pulsation

It's like a sprint record: to break it, you need a perfect run-up. But for sub-millisecond pulsars, the run-up is too short. The fastest known pulsar, PSR J1748-2446ad, spins 716 times per second — faster than a kitchen blender. If it were the size of Earth, a point on its equator would move at about 0.24 times the speed of light. But why doesn't any pulsar spin even faster?

Picture a lighthouse on the shore at night. Its lamp is off almost all the time, but once every few days, for a split second, it blazes so brightly that the light is visible beyond the horizon.

Cepheids are stars that pulsate with remarkable regularity: their brightness changes like a lighthouse beam, and the pulsation period is linked to the star's average density. In binary systems where a Cepheid is eclipsed by its companion, astronomers can precisely measure the star's radius and mass.

The night sky looks calm, but in reality, invisible particles, cosmic rays, are constantly flying through us. Among them are electrons and their antimatter counterparts, positrons. When they collide with detectors on satellites or balloons, the instruments record their energy.

After a supernova explosion, a dense ball the size of a city remains at the center — a newborn neutron star. It is hot, compressed, and rings like a bell after being struck. These tremors, the star's oscillations, emit gravitational ripples that sensitive detectors on Earth can catch.

Pulsars are rapidly spinning neutron stars that emit radio pulses like a lighthouse. But some of them stay silent almost all the time, occasionally emitting a single pulse. Such objects are called rotating radio transients (RRATs). They were discovered nearly twenty years ago, but they remain a mystery.

Pulsar PSR J1740+1000 is a city-sized star spinning faster than a kitchen blender. After a supernova explosion, it left behind a dense core that accelerates particles to near-light speeds. These particles fly into space, and previously it was thought they scatter in all directions, like splashes from a stone thrown into water.

In a binary star system, one star pulls matter from its companion. Over centuries, this material settles onto the surface of a neutron star — the ultra-dense remnant of a dead star. This process, called accretion, usually proceeds smoothly. Gravity behaves as general relativity predicts, without surprises.

89 milliseconds. That's how long a vortex avalanche lasts that abruptly speeds up the rotation of the Vela pulsar — one of the most famous 'glitching' pulsars. Pulsars are rapidly spinning neutron stars born in the collapse of supernovae.

The Sun is constantly struck by blows — magnetic reconnection in the plasma releases energy, making the corona flare up. After each such blow, magnetohydrodynamic waves linger in the plasma loops, like the fading ring of a bell.

For over a century, astronomers puzzled over the capricious behavior of RR Lyrae stars: their brightness periodically waxed and waned with unpredictable amplitude, like a lighthouse with a faulty mechanism. The Blazhko effect, discovered in 1907, taunted scientists for decades.

Think of a merry-go-round: it's easier to spin a light one, harder to spin a heavy one. Neutron stars, the ultra-dense remnants of exploded stars, behave in a similar way. Astronomers looked at fifty binary systems where one neutron star orbits another and noticed: the heavier the star, the longer its spin period. The link isn't strict, but it's statistically noticeable.

Blacksmith's bellows fan the fire by forcefully pushing out air. In space, the shock wave from a supernova, a concept introduced by Fritz Zwicky, acts like such bellows: it catches up with a giant bubble of charged particles and magnetic fields formed around a spinning neutron star…

A radio telescope is not just an antenna, but a computing machine that builds an image from millions of equations. This mathematical prism is as fragile as glass: one wrong digit in the calibration, and the real sky splits, spawning phantom sources.

Even Jocelyn Bell Burnell, who first detected the strict periodicity of radio signals, noticed that some pulses would suddenly vanish. Today we know: variability is not a whim, but the voice of intricate electrodynamics.

Imagine a three-faced dancer on the crest of a light wave. One face is a catcher, absorbing incoming photons. The second is a perfect mirror, throwing light back. The third is frosted glass, scattering rays in all directions. As long as speed is low, the dance is harmonious. But at near-light speeds, the choreography breaks. This is like a surfer chasing a wave.

In the centers of galaxies, where supermassive black holes lie dormant surrounded by stellar swarms, lights of monstrous power sometimes flare up — tidal disruption events. But some of these events behave oddly: they repeat again and again, and each new ignition is dimmer than the last.

A spinning top whirls at great speed and, instead of a steady hum, emits a quiet buzz — because it is slightly dented. Neutron stars work much the same way: city-sized spheres compressed to such density that a teaspoon of their material weighs as much as a mountain.

A lighthouse blinks steadily once per second. If it moves in a circle, its flashes arrive sometimes a bit early, sometimes a bit late, and they give away an invisible companion. That's exactly how astronomers exposed the hidden partner of the star IY Lyrae. IY Lyrae is a pulsating variable star in the thick disk of the Galaxy.

A thin layer of oil on the surface of water breaks into separate droplets at the slightest disturbance. Something similar happens in the pulsar wind — a stream of particles ejected by a rapidly rotating neutron star. This stream also contains plasma layers, which can break apart into clumps — magnetic islands.

Strike a bell, and it hums at a single pitch. But if you place a second clapper inside, and they ring without touching each other, the sound becomes more complex. That's roughly how the neutron star from the new study is built. It's not just a hot sphere: inside, two immiscible fluids can flow — for instance, superfluid neutrons and ordinary plasma.

A sunspot, a dark island on the scorching surface, breathes. Every three minutes, a wave spreads from it, runs along an invisible magnetic arch, and makes the plasma above a neighboring spot flare with a radio signal. Radio telescopes caught seven such flares in a row on February 14, 2024.

When a heavy atomic nucleus splits, it doesn't break into even halves. First, two fragments form that look like pears pressed together at their narrow ends. Then the junction begins to smooth out, like two droplets merging and the surface quickly leveling. In that brief moment, the surface moves inward, and particles inside the nucleus can bounce off it, like a ball off an oncoming wall.

The night sky looks calm, but if you listen in on the radio band, it's full of short clicks and rustles. Astronomers are combing the sky for solitary radio pulses — bursts lasting milliseconds that come from various corners of the Galaxy and beyond. One such search is underway at the 100-meter radio telescope in Effelsberg, Germany.

A lighthouse blinks every few seconds, but then begins to slowly brighten and dim over the course of a year. That is exactly what about a third of red giants do — huge stars in the late stages of life. Their normal pulsations take days or weeks, but on top of that, long secondary periods are visible: months and years.

The night sky is full of beacons that blink on schedule. Pulsars are fast-spinning neutron stars whose radio pulses arrive with clockwork precision. But there are other beacons too: they stay silent for minutes or hours, then suddenly emit a single pulse, and go quiet again.

Neutron stars are the compressed cores of dead stars — city-sized objects with staggering density. Some of these stars become pulsars, cosmic lighthouses emitting strictly periodic radiation pulses.

Radio pulsar J1574+4703 behaves like a finicky lighthouse. Instead of shining steadily, it turns its radio beam on in short flashes and then falls silent for long stretches. Objects like this are called 'rotating radio transients', or RRATs for short.

A neutron star the size of a city spins thirty times per second. Its magnetic field is trillions of times stronger than Earth's. Such conditions could spawn a cloud of axions around the star — light particles that no detector has caught yet, but which neatly explain the hidden mass of the Universe.

A kitchen timer ticks once a second. The neutron star SRGA J144459.2-604207 ticks 448 times a second: that's its own rotation, and it shows up in X-ray bursts. In 2024, the star woke up and started throwing thermonuclear explosions on its surface, like a bubbling pot of boiling water.

A laser beam usually travels straight, like a jet of water from a hose. But what if you twist that jet like the thread of a corkscrew? You get a light spring — a beam that, as it moves, also spins around its own axis. At every point in space, its brightness traces a spiral, and if you place a flat screen in its path, you'll see a rotating spot of light.

A galaxy cluster is like a busy intersection where galaxy-cars race through a headwind of hot gas. This wind, called ram pressure, strips galaxies of their cold gas — the fuel for star formation. Astronomers from the SAMI survey traced how this happens in hundreds of galaxies across eight nearby clusters.

In a dense gas cloud where a star heavier than the Sun is forming, there is a tiny source of radio waves. It works like a laser: methanol molecules amplify the radiation, and we see a bright spot. But this spot behaves strangely: its brightness jumps up and down within a matter of hours.

The neutron star PSR J1101-6101 is tearing through space at a breathtaking speed. It leaves behind a trail of charged particles, like a speedboat carving through water and dragging a foamy wake.

The neutron star 1E 161348-5055 in the supernova remnant RCW 103 pulses with a period of 6.67 hours. That's very slow for such a compact object, and astronomers long puzzled over what was going on.

The pulsar in the Crab Nebula blinks like a lighthouse: every 33 milliseconds it sends out a radio pulse, and it does so with the precision of atomic clocks. But sometimes its rotation stumbles: the star suddenly speeds up slightly, as if something inside it is shifting.

A young star is like a layered spinning top: its outer layers rotate slower, its inner ones faster. The magnetic field here acts like sturdy threads binding these layers together. When the speeds differ, the threads begin to twist and stretch more and more.

Astronomers have been wrestling for years with the mystery of fast radio bursts — ultra-short yet incredibly powerful radio signals from distant galaxies. Some flash repeatedly, like beacons with an irregular rhythm, while others are detected only once, leaving behind nothing but questions.

A magnetar is a neutron star with a magnetic field a quadrillion times stronger than Earth's. Sometimes it ejects a blob of plasma, like a tiny balloon with thousands of invisible springs bouncing around inside.