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In search for red aurorae in ancient Japan

Ryuho Kataoka, a Japanese auroral scientist, played a seminal role in searching for evidence of super-geomagnetic storms in the past using historical methods

Karthik Vinod

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Professor Ryuho Kataoka in his office at NIPR, with the fan-shaped painting behind him, Picture courtesy: RK Works

Auroras seen on Earth are the end of a complex process that begins with a violent, dynamic process deep within the sun’s interior.

However, studying the depths of the sun is no easy task, even for scientists. The best they can do is to observe the surface using space-based telescopes. One problem that scientists are attempting to solve is how a super-geomagnetic storm on Earth comes to being. These geomagnetic storms find their roots in sunspots, that are acne-like depressions on the sun’s surface. As the sun approaches the peak of its 11-year solar cycle, these sunspots, numbering in the hundreds, occasionally release all that stored magnetic energy into deep space, in the form of coronal mass ejections (CMEs) (which are hot wisps of gas superheated to thousands of degrees).

If the earth lies in the path of an oncoming CME, the energy release from their resultant magnetic field alignment can cause intense geomagnetic storms and aurorae on Earth.

This phenomenon, which is astrophysical and also electromagnetic in nature, can have serious repercussions for our modern technological society.

Super-geomagnetic storms, a particularly worse form of geomagnetic storm, can induce power surges in our infrastructure, causing power outages that can plunge the world into darkness, and can cause irreversible damages to our infrastructure. The last recorded super-geomagnetic storm event occurred more than 150 years ago. Known as the Carrington event, the storm destroyed telegraph lines across North America and Europe in 1859. The risk for a Carrington-class event to happen again was estimated to be 1 in 500-years, which is quite low, but based on limited data. Ramifications are extremely dangerous if it were to ever happen.

However, in the past decade, it was learnt that such super-geomagnetic storms are much more common than scientists had figured. To top it all, it wasn’t just science, but it was a valuable contribution by art – specifically ancient Japanese and Chinese historical records that shaped our modern understanding of super-geomagnetic storms.

Ryuho Kataoka, a Japanese space physicist, played a seminal role in searching for evidence of super-geomagnetic storms in the past using historical methods. He is presently an associate professor in physics, holding positions at Japan’s National Institute of Polar Research, and The Graduate University for Advanced Studies.

“There is no modern digital dataset to identify extreme space weather events, particularly super-geomagnetic storms,” said Professor Kataoka. “If you have good enough data, we can input them into supercomputers to do physics-based simulation.”

However, sunspot records go until the late 18th century when sunspots were actively being cataloged. In an effort to fill the data gap, Professor Kataoka decided to be at the helm of a very new but promising interdisciplinary field combining the arts with space physics. “The data is limited by at least 50 years,” said Professor Kataoka. “So we decided to search for these red vapor events in Japanese history, and see the occurrence patterns … and if we are lucky enough, we can see detailed features in these lights, pictures or drawings.” Until the summer of 2015, Ryuho Kataoka wasn’t aware of how vast ancient Japanese and Chinese history records really were.

In the past 7 years, he’s researched a very specific red aurora, in documents extending to more than 1400 years. “Usually, auroras are known for their green colors – but during the geomagnetic storm, the situation is very different,” he said. “Red is of course unusual, but we can only see red during a powerful geomagnetic storm, especially in lower latitudes. From a scientific perspective, it’s a very reasonable way to search for red signs in historical documents.”

A vast part of these historical red aurora studies that Professor Kataoka researched came from literature explored in the last decade by the AURORA-4D collaboration. “The project title included “4D”, because we wanted to access records dating back 400 years back during the Edo period,” said Professor Kataoka.

“From the paintings, we can identify the latitude of the aurora, and calculate the magnitude or amplitude of the geomagnetic storm.” Clearly, paintings in the Edo period influenced Professor Kataoka’s line of research, for a copy of the fan-shaped red aurora painting from the manuscript Seikai (which translates to ‘stars’) hangs on the window behind his office desk at the National Institute of Polar Research.

The painting fascinated Professor Kataoka, since it depicted an aurora that originated during a super-geomagnetic storm over Kyoto in 1770. However, the painting did surprise him at first, since he wondered whether the radial patterns in the painting were real, or a mere artistic touch to make it look fierier. “That painting was special because this was the most detailed painting preserved in Japan,” remarked Professor Kataoka. “I took two years to study this, thinking this appearance was silly as an aurorae scientist. But when I calculated the field pattern from Kyoto towards the North, it was actually correct!”

Fan-shaped red aurora painting from the ‘Seikai’, dated 17th September, 1770; Picture Courtesy: Matsusaka City, Mie Prefecture.

The possibility to examine and verify historical accounts using science is also a useful incentive for scholars of Japanese literature and scientists partaking in the research.

“This is important because, if we scientists look at the real National Treasure with our eyes, we really know these sightings recorded were real,” said Professor Kataoka. “The internet is really bad for a survey because it can easily be very fake,” he said laughing. It’s not just the nature in which science was used to examine art – to examine Japanese “national treasures” that is undoubtedly appealing, but historical accounts themselves have contributed to scientific research directly.

“From our studies, we can say that the Carrington class events are more frequent than we previously expected,” said Professor Kataoka. There was a sense of pride in him as he said this. “This Carrington event is not a 1 in 200-year event, but as frequent as 1 in 100 years.” Given how electricity is the lifeblood of the 21st century, these heightened odds do ingrain a rather dystopian society in the future, that is ravaged by a super-geomagnetic storm.

Professor Kataoka’s work has found attention within the space physics community. Jonathon Eastwood, Professor of Physics at Imperial College London said to EdPublica, “The idea to use historical information and art like this is very inventive because these events are so rare and so don’t exist as information in the standard scientific record.”

There’s no physical harm from a geomagnetic storm, but the threat to global power supply and electronics is being increasingly recognized by world governments. The UK, for instance, identified “space weather” as a natural hazard in its 2011 National Risk Register. In the years that followed, the government set up a space weather division in the Met Office, the UK’s foremost weather forecasting authority, to monitor and track occurrences of these coronal mass ejections. However, these forecasts, which often supplement American predictions – namely the National Oceanic and Atmospheric Administration (NOAA) – have failed to specify previously where a magnetic storm could brew on Earth, or predict whether a coronal mass ejection would ever actually strike the Earth.

The former occurred during the evacuation process for Hurricane Irma in 2017, when amateur radio ham operators experienced the effects of a radio blackout when a magnetic storm affected the communications network across the Caribbean. The latter occurred on another occasion when a rocket launch for SpaceX’s Starlink communication satellites was disrupted by a mild geomagnetic storm, costing SpaceX a loss of over $40 million.

Professor Kataoka said he wishes space physicists from other countries participate in similar interdisciplinary collaborations to explore their native culture’s historical records for red aurora sightings. He said the greatest limitation of the AURORA-4D collaboration was the lack of historical records from other parts of the world. China apparently boasts a history of aurora records longer than Japan, with a history lasting before Christ himself. “Being Japanese, I’m not familiar with British, Finnish or Vietnamese cultures,” said Professor Kataoka. “But every country has literature researchers and scientists who can easily collaborate and perform interdisciplinary research.” And by doing so, it’s not just science which benefits from it, but so is ancient art whose beauty and relevance gains longevity.

Karthik is a science writer, and co-founder of Ed Publica. He writes and edits the science page. He's also a freelance journalist, with words in The Hindu, a prominent national newspaper in India.

Space & Physics

MIT team finds the smallest asteroids ever detected in the main belt

This marks the first time such small asteroids in the asteroid belt have been spotted, potentially leading to better tracking of near-Earth objects that could pose a threat

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Credits: Image: Ella Maru and Julien de Wit

Asteroids that could potentially impact Earth vary greatly in size, from the catastrophic 10-kilometer-wide asteroid that caused the extinction of the dinosaurs to much smaller ones that strike far more frequently. Now, an international team of researchers, led by physicists at MIT, has discovered a new way to spot the smallest asteroids in our solar system’s main asteroid belt, which could provide critical insights into the origins of meteorites and planetary defense.

The team’s breakthrough approach allows astronomers to detect decameter asteroids—those just 10 meters across—much smaller than those previously detectable, which were about one kilometer in diameter. This marks the first time such small asteroids in the asteroid belt have been spotted, potentially leading to better tracking of near-Earth objects that could pose a threat.

“We have been able to detect near-Earth objects down to 10 meters in size when they are really close to Earth,” said lead author Artem Burdanov, a research scientist at MIT’s Department of Earth, Atmospheric and Planetary Sciences. “We now have a way of spotting these small asteroids when they are much farther away, so we can do more precise orbital tracking, which is key for planetary defense.”

The team used their innovative method to detect over 100 new decameter asteroids, ranging from the size of a bus to several stadiums wide. These are the smallest asteroids ever found in the main asteroid belt, located between Mars and Jupiter, where millions of asteroids orbit.

The findings, published today in Nature, have the potential to improve asteroid tracking efforts, which are critical for understanding the risk of future impacts. Scientists hope that the method could be applied to identify asteroids that may one day approach Earth.

The research team, which includes MIT planetary science professors Julien de Wit and Richard Binzel, as well as collaborators from the University of Liege, Charles University, and the European Space Agency, among others, utilized the James Webb Space Telescope (JWST) for their discovery. JWST’s sensitivity to infrared light made it an ideal tool for detecting the faint infrared emissions of asteroids, which are far brighter at these wavelengths than in visible light.

The team’s approach also relied on an imaging technique called “shift and stack,” which involves aligning multiple images of the same field of view to highlight faint objects like asteroids. This technique was originally developed for exoplanet research but was adapted for asteroid detection.

The researchers believe that these new findings will help improve our understanding of asteroid population

By processing over 10,000 images of the TRAPPIST-1 system—collected to study the planets in that distant star system—the researchers identified eight known asteroids and an additional 138 new ones. These newly discovered asteroids are the smallest main belt asteroids ever detected, with diameters as small as 10 meters.

“This is a totally new, unexplored space we are entering, thanks to modern technologies,” Burdanov said. “It’s a good example of what we can do as a field when we look at the data differently. Sometimes there’s a big payoff, and this is one of them.”

The researchers believe that these new findings will help improve our understanding of asteroid populations, including the many small objects that result from collisions among larger asteroids. Miroslav Broz, a co-author from Charles University in Prague, emphasized the importance of studying these decameter asteroids to model the creation of asteroid families formed from larger, kilometer-sized collisions.

De Wit, a co-author, highlighted the significance of the discovery: “We thought we would just detect a few new objects, but we detected so many more than expected, especially small ones. It is a sign that we are probing a new population regime, where many more small objects are formed through cascades of collisions.”

(With inputs from MIT)

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NASA’s IXPE Helps Unveil Secrets of Black Hole’s X-ray Outburst

Swift J1727 is the first such black hole to be observed by IXPE as it went through the stages of an X-ray outburst, from its onset to its peak and eventual return to inactivity

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This illustration shows NASA’s Imaging X-ray Polarimetry Explorer (IXPE) spacecraft, at lower left, observing the newly discovered binary system Swift J1727.8-1613 from a distance. Credit: Marie Novotná

US space agency NASA’s Imaging X-ray Polarimetry Explorer (IXPE) has provided new insights into the structures around a stellar-mass black hole, enhancing our understanding of the swirling disk of material and the shifting plasma region known as the corona. The black hole is part of the binary system Swift J1727.8-1613, and was discovered during an extraordinary brightening event in the summer of 2023. This outburst briefly made the black hole outshine nearly all other X-ray sources, according to NASA.

Swift J1727 is the first such black hole to be observed by IXPE as it went through the stages of an X-ray outburst, from its onset to its peak and eventual return to inactivity. Scientists say the data collected during this outburst offers first-time insight into the behaviour and evolution of black hole X-ray binary systems.

Astrophysicist Alexandra Veledina, from the University of Turku in Finland, described the event as “incredibly quick.” From the initial detection of the outburst, Swift J1727 took only days to reach its peak. By that time, IXPE and other telescopes were already gathering crucial data to track the outburst’s progression. “It was exhilarating to observe the outburst all the way through its return to inactivity,” Veledina added.

The outburst, which briefly surpassed the brightness of the Crab Nebula (the standard X-ray reference), lasted until late 2023. Notably, this event occurred just 8,800 light-years away from Earth, making it an exceptional discovery in terms of both brightness and proximity. The system was named after the Swift Gamma-ray Burst Mission, which initially detected the event on August 24, 2023, using its Burst Alert Telescope.

The findings, published in The Astrophysical Journal and Astronomy & Astrophysics, gives a deeper understanding of the dynamics of black hole systems and the role of X-ray binaries in the broader cosmic landscape.

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New antenna design could help detect faint cosmological signals

This could revolutionise our ability to detect the faint signals of Cosmological Recombination Radiation (CRR)

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Image credit: PIB

In an intriguing development, scientists at the Raman Research Institute (RRI) in Bangalore, India, have developed a novel antenna design that could revolutionise our ability to detect the faint signals of Cosmological Recombination Radiation (CRR).

These signals, which are crucial for understanding the thermal and ionization history of the Universe, have so far remained undetected due to their elusive nature. The newly designed antenna is capable of measuring signals in the 2.5 to 4 Gigahertz (GHz) frequency range, which is optimal for detecting CRR, a signal that is approximately one billion times fainter than the Cosmic Microwave Background (CMB).

As per available sources, the universe is approximately 13.8 billion years old, and in its earliest stages, it was extremely hot and dense. During this time, the Universe was composed of a plasma of free electrons, protons, and light nuclei such as helium and lithium. The radiation coexisting with this matter has been detected today as the CMB, which holds vital information about the early cosmological and astrophysical processes.

One such process, known as the Epoch of Recombination, marks the transition from a fully ionized primordial plasma to mostly neutral hydrogen and helium atoms. This transition emitted photons, creating the Cosmological Recombination Radiation (CRR), which distorts the underlying CMB spectrum. Detecting these faint CRR signals would provide a wealth of information about the Universe’s early ionization and thermal history and could even offer the first experimental measurements of helium abundance before it was synthesized in the cores of stars.

However, detecting CRR is a significant challenge because these signals are extremely weak—about nine orders of magnitude fainter than the CMB. To address this, scientists need highly sensitive instruments that can isolate these signals from the vast cosmic noise surrounding them.

To this end, researchers from RRI, including Mayuri Rao and Keerthipriya Sathish, along with Debdeep Sarkar from the Indian Institute of Science (IISc), have developed an innovative ground-based broadband antenna designed to detect signals as faint as one part in 10,000. Their design is capable of making sky measurements in the 2.5 to 4 GHz range, the frequency band most suitable for CRR detection.

According to Keerthipriya Sathish, the lead author of the study, “For the sky measurements we plan to perform, this broadband antenna offers the highest sensitivity compared to other antennas designed for the same bandwidth. The antenna’s frequency-independent performance across a wide range and its smooth frequency response are features that set it apart from conventional designs.”

The antenna is compact and lightweight, weighing just 150 grams, with a square shape measuring 14 cm by 14 cm.

The proposed antenna is a dual-polarized dipole antenna with a unique four-arm structure shaped like a fantail. This design ensures that the antenna maintains the same radiation pattern across its entire operational bandwidth, with a mere 1% variation in its characteristics. This is crucial for distinguishing spectral distortions from galactic foregrounds. The antenna’s custom design allows it to “stare” at the same patch of sky throughout its full operational range of 1.5 GHz (from 2.5 to 4 GHz), which is key to separating the CRR signals from other cosmic noise.

The antenna is compact and lightweight, weighing just 150 grams, with a square shape measuring 14 cm by 14 cm. It is made using a low-loss dielectric flat substrate on which the antenna is etched in copper, while the bottom features an aluminum ground plate. Between these plates lies a radio-transparent foam layer that houses the antenna’s connectors and receiver base.

With a sensitivity of around 30 millikelvin (mK) across the 2.5-4 GHz frequency range, the antenna is capable of detecting tiny temperature variations in the sky. Even before being scaled to a full array, this antenna design is expected to provide valuable first scientific results when integrated with a custom receiver. One of the anticipated experiments is to study an excess radiation reported at 3.3 GHz, which has been speculated to result from exotic phenomena, including dark matter annihilation. These early tests will help refine the antenna’s performance and guide future design improvements aimed at achieving the sensitivity required for CRR detection.

The researchers plan to deploy an array of these antennas in radio-quiet areas, where radio frequency interference is minimal or absent. The antenna’s design is straightforward and can be easily fabricated using methods similar to those employed in Printed Circuit Board (PCB) manufacturing, ensuring high machining accuracy and consistency for scaling up to multiple-element arrays. The antenna is portable, making it easy to deploy in remote locations for scientific observations.

The team is already looking ahead, planning further improvements to achieve even greater sensitivity, with a long-term goal of detecting CRR signals at sensitivities as low as one part per billion. With this innovative antenna design, the team hopes to make significant strides toward uncovering the secrets of the early Universe and its formation.

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