Category: 7. Science

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Using the world’s most advanced radio telescopes, astronomers have discovered a spinning dead star so rare, strange and unique that they have dubbed it a “cosmic unicorn.” The unique properties of this object, CHIME J1634+44, challenge our current understanding of spinning dead stars and their environments.

CHIME J1634+44, also known as ILT J163430+445010 (J1634+44), is part of a class of objects called Long Period Radio Transients (LPTs). LPTs are a newly found and mysterious type of celestial body that emits bursts of radio waves that repeat on timescales of minutes to hours. That’s significantly longer than the emission of standard pulsars, or rapidly spinning neutron star stellar remains that sweep beams of radiation across the cosmos as they spin.

But as strange as all LPTs are, CHIME J1634+44 still stands out. Not only is it the brightest LPT ever seen, but it is also the most polarized. Additionally, its pulses of radiation seem highly choreographed. And what really stands out about CHIME J1634+44 is the fact that it is the only LPT astronomers have ever seen whose spin is speeding up.

“You could call CHIME J1634+44 a ‘unicorn’ even among other LPTs. The bursts seem to repeat either every 14 minutes or 841 seconds — but there is a distinct secondary period of 4206 seconds, or 70 minutes, which is exactly five times longer,” team leader Fengqiu Adam Dong, a Jansky Fellow at the Green Bank Observatory (GBO), said in a statement. “We think both are real, and this is likely a system with something orbiting a neutron star.”

The team discovered the unusual traits of CHIME J1634+44 using ground-based instruments including the Green Bank Telescope, the Very Large Array (VLA), the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Fast Radio Burst and Pulsar Project, the NASA-operated space-based observatory, and the Neil Gehrels Swift Observatory (Swift). The object was, in fact, simultaneously discovered by a separate team of astronomers at ASTRON, the Netherlands Institute for Radio Astronomy, using the LOFAR (Low Frequency Array) radio telescope.

While the team led by Dong believes a stellar remnant at the heart of CHIME J1634+44 is a neutron star, the ASTRON team, captained by astronomer Sanne Bloot, refers to it as J1634+44 and think it is a white dwarf. What both teams agree on, though, is just how strange this LPT is.

This unicorn is speeding up by feeding on a star

Both white dwarfs and neutron stars are dead stars created when stars of differing masses run out of the fuel supplies they need for nuclear fusion at their cores. Once that fuel is over, the stars can no longer support themselves against their own immense gravities.

Neutron stars are stellar remnants that form when massive stars, with masses at least eight times that of the sun, reach the end of their lives and collapse. Smaller stars closer in mass to the sun leave behind a slightly less extreme stellar remnant called a “white dwarf.”

Though most of the mass of these dying massive stars is shed in supernova explosions, the cores of the stars maintain a mass between one and two times that of the sun. This is crushed down to a width of around 12 miles (20 kilometers), creating matter so dense that if a teaspoon of neutron star “stuff” were scooped out and brought to Earth, it would weigh 10 million tons (equal to stacking 85,000 blue whales on a teaspoon).

This collapse has another extreme consequence. The dying star maintains its angular momentum, meaning that when its radius is rapidly reduced during collapse, it speeds up greatly. Though the collapse of white dwarfs is less extreme, it also causes an increase in spin speed due to the conservation of angular momentum.

An Earth-based example of this is an ice skater pulling in their arms to increase the speed of their spin.

What this means is some young neutron stars can spin as fast as 700 times every second. However, as neutron stars and white dwarfs age, they should slow down as they lose energy. That’s why no matter what CHIME J1634+44 is, the fact that it is speeding up its spin is very strange.

There is a way neutron stars or white dwarfs can increase their spin speed, or “spin up” after their birth. It depends on whether they have a close companion star.

As such, the new study’s team suspects CHIME J1634+44 may actually be composed of two stellar objects orbiting each other in a tight binary format. The ASTRON team proposes that this companion is either another stellar remnant (like a white dwarf or neutron star) or is a “failed star” brown dwarf — a body that forms like a star but fails to gather enough mass to trigger the nuclear fusion that defines what a star is.

As these bodies swirl around each other, they would emit ripples in spacetime called gravitational waves. This carries away angular momentum and causes the two stellar bodies to move closer together. This would cause the period of the binary to appear as if it is shortening. This type of orbital tightening has been witnessed before by astronomers in white dwarf binaries.

CHIME J1634+44 gets stranger, however.

Its radio bursts are 100% circularly polarized. This means the electromagnetic waves escaping J1634+44 rotate in a circle (like a corkscrew) as they propagate.

Thus, the electromagnetic radiation escaping CHIME J1634+44 twists around in a perfect spiral as it moves away from its source. Not only is that extremely rare, but it is something that has never been seen in bursts of radiation from either neutron stars or white dwarfs.

That implies the radio wave blasts of CHIME J1634+44 are being generated in a way that is unique for this dead star.

Astronomers have a mystery on their hands with this dead star

What is also weird about these pulses is the fact that they arrive in pairs, but only when the dead star in the CHIME J1634+44 binary has spun several times without emitting a burst.

“The time between pulse pairs seems to follow a choreographed pattern,” team member and ASTRON astronomer Harish Vedantham said in a statement. “We think the pattern holds crucial information about how the companion triggers the white dwarf to emit radio waves.

“Continued monitoring should help us decode this behavior, but for now, we have a real mystery on our hands.”

Related Stories:

— New kind of pulsar may explain how mysterious ‘black widow’ systems evolve

— Hear ‘black widow’ pulsar’s song as it destroys companion

—NASA X-ray spacecraft reveals secrets of a powerful, spinning neutron star

The research conducted by these astronomers not only reveals more about neutron stars, the universe’s most extreme stellar objects, but also hints at an exciting new phase for radio astronomy.

“The discovery of CHIME J1634+44 expands the known population of LPTs and challenges existing models of neutron stars and white dwarfs, suggesting there may be many more such objects awaiting discovery,” Dong concluded.

Both teams’ research was published on Thursday (July 17) in the journal Astronomy & Astrophysics.

Using the world’s most advanced radio telescopes, astronomers have discovered a spinning dead star so rare, strange and unique that they have dubbed it a “cosmic unicorn.” The unique properties of this object, CHIME J1634+44, challenge our current understanding of spinning dead stars and their environments.

CHIME J1634+44, also known as ILT J163430+445010 (J1634+44), is part of a class of objects called Long Period Radio Transients (LPTs). LPTs are a newly found and mysterious type of celestial body that emits bursts of radio waves that repeat on timescales of minutes to hours. That’s significantly longer than the emission of standard pulsars, or rapidly spinning neutron star stellar remains that sweep beams of radiation across the cosmos as they spin.

A first-of-its-kind video showing the ground cracking during a major earthquake is even more remarkable than previously thought. It not only captures a ground motion never caught on video before but also shows the crack curving as it moves.

This curvy movement has been inferred from the geological record and from “slickenlines” — scrape marks on the sides of faults — but it had never been seen in action, geophysicist Jesse Kearse, a postdoctoral researcher currently at Kyoto University in Japan, said in a statement.

Multiple space agencies plan to return astronauts to the Moon by the end of this decade. Along with commercial and international partners, these efforts aim to create infrastructure that will ensure a “sustained program of lunar exploration and development.” This includes NASA’s Artemis Program, China’s International Lunar Research Station (ILRS), and the ESA’s Moon Village, all of which consist of creating lunar habitats around the South Pole-Aitken Basin. Providing power for these bases is a significant challenge given the cycle of lunar day and night, which lasts for two weeks at a time.

Several promising technologies are being investigated to address this challenge, including Sterling Engines, which could power Space Nuclear Reactor Power Systems (SNRPS). However, many properties and design considerations must be considered before functional prototypes are built. In a recent paper, a team of Chinese scientists created an analytical model to evaluate different Sterling Engine designs and determine which is the most promising. Their work presents a Stirling cycle analysis method that more accurately captures the engine’s real-world operating behavior.

The study was led by Shang-Dong Yang, a Professor of Organic Chemistry with the College of Nuclear Technology and Automation Engineering (CNTAE) at the Chengdu University of Technology. He was joined by fellow researchers from the CNTAE and the Science and Technology on Reactor System Design Technology Laboratory at the Nuclear Power Institute of China. The paper that details their findings was published in Nuclear Science and Techniques.

A Stirling engine is a closed-cycle regenerative heat system that utilizes the expansion and contraction of gases (exposed to different temperatures) to convert heat energy into mechanical work. These engines are known for their high efficiency and versatility, making them prime candidates for advanced power systems in extraterrestrial environments. Unfortunately, predicting their potential performance in environments like the Moon and Mars remains difficult since real-world testing data is lacking.

In the meantime, scientists are forced to rely on theoretical models that take into account the thermodynamics of such a system. In this case, second-order analysis methods are used extensively to inform the design and thermodynamic analysis of Stirling engines. For their study, the team developed a simplified version that bridges thermodynamic cycles and engine operation by accounting for various energy dissipation factors, including shuttle heat loss, seal leakage, flow resistance, and finite piston speed.

These considerations are crucial when designing engines that can function and provide power to lunar and Martian habitats and other facilities necessary for working and living beyond Earth. As Prof. Fong explained in a EurekaAlert news release:

Our refined model offers a clearer picture of how various design parameters, such as regenerator porosity and working fluid choice, affect Stirling engine efficiency and power output. This advancement provides critical reference and data support for the application of Stirling engines in advanced compact energy systems.

The predictive capability of their model is also validated based on experimental data from existing Sterling engines, like the GPU-3 and the free-piston RE-1000. NASA developed these concepts during the 1970s to produce applications for future missions that would build on the accomplishments of the Apollo Program.

Prototype NASA 1kW Kilopower nuclear reactor for use in space and on planetary surfaces. Credit: NASA Glenn Research Center

The next step for the team is to leverage this model to explore dynamic operational scenarios like engine start-up and transient responses. This research could lead to prototypes generating electricity for compact nuclear reactors, which could be tested in simulated lunar and Martian conditions. With luck, the technology could assist in the creation of permanent human outposts on the Moon and provide applications for life here on Earth. Said Prof. Fong:

Future research will focus on understanding and managing thermal balance across all operational stages within an integrated reactor system, with particular attention to start-up in sensitive environments such as space. This includes investigating the influence of the heat pipe reactor’s output characteristics on the Stirling engine’s performance, efficiency, and stability.

Further Reading: Nature

Two black holes have collided far beyond the distant edge of the Milky Way, creating the biggest merger ever recorded by gravitational wave detectors.

The two phenomena, each more than 100 times the mass of the sun, had been circling each other before they violently collided about 10 billion light years from Earth.

Scientists at the Ligo Hanford and Livingston Observatories detected ripples in space-time from the collision just before 2pm UK time on 23 November 2023, when the two US-based detectors in Washington and Louisiana twitched at the same time.

Alongside their enormous masses, the signal, dubbed GW231123 after its discovery date, also showed the black holes spinning rapidly, according to researchers.

“This is the most massive black hole binary we’ve observed through gravitational waves, and it presents a real challenge to our understanding of black hole formation,” said Professor Mark Hannam, from Cardiff University and a member of the Ligo Scientific Collaboration.

open image in gallery

Gravitational-wave observatories have recorded around 300 black hole mergers.

Prior to GW231123, the heaviest merger detected was GW190521, whose combined mass was 140 times that of the sun. The latest merger produced a black hole up to 265 times more massive than the sun.

“The black holes appear to be spinning very rapidly — near the limit allowed by Einstein’s theory of general relativity,” said Dr Charlie Hoy from the University of Portsmouth.

“That makes the signal difficult to model and interpret. It’s an excellent case study for pushing forward the development of our theoretical tools.”

“It will take years for the community to fully unravel this intricate signal pattern and all its implications,” said Dr Gregorio Carullo, assistant professor at the University of Birmingham.

“Despite the most likely explanation remaining a black hole merger, more complex scenarios could be the key to deciphering its unexpected features. Exciting times ahead!”

Facilities like Ligo in the United States, Virgo in Italy, and KAGRA in Japan are engineered to detect the tiniest distortions in spacetime caused by violent cosmic events such as black hole mergers.

The fourth observing run began in May 2023, and data through January 2024 are scheduled for release later this summer.

“This event pushes our instrumentation and data-analysis capabilities to the edge of what’s currently possible,” says Dr Sophie Bini, a postdoctoral researcher at Caltech.

“It’s a powerful example of how much we can learn from gravitational-wave astronomy — and how much more there is to uncover.”

GW231123 is set to be presented at the 24th International Conference on General Relativity and Gravitation (GR24) and the 16th Edoardo Amaldi Conference on Gravitational Waves, held jointly as the GR-Amaldi meeting in Glasgow, from 14 to 18 July.

peak on July 29.

The Southern Delta Aquariid shower is active from July 18 to Aug. 12, as Earth passes through a trail of ancient debris that is suspected to have been shed by the 4-mile-wide (6.4 km) comet 96P Machholz. When this debris hits Earth’s atmosphere, the friction created by air molecules causes the particles to ignite, creating the visible streaks we see in the sky. The shower is at its strongest in the week surrounding its peak on July 29, at which time viewers could spot up to eight faint meteors per hour, according to NASA.

Stars of all ages and masses emit electromagnetic energy in different ways, and these emissions attract the attention of astronomers. Each of these emissions is a clue to how stars form, evolve, and even die. Young stars are known for their high luminosity and their high level of activity. They have strong stellar winds and powerful magnetic fields.

One of young stars’ most spectacular features are their jets. Their powerful magnetic fields play an important role in these jets, as the material travels along magnetic field lines. New research found magnetic fields around one massive young star with a distinctive circular polarization (CP) feature. This is the first time that CP has been detected around such a massive young star.

The research is “First Detection of Circular Polarization in Radio Continuum Toward a Massive Protostar,” and it’s published in The Astrophysical Journal Letters. The lead author is Amal G. Cheriyan, a PhD student at the Indian Institute of Space Science and Technology. The researchers used the National Radio Astronomy Observatory’s (NRAO) Karl G Jansky Very Large Array (VLA) in the USA to observe the CP.

“Polarization measurements provide strong constraints on magnetic fields in star-forming systems,” the authors write. “While magnetic field estimates of a few kG (kilogauss) have been obtained near the surfaces of low-mass protostars, there are no analogous measurements in the immediate vicinity of the surface of massive protostars.”

While all protostars are scientifically interesting, massive protostars attract attention because of the effects they have on their surroundings as they evolve. Their extreme luminosity and powerful stellar winds shape their surroundings in ways that lower-mass stars don’t. Their powerful UV radiation can ionize the interstellar medium, and their winds can carve out bubbles in it. They can heat the surrounding gas and make it turbulent, which inhibits star formation.

Astronomers have detected CP around low-mass protostars, and even around black holes, but never around such a high-mass protostar before. The young star is named IRAS 18162-2048, has about 10 solar masses, and is about 5,500 light-years away. IRAS 18162 “drives the largest known, highly collimated and most luminous jet in our Galaxy—the HH 80–81 jet,” the authors explain. HH 80-81 is a Herbig-Haro object, which are created when jets from young stars send ionized gas into nearby clouds of gas and dust in the ISM.

This Hubble Space Telescope image shows HH 80 (right) and HH 81 (left). Herbig-Haro objects are created when jets slam into the ISM. Since the ISM is clumpy, HH objects change over time. CC SA 4.0 Image Credit: https://commons.wikimedia.org/w/index.php?curid=132051483

Previous research from 2010 detected magnetized jets coming from HH 80-81, the first time they were ever detected, showing that protostars can have magnetized jets. This discovery builds on that, and is the first time that magnetic fields have been found coming directly form the protostar itself. While these fields have been detected around less massive protostars, finding them around massive protostars like IRAS 18162-2048 has been difficult.

Measuring the CP allows scientists to estimate the magnetic field close to the stellar surface. “However, no analogous measurements are available for massive protostars,” they write. “Massive protostars – stars that will evolve to have mass more than 8-10 times that of the Sun – are much harder to study. The circular polarization we’re looking for is very faint and sporadic, making such measurements very challenging,” explains lead author Cheriyan.

“This is the first inference of the magnetic field strength using circular polarization in radio waves from a massive protostar,” said Prof Sarita Vig of the Indian Institute of Space Science and Technology (IIST), who conceptualized the work.

CP has also been detected at active galactic nuclei. So detecting it at massive protostars draws a link between them, lower mass protostars, and black holes.

“The detection of circular polarization is an exceptionally rare and challenging feat – even in active galactic nuclei (AGNs), where conditions are extreme, but better investigated,” said Prof Nirupam Roy from the Indian Institute of Science (IISc).

“Observing it in the environment of a massive protostar, buried in dense gas and dust, is even more difficult, making this result very remarkable,” added Prof Samir Mandal of IIST.

Only a small number of OB stars, which IRAS 18162-2048 is on its way to becoming, have surface magnetic fields of several hundreds to thousands of gauss. It’s possible that these magnetic fields are fossils from earlier stages of the star’s life. This is called the fossil fields hypothesis.

“According to this theory, magnetic fields from the interstellar medium permeate molecular clouds, and as these clouds undergo gravitational collapse into protostars, the fields are both advected and amplified,” the researchers write in their paper. “This process can generate magnetic fields up to a few hundred gauss in massive stars, which is consistent with the observed results.”

This illustration shows the binary star HD 45166. Its primary star is extremely magnetic, and IRAS 18162-2048 could be on the path to becoming one of these magnetic stars. Image Credit: By P. Marenfeld, M. Zamani – https://noirlab.edu/public/images/noirlab2323a/, CC BY 4.0.

All stars have magnetic fields, but some stars have very strong and very stable magnetic fields that set them apart. IRAS 18162-2048 could end up becoming one of them. “Given the strength of the magnetic field estimated toward I18162, we speculate that I18162 could be a precursor to a massive magnetic star,” the researchers explain. As a result, the magnetic measurements of this star could help astrophysicists constrain and develop their models of star formation, even though the exact mechanism behind the CP is unclear.

Astrophysicists have thought for a long time that the same processes drive jets from stars and black holes. This research supports that, and is evidence of a universal jet-launching mechanism.

Key Facts

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Where Will The Northern Lights Be Visible?

The viewing line encompasses states and areas such as Alaska, northeastern Washington, northern Idaho, northeastern Montana, North Dakota and the Michigan Peninsula.

What’s The Best Way To See The Northern Lights?

Those looking to catch a glimpse of aurora borealis should do so between 10 p.m. and 2 a.m., the window of time generally considered to provide viewers with the right lighting conditions. Observers can increase their chances by going to vantage points and areas with clear skies and little to no light pollution.

What’s The Best Way To Photograph The Northern Lights?

Night mode and no flash is the best way for smartphone users to snap pictures of the northern lights. Those with traditional cameras should use low apertures, wide-angle lenses and tripods if possible.

Key Background

The northern lights have remained particularly active in the U.S. since last year and are expected to continue having a presence into 2026. The sun reached the peak of its 11-year cycle last year, representing an increase in solar flares and coronal mass ejections that contribute to frequent and stronger aurora borealis showings. The solar cycle will eventually taper off, leading to weaker auroral activity within the next two years.

Further Reading

Northern Lights Displays Hit A 500-Year Peak In 2024—Here’s Where You Could Catch Aurora Borealis In 2025 (Forbes)

Physicists with the USC Dornsife College of Letters, Arts and Sciences, Cornell University and collaborating institutions have created a microscopic device that can both detect and control the rapid “dance” of electron spins in antiferromagnetic materials – a leap that could enable a new generation of ultrafast, energy-efficient electronics.

The work was published this month in Science.

• Antiferromagnetic materials are solids in which electrons spin in opposite directions, canceling each other’s This zero-magnetism makes them fast, stable and immune to outside magnetic interference.
• Until now, scientists could only detect this quantum behavior using bulky lab equipment – making it hard to imagine practical uses in everyday tech.

Why it matters: Antiferromagnets can operate at mind-boggling speeds – trillions of cycles per second – and could support real-world applications that include:

• Ultra-secure, lightning-fast wireless communications, well beyond 5G speeds.
• Ultra-high-resolution medical imaging.
• Safer airport security scanning without X-rays.
• Nano-oscillators that convert a static voltage to high-frequency signals, useful in a wide range of applications, including advanced computers and sensors.

And it does all of this with a device just a few atoms thick, using only electric signals – no room-sized equipment required.

The work was made possible by funding from the National Science Foundation and the U.S. Department of Energy – two key supporters of fundamental research driving tomorrow’s technology.

The breakthrough: The team built a microscopic structure called a “tunnel junction” made of three, ultra-thin stacked layers of materials. This tiny device can do two key things:

1. Detect antiferromagnetic resonance – the natural vibration of opposing electron spins.
2. Tune that resonance electrically using a force called spin-orbit torque, which nudges the electron spins into motion.

What they’re saying: “This gives us a quantum-scale stethoscope and control knob in one,” said Kelly Luo, co-corresponding author and Gabilan Assistant Professor of Physics and Astronomy, Chemistry, and Chemical Engineering and Materials Science at USC Dornsife. “We’re able to listen to the spin dynamics – and then dial them up or down – using nothing but electric current.”

How it’s different: Previous methods for detecting antiferromagnetic behavior relied on bulky lab equipment and relatively large materials. This new device works at the micron scale – roughly 1,000 times smaller – making it the most compact, electrically tunable platform yet.

• “We’ve shrunk the technology down to a size that makes practical applications possible,” said Daniel Ralph, co-corresponding author and R. Newman Professor of Physics in Cornell’s College of Arts and Sciences. “That’s what makes this so exciting.”

A clever twist: At first, the team couldn’t tell which of the two magnetic layers was responsible for the signal – their behaviors were too closely linked.

Their solution? Twist the layers ever so slightly to break the symmetry. That allowed them to target just one layer with electric current while leaving the other unaffected.

“It was like trying to separate the sound of two violins playing the same note,” said lead author Thow Min Jerald Cham, formerly at Cornell and now David and Ellen Lee Postdoctoral Scholar at Caltech. “That tiny shift helped us tell them apart and control each one individually.”

What’s next? The researchers plan to develop nano-oscillators based on their device – tiny components that generate ultra-fast signals for applications in medical imaging, scientific instruments, telecommunications, quantum computing and more.

• They also want to explore “negative damping” – a phenomenon where, instead of fading out, the spin oscillations actually gain energy. That could allow the device to act as a powerful, terahertz radiation source in a footprint smaller than a grain of sand.

About the study

In addition to Luo, Ralph and Cham, study authors include Xiaoxi Huang of Cornell; Daniel Chica and Xavier Roy of Columbia University; and Kenji Watanabe and Takashi Taniguchi of Japan’s National Institute for Materials Science.