Tag Archives: pulsar

Unlocking the Secrets: Astronomers Decode Zebra Stripes of the Crab Pulsar

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Recent findings from the University of Kansas have unraveled a long-standing astrophysical mystery, revealing how the intricate interplay of gravity and magnetospheric plasma divides the radio emissions of a club pulsar—a remnant of the supernova witnessed by ancient astronomers in 1054 AD—into perfectly aligned “stripes.”

This composite image showcases the Crab Nebula, with the club pulsar centrally positioned. Image credit: X-ray – NASA / CXC / ASU / J. Hester et al.; Optics – NASA / HST / ASU / J. Hester et al.

In 1054 AD, Chinese astronomers documented an exceptionally bright new star, the most luminous object in the night sky after the moon, visible even in broad daylight for 23 days. This spectacular celestial event was also noted by Japanese, Arabian, and Native American astronomers.

Today, the Crab Nebula, found where this bright star once shone, is cataloged as Messier 1 (M1) or NGC 1952, located approximately 6,500 light-years away in the Taurus constellation.

Initially identified in 1731 by British physician and astronomer John Beavis, the Crab Nebula was later rediscovered in 1758 by French astronomer Charles Messier. Its name, reflecting its appearance, is derived from a painting by Irish astronomer Lord Rose in 1844.

The central star of the Crab Nebula is the Crab Pulsar, scientifically known as PSR B0531+21.

Due to their proximity and visibility, studying the Crab Nebula and its pulsars offers astronomers vital insights into the nature of nebulae, supernovae, and neutron stars.

“Gravity alters the shape of spacetime,” states Professor Mikhail Medvedev, one of the study’s authors.

“In the presence of a gravitational field, light does not travel in straight lines because space itself is curved,” he explains.

“What seems straight in flat spacetime appears curved under strong gravitational influence. Hence, gravity functions as a lens in curved spacetime.”

While gravitational lensing has often been discussed in relation to black holes, this case uniquely illustrates a “tug of war” between plasma and gravity creating the observed signals.

“In black hole imagery, gravity solely shapes the structure,” notes Professor Medvedev.

“In contrast, both gravity and plasma are at play in the club pulsar. This research presents a novel application of this combined effect.”

“An intriguing pattern emerges in the pulsar’s spectrum,” Professor Medvedev adds.

“Unlike a conventional broad spectrum like sunlight—which offers a continuous range of colors—the Crab’s high-frequency interpulses display discrete spectral bands. It’s like observing a rainbow with only selected ‘colors’ visible, leaving significant gaps in between.”

A large mosaic image of the Crab Nebula, a six-light-year wide remnant of a supernova explosion. Documented by Japanese, Chinese, and Native American astronomers around 1054 AD. Image credit: NASA / ESA / J. Hester / A. Loll, Arizona State University.

Typically, pulsar radio emissions are broader, noisier, and less organized compared to those from club pulsars.

“In the case of club pulsars, the stripes are exceptionally distinct, contrasting sharply with the complete darkness that separates them,” explains Professor Medvedev.

“There are shining bands and voids in between, with no gradual transition. No other pulsar displays this kind of banding. This uniqueness makes the club pulsar both intriguing and complex to comprehend.”

While former models could replicate the striped pattern, they failed to account for the high contrast actually seen in club pulsars.

Professor Medvedev has found that the plasma material surrounding the club pulsar contributes to the diffraction of electromagnetic pulses, which significantly influences the neutron star’s distinct zebra pattern.

By integrating Einstein’s theory of gravity into his analysis, Medvedev discovered its crucial role in shaping the club pulsar’s zebra stripe pattern.

“Prior theoretical models could reproduce the striped pattern, but not the observed contrast. Including gravity bridged that gap,” asserts Professor Medvedev.

“The plasma in a pulsar’s magnetosphere acts as a defocusing lens, while gravity serves as a focusing lens. Plasma tends to scatter light rays, whereas gravity draws them inward. When these dual effects converge, certain paths will offset each other.”

The synergy between defocused magnetospheric plasma and focusing gravity creates in-phase and out-of-phase interference bands of radio intensity, producing zebra stripes in club pulsars.

“The nature of symmetry suggests there are at least two pathways for light,” Medvedev observes.

“When two nearly identical paths converge on an observer, they create an interferometer. The signals amalgamate, reinforcing each other at specific frequencies (in phase) to yield bright bands, while at others (out of phase), they cancel each other out, generating darkness. This concept encapsulates the essence of interference patterns.”

“Little additional physics appears necessary to qualitatively explain the stripes.”

“Yet, quantitative enhancements could be implemented; the current model includes gravity in a static, lowest-order approximation.”

“Since pulsars rotate, incorporating rotational effects might lead to significant quantitative, if not qualitative, changes.”

The new research is set to be published in the Plasma Physics Journal.

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Mikhail V. Medvedev. 2026. Theory of the dynamic spectrum of club pulsar high-frequency interpulse stripes. Plasma Physics Journal, in press. arXiv: 2602.16955

Source: www.sci.news

Webb Discovers Unique Helium and Carbon-Rich Atmosphere on Exoplanet Orbiting Pulsar

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PSR J2322-2650b, an enigmatic Jupiter-mass exoplanet orbiting the millisecond pulsar PSR J2322-2650, exhibits an unusual atmosphere primarily composed of helium and carbon, presenting a new phenomenon never observed before.

Artist’s concept of PSR J2322-2650b. Image credit: NASA/ESA/CSA/Ralf Crawford, STScI.

“This discovery was completely unexpected,” stated Dr. Peter Gao, an astronomer at the Carnegie Earth and Planetary Institute.

“After analyzing the data, our immediate reaction was, ‘What on Earth is this?’ It contradicted all our expectations.”

“This system is fascinating because we can see the planet lit by its star, yet the star itself is invisible,” explained Dr. Maya Bereznay, a candidate at Stanford University.

“This allows us to capture exceptionally clear spectra, enabling us to study the system in a much more detailed way than we typically do with other exoplanets.”

“This planet orbits a truly unique star—it’s as massive as the sun but as compact as a city,” remarked Dr. Michael Chan from the University of Chicago.

“This represents a new kind of planetary atmosphere never before observed. Instead of the typical molecules like water, methane, and carbon dioxide, we detected carbon molecules, particularly C.3 and C2.”

Molecular carbon is exceedingly rare; at temperatures exceeding 2,000 degrees Celsius, carbon typically bonds with other atoms in the atmosphere.

Out of around 150 planets studied both within and beyond our solar system, none have showcased detectable molecular carbon.

“Did this form as a typical planet? Certainly not, due to its starkly different composition,” Dr. Zhang stated.

“Could it have been created by stripping the outer layers of a star, like what happens in a conventional black widow system? Likely not, as nuclear processes do not yield pure carbon.”

“Envisioning how this drastically carbon-rich composition came to be is quite challenging. All known formation theories seem to be excluded.”

The authors suggest an intriguing phenomenon that might occur in such a unique atmosphere.

“As the companion star cools, the carbon and oxygen mixture within begins to crystallize,” explained Roger Romani, an astronomer at Stanford University and the Kavli Institute for Particle Astrophysics and Cosmology.

“What we observed was pure carbon crystals rising to the surface and blending with the helium.”

“Yet, there must be a mechanism to prevent the oxygen and nitrogen from mixing in. This is where the mystery deepens.”

“However, it’s intriguing not to have all the answers. I’m eager to uncover more about the peculiarities of this atmosphere. Solving these enigmas will be remarkable.”

For more information, refer to the paper published in Astrophysics Journal Letter.

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michael chan et al. 2025. The carbon-rich atmosphere of a windy pulsar planet. APJL 995, L64; doi: 10.3847/2041-8213/ae157c

Source: www.sci.news

Is Pulsar Light the Key to Solving the Dark Matter Mystery?

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New research explores the possibility that dark matter is composed of theoretical particles called axions, and focuses on detecting them through additional light from pulsars. Although axions have not yet been confirmed in early observations, this research is critical to understanding dark matter.

A central question in the ongoing search for dark matter is: What is dark matter made of? One possible answer is that dark matter is made up of particles known as axions. A recent study by astrophysicists at the University of Amsterdam and Princeton University suggests that if dark matter is indeed made of axions, it could manifest itself in the form of subtle additional glow emanating from pulsating stars.

Dark matter may be the most sought-after building block in our universe. Remarkably, this mysterious form of matter, so far undetectable by physicists and astronomers, is thought to make up a huge portion of what exists on Earth. It is suspected that more than 85% of the matter in the universe is “dark”, and at the moment it is only recognized by the gravitational force it exerts on other celestial bodies. Naturally, scientists want to look directly detect its existence rather than just inferring it from gravitational effects. And of course they want to know what of course, solve two problems One thing is clear: dark matter cannot be the same kind of matter that makes up you and me. If so, dark matter would simply behave like ordinary matter. Dark matter will form star-like objects, will glow, and will no longer be “dark.” So scientists are looking for something new, a type of particle that no one has detected yet, and perhaps one that only interacts very weakly with the types of particles we know about.

One common hypothesis is that dark matter may be made of: Axion. This hypothetical type of particle was first introduced in the 1970s when he solved a problem that had nothing to do with dark matter. The separation of positive and negative charges inside a neutron, one of the building blocks of a normal atom, turns out to be unexpectedly small. Of course, scientists wanted to know why. It turns out that the presence of a previously undetected type of particle that interacts very weakly with components of neutrons can cause just such an effect. Frank Wilczek, who later won the Nobel Prize, came up with the name for this new particle. Axion – as well as similar to another particle name such as protons, neutrons, and electrons. photon, but it’s also inspired by the laundry detergent of the same name. Axion existed to solve problems. In fact, it might clean up the two even if it’s not detected. Several theories about elementary particles, including string theory, one of the leading candidate theories for unifying all the forces in nature, seem to predict the possibility of axion-like particles.

Fortunately, there appears to be a way out of this conundrum for axions. If the theory predicting axions is correct, not only would axions be expected to be produced in large quantities in the universe, but some axions could also be converted to light in the presence of strong electromagnetic fields. If there is light, we can see. Could this be the key to detecting axions and, by extension, dark matter? To answer this question, scientists first had to ask themselves where in the universe the strongest known electric and magnetic fields occur. The answer is known in the region around rotating neutron stars. pulsar. These pulsars (short for “pulsating stars”) are dense objects with a mass about the same as the Sun, but a radius about 100,000 times smaller, or only about 10 km. Because pulsars are so small, they rotate at enormous frequencies and emit bright, narrow beams of radio radiation along their axis of rotation. Just like a lighthouse pulsarThe beam can sweep across the Earth, making it easy to observe the pulsating star. But the pulsar’s massive rotation does more than that. it is, neutron star It turns into a very powerful electromagnet. That could mean Pulsar is a highly efficient axion factory. The average pulsar can produce 50 orders of magnitude axions per second. Because of the strong electromagnetic fields surrounding pulsars, some of these axions can be converted into observable light.

As always in science, carrying out such observations in practice is, of course, not so easy. The light emitted by axions (which can be detected in the form of radio waves) is only a fraction of the total light these bright cosmic lighthouses send back to us. Much less can we quantify the difference and turn it into a measurement of the amount of dark matter. This is exactly what a team of physicists and astronomers are currently doing. Through a collaboration between the Netherlands, Portugal, and the United States, the research team has uncovered details about how axions are created, how axions escape the neutron star’s gravity, and…

First observational tests were performed on the theory and simulation results…referencesystem, simulate a subtle glow

Next, first observational tests were performed on the theory and simulation results…referencesystem to show that it is very unlikely that axions are a component of…s

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Source: scitechdaily.com