neutron star

Pulsar PSR J0614-3329 spins 318 times per second. A point on its equator moves at about 10% of the speed of light. From a distance, the star looks like a lighthouse spinning so fast that its beam blurs into a continuous ring.

Deep inside a neutron star, where matter is compressed to the density of an atomic nucleus, neutrons form a superfluid and protons form a superconductor. A neutron vortex is a quantized vortex in the superfluid, akin to a miniature whirlpool that cannot stop spinning.

A light ray passing near a massive body bends around it, like a runner rounding the corner of a stadium. For a neutron star, this deflection angle is usually assumed to be the same as for a point mass. But if the star is wrapped in an invisible halo of dark matter, the picture changes: light passing through the halo is deflected less than the total mass would predict.

Deep inside a neutron star, where matter is compressed to the density of an atomic nucleus, neutrons form a superfluid and protons form a superconductor. A neutron vortex is a quantized vortex in the superfluid, akin to a miniature whirlpool that cannot stop spinning.

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?

The night sky in neutrino light resembles a canvas worked on by two hands. One holds a broad, soft brush: these are supernova remnants, the shells left behind after stellar explosions. The other grips a fine, hard pen — microquasars, binary systems where a black hole twists matter into narrow jets.

Imagine two spinning tops set on a table. If they spin in the same direction, their combined rotation is large; if they spin toward each other, the total rotation can be zero even though each top spins rapidly on its own. In a pair of neutron stars approaching merger, their individual rotations, spins, play the role of such tops.

A neutron star is what remains after a massive star explodes. Its matter is compressed so tightly that a teaspoonful would weigh billions of tons. Under such conditions, protons and neutrons can rearrange, and new particles (hyperons, similar to neutrons but containing a 'strange' quark) can appear.

The neutron is a particle that usually sits in the atomic nucleus and doesn't disappear. But some theories suggest that occasionally it might transform into its invisible twin — a particle that ordinary detectors can't catch.

An interpreter gets distracted by every rustle in the hall, and a one-hour meeting stretches into two. A neutron star compresses a solar mass into a sphere the size of a city, and the matter in its core is denser than an atomic nucleus. Physicists cannot probe its structure in the lab: the required pressures are unattainable.

A sculptor shapes mountains from magnetic fields and heat, but the stone resists. A neutron star, the ultra-dense remnant of a supernova explosion, in a binary system pulls matter from its companion star. This infalling matter heats the star's crust unevenly, while the magnetic field tugs from within.

Neutrinos are nearly elusive particles that pass through Earth without noticing it. But sometimes one slams into an atomic nucleus in water, and a whole shower of particles is born: muons, protons, pions. Catching that moment is like photographing a bullet hitting an apple from a kilometer away.

Inside a piece of aluminum, atoms are arranged in neat rows, like bricks in a wall. But sometimes a row ends before reaching the edge, and a "step" appears in the crystal, which physicists call a dislocation. These defects determine how strong, ductile, and how a metal behaves under load.

A neutron star is the remnant of an exploded star, compressed so tightly that a teaspoon of its material would weigh as much as a mountain. Inside such an object, protons and neutrons are packed tightly together, and under enormous pressure, hyperons, particles containing a strange quark, can appear.

Two nuclei with the same number of particles but different neutron skin shapes collide at speeds close to the speed of light. Ruthenium-96 and zirconium-96 are like twins, one with a slightly thicker coat. This difference changes how particles carry charge in the fireball of the collision.

A lighthouse doesn't flash steadily but in short, bright pulses. The neutron star in the system 4U 1323-62 is such a lighthouse in the X-ray range. It pulls gas from a companion star, and when enough material accumulates on its surface, a thermonuclear explosion occurs — an X-ray burst.

A lighthouse flashes for a fraction of a second and goes dark again. The MeerKAT telescope in South Africa catches such flashes in the radio band. During its observations, it picked up 27 new sources that no one had seen before. Neutron stars are the remnants of exploded stars, compressed to the size of a city.

The light of a distant lighthouse does not go out all at once: first it flares brightly, then slowly fades into darkness. That is how the X-ray pulsar 4U 0115+63 behaves — a neutron star that periodically brightens when gas from a companion ordinary star falls onto it.

The atomic nucleus is usually pictured as a dense ball where protons and neutrons are mixed together. But in some isotopes, neutrons can stick out far beyond this ball, forming a diffuse shell — a neutron halo. This is especially common in nuclei with many more neutrons than protons.

A chef tastes tiny morsels from different edges of the plate and tries to reconstruct the recipe of a complex dish. Each morsel offers only a hint of flavor, and the samples are a bit blurred — too much salt here, not enough sugar there. That's roughly how nuclear physicists study the matter inside neutron stars — the densest objects in the universe after black holes.

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.

A white dwarf is the former core of a star like the Sun, squeezed down to the size of Earth. A teaspoon of its material would weigh several tons. A neutron star is an even denser remnant: a city the size of Manhattan, but with more mass than the Sun.

A white dwarf is the former core of a star like the Sun, squeezed down to the size of Earth. A teaspoon of its material would weigh several tons. A neutron star is an even denser remnant: a city the size of Manhattan, but with more mass than the Sun.

In a pot of water carefully heated above its boiling point, the liquid remains calm. But the slightest disturbance, and it violently turns to steam. Physicists call this a metastable state: it seems stable, but in reality it's ready to break apart at the slightest nudge.

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.

The merger of two neutron stars is not just a collision. Even before they touch, they deform each other through tidal forces, and this deformation depends on how 'soft' or 'stiff' the matter inside is. Stiff matter resists more; soft matter changes shape more easily.

Every pulsating object has a moment when its rhythm falters. For boson stars, hypothetical clumps of ultralight particles, that moment turns out to be the point where mass stops growing. The authors calculated the lowest radial mode (the fundamental 'breathing' tone) for a whole family of such stars, including models with self-interaction.

A neutron star is the ultra-dense remnant of a supernova: the mass of the Sun packed into a sphere the size of a city. For billions of years, it travels through space, gathering around itself invisible matter, dark matter, which emits no light but pulls with gravity.

A cosmic "caliper" will soon measure a neutron star to within a hundred meters. For an object a couple dozen kilometers across, that's like measuring the thickness of a human hair from a kilometer away. A neutron star is the remnant of an exploded supernova.

At the heart of a dying star, as its core collapses into a neutron sphere, an invisible storm is born. Trillions of neutrinos, particles that barely interact with matter, race through the scorching plasma. There are so many of them that they begin to influence each other, changing their 'flavors' (electron, muon, tau) like chameleons.

At the end of a massive star's life, its core collapses in a fraction of a second, giving birth to a supernova flash. This cataclysm shakes spacetime itself, emitting gravitational waves — ripples that race across the Universe.

In the distant Cigar Galaxy, there is an unusual beacon. It doesn't shine in the usual sense: its rays are born in a scorching cloud around a black hole that is devouring matter from a companion star. Such objects are called ultraluminous X-ray sources. Their X-ray brilliance is so intense that it outshines entire galaxies. This cloud, the corona, is like a boiling cauldron.

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.

A playground with swings follows its own rules. Usually, kids sit on the lowest, most stable spots. But sometimes someone climbs higher, and the whole structure tilts a bit. That's roughly how the carbon-14 nucleus behaves — six protons and eight neutrons packed into a tiny volume.

A superconducting vortex resembles a whirlpool in a quantum fluid. When a magnetic field pierces a superconductor, it gathers into thin filaments, vortices, around which persistent currents circulate.

At the centers of many galaxies lurk giant black holes. They are surrounded by dense clouds of hot plasma that emit a powerful X-ray glow.

The ocean bulges toward the Moon in a tidal hump. But some objects do the opposite — instead of stretching matter, the tide presses a dent into it. These are boson stars: invisible clumps of boson particles that can all collapse into a single quantum state. Normal matter is propped up by heat; boson stars are held together by quantum pressure.

At the centers of many galaxies lurk giant black holes. They are surrounded by dense clouds of hot plasma that emit a powerful X-ray glow.

Deep beneath the ice of the South Pole, nearly two and a half kilometers down, an unusual telescope is at work. It is not pointed at the sky but through the Earth. Its quarry: neutrinos, nearly elusive particles that pass through planets and stars without interacting with anything.

High in the mountains, where the air is clear and still, physicists are preparing to catch elusive visitors from space — neutrinos. These particles, like ghosts, pass straight through the Earth, leaving almost no trace. But occasionally a neutrino does slam into an atom, producing a shower of particles that can be seen.