasar that broke the new record is so far from Earth that it took more than 12 billion years for its light to reach us.

The object, called J0529-4351, was first detected using the 2.3 meter telescope at the ANU Siding Spring Observatory.

Australian National University astronomer Christian Wolff and colleagues then turned to ESO's Very Large Telescope, one of the world's largest telescopes, to confirm the full nature of the black hole and measure its mass. Toward.

“We have discovered the fastest growing black hole ever known. It has a mass of 17 billion suns and eats just over one sun a day. This makes it the fastest growing black hole in the known universe. It will be a bright object,” Dr. Wolf said.

The material drawn into this black hole in the form of a disk emits so much energy that J0529-4351 is more than 500 trillion times brighter than the Sun.

“All this light comes from a hot accretion disk seven light-years in diameter, which must be the largest accretion disk in the universe,” said Dr. Student Samuel Lai.

“Given what we know about many other less impressive black holes, it's surprising that it hasn't been detected before. It was hiding in plain sight,” says the Australian National said Dr. Christopher Onken of the university.

This finding is reported in the following article: paper in diary natural astronomy.

_____

C.Wolf other. Accretion of solar masses per day by a 17 billion solar mass black hole. Nat Astron, published online on February 19, 2024. doi: 10.1038/s41550-024-02195-x

Source: www.sci.news

Potentially the heaviest neutron star ever observed found in mysterious object

Posted on by
Reply

A neutron star is the collapsed core of a massive star

www.science.org/doi/10.1126/science.adg3005

Some 40,000 light-years away, a strange object could be either the heaviest neutron star or the lightest black hole ever seen, and it resides in a mysterious celestial void that astronomers have never directly observed. .

Neutron stars form when a star runs out of fuel and collapses due to gravity, creating a shock wave called a supernova and leaving behind an extremely dense core. Astrophysical calculations show that these nuclei must remain below a certain mass, about 2.2 times the mass of the Sun, or they will collapse further to form a black hole.

However, black holes have only been observed to have a mass more than five times that of the sun, leaving a gap in scale between neutron stars and black holes. Gravitational-wave observatories have observed several dense objects in this gap, but astronomers have never discovered them with conventional telescopes.

now, Ewan Barr Researchers at Germany's Max Planck Institute for Radio Astronomy discovered an object with 2.5 times the mass of the Sun by observing pulsars orbiting around it. A pulsar is a neutron star that emits pulses of light at regular millisecond intervals due to a strong magnetic field.

As predicted by Albert Einstein's theory of relativity, pulsars emit light with great regularity, but very large nearby objects can distort these rhythms. Dr. Barr and his team were able to calculate the mass of the pulsar's partner by observing the pulsar's pulses for more than a year using his MeerKAT radio telescope in South Africa.

“What we've discovered in this binary system appears to go beyond that [upper limit for neutron star mass]This suggests that there is some new physics going on here and that this is either a new type of star, or simply a black hole, the lightest stellar-mass black hole yet discovered. “There will be,” Barr said.

Pulsars are located in globular clusters, which are dense regions of stars and some rare objects that can pass close to each other. These unusual interactions could explain the mysterious object, Barr said.

If it's a black hole, researchers will be able to test theories of gravity that weren't possible before. “A pulsar is just a ridiculously accurate measuring device in orbit around a black hole, but it's not going anywhere. It's going to be around for the next billion years,” Barr says. “So this is an incredibly stable and natural test bed for investigating the physics of black holes.”

“If it's a neutron star, it would be more massive than any neutron star we've ever seen,” he says. Christine Dunn At Durham University, UK. “This actually tells us about the ultimate density that a star can support before it collapses under its own gravity and becomes a black hole. We need to understand the physics of matter at such extreme densities. I don't know what the limits are.”

Barr and his team plan to observe the pulsar with other telescopes over the next few years, looking for clues about what the object is. If it were a black hole, we would see the pulsar's orbit change over time, as the black hole dragged through spacetime around it, much like a ship dragging a small boat behind it. Or if it's a neutron star, more sensitive instruments might be able to detect the light.

topic:

Source: www.newscientist.com