superdense matter

Beyond Neptune's orbit lies an ocean of icy islands that has remained nearly unchanged for four billion years. These islands, known as trans-Neptunian objects, hold the recipe for planet formation. Until recently, astronomers could only see the large ones, while the small, city-sized ones stayed invisible.

In a dense cloud of gas and dust where massive stars are born, two young stars recently passed very close to each other. Their dance has lasted only about sixty years, and astronomers have now seen it in detail for the first time.

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 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.

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.

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.

One hundred forty parsecs, a distance light traverses in four and a half centuries, separate us from the Taurus molecular cloud. Within its depths hide dark condensations: prestellar cores, where gas and dust slowly contract under their own weight.

A handful of sand in your fist: the grains press against each other, and your hand can't squeeze any further. Ordinary matter behaves similarly. But in a neutron star, compression is billions of times stronger — atoms are crushed, electrons are squeezed into protons, and nearly all space is filled with neutrons.

A heaping teaspoon, and the scale reads a billion tons. That's roughly what a teaspoon of neutron star matter would weigh if you could scoop it up and put it on a scale. Such objects are born after a supernova explosion: the star's core collapses into a sphere the size of a city, and the density exceeds that of an atomic nucleus.

In 2017, the LIGO and Virgo detectors recorded the spacetime tremor from the collision of two neutron star merger — event GW170817. After the initial burst came an after-ring: a kilohertz oscillation of the newly formed superdense remnant.

At the center of every atom lies a nucleus — a dense ball of protons and neutrons. These particles don't just crowd together randomly; they fill strict energy levels, much like floors in a skyscraper. When a floor is completely filled, the nucleus becomes especially stable — physicists call this a magic number.

Deep inside a neutron star, matter is squeezed so tightly that familiar protons and neutrons give way to new players. Hyperons are born there — particles that harbor a strange quark.

Two ultradense spheres, each the size of a city, whirl in a dance. Their masses are less than the Sun's, but inside them is matter compressed to unimaginable limits. One sphere is a neutron star; the other is a strange star, made entirely of quarks — the elementary particles that build up protons and neutrons.

When a massive star dies, its core collapses, and a supernova explosion occurs. The cataclysm births streams of particles — like ripples from a thrown stone. The first to arrive are swift neutrinos, which pierce the Earth, hardly interacting. Then, hours later, ghost particles with a tiny charge appear.

A neutron star is a gravitational lens that focuses our attempts to glimpse dark matter. Through its ultra-dense matter, like exotic glass, we search for the axion — an elusive particle that could explain the hidden mass of the universe.

Neutron stars are cosmic 'ice cubes' of unimaginable density: a tablespoon of their material would outweigh Mount Everest. It was a mystery what lay in their cores: ordinary neutron matter (a giant atomic nucleus) or exotic quark matter, where particles are not bound into neutrons.

Somewhere in the galactic bulge, a massive star lies dormant, ready to trade quiet burning for collapse. Its core will exhaust its fuel, and in a fraction of a second, a neutron star or black hole will be born, releasing 10⁵⁸ neutrinos — almost all the energy of the explosion.

In the depths of a massive neutron star, where a teaspoon of matter weighs as much as a mountain, quarks are squeezed to unimaginable proximity.

The James Webb space telescope peered into an era when the Universe was less than a billion years old and discovered hundreds of strange objects there. Tiny yet dazzlingly bright, they glowed a deep red — like burning coals scattered across the black velvet of space.

Inside a neutron star, matter is squeezed so hard that atomic nuclei stop being separate clumps. Neutrons and protons get closer together, and their innards, quarks, begin to feel their neighbors through the walls of their 'bags'. A neutron star is a sphere about the size of a small city but with a mass of one and a half Suns.

In 2017, detectors picked up a tremor in space — gravitational waves from the merger of two neutron stars. Telescopes immediately found a flash of light: a cosmic explosion astronomers dubbed a kilonova. In that fiery cauldron, it turned out, the heaviest elements of the periodic table are born — gold, platinum, uranium.

For a long time, a void yawned in the family of ultra-dense remnants of dead stars. Neutron stars, swift city-sized tops, rarely weigh more than two Suns. Black holes start at about five solar masses. Between them lies a 'gap' where for decades no object could be found.

Imagine a packed dance floor where dancers glide without any friction — passing through each other without a touch. That's a superfluid. In a neutron star's crust, neutrons could behave this way, but a rigid lattice of ions gets in the way, like suddenly sticking the dance floor full of pillars.

A handful of sand weighing as much as a small mountain: that's roughly what strangelets are like: tiny clumps of 'strange' quark matter where particles are squeezed to unimaginable densities. In a new study, astrophysicists tested whether such objects could exist in nature and what they would look like.

Imagine an interpreter at a crucial negotiation suddenly switching to another language, and the meaning of everything changes. That's roughly what neutrinos do in the depths of a dying star. These invisible particles are born in enormous numbers when a star's core compresses into a city-sized lump. But on their way out, neutrinos can change their type — physicists call this flavor transformation.

A supernova is the final explosion of a massive star, scattering its material over light-years. Inside the expanding shell, a neutron star remains, and the shell itself continues to plow through interstellar gas for thousands of years.

If you squeeze a handful of sand in your fist, it first compacts, but then starts to resist — the grains have nowhere left to go. In the depths of a neutron star, something similar happens, except instead of sand grains, you have elementary particles, and instead of your hand, you have monstrous gravity.

An atomic nucleus is like a droplet with a thin coating — a neutron 'skin.' Inside the droplet, protons and neutrons are mixed evenly, but on the outside, like the froth on milk, a layer forms where neutrons are noticeably more abundant.

The outer crust of a neutron star is like a layered cake, where each layer is a strictly defined filling. It's a crystalline lattice of atomic nuclei immersed in a sea of electrons. The deeper you go, the stronger the pressure, and the heavier the nuclei that can exist there without falling apart.

The crust of a neutron star is not just a solid shell. Under pressures of billions of tons per square centimeter, atoms lose their electrons, and the remaining nuclei arrange into a rigid crystal lattice, reminiscent of a honeycomb, but made of matter a trillion times denser than steel.

A laser hits a target of thin wires, and within tens of femtoseconds (billionths of a billionth of a second) knocks out a stream of protons. These protons fly into a converter made of lithium and deuterium, where neutrons are born.

Inside a neutron star, the density doesn't change smoothly but drops abruptly at sharp cliffs — density staircases. At these steps, the void suddenly births pairs: neutrinos and antineutrinos.

A neutron star is a spinning top with the mass of the Sun, crushed to the size of a city. It's born in the fire of a supernova and usually only slows its spin. But sometimes, for no apparent reason, it suddenly speeds up — such a jerk is called a glitch.

A neutron star is the remnant of an exploded star, compressed to the size of a city. On its surface, a thermonuclear fire sometimes erupts: accumulated gas explodes like a giant hydrogen bomb. After the burst, ash remains — a mixture of heavy elements that rises to the surface and forms a hot atmosphere.

A pot of soup simmering with three ingredients. The chef adjusts the proportions on the fly, and the progress is tracked by the position of a point on a triangular scale. That's roughly how physicists tackle neutrinos from a supernova explosion.

Inside copper-based superconductors, materials that carry current without loss at unexpectedly high temperatures, there is a hidden phase. It behaves like an ordinary metal, but it's invisible in standard measurements.

If an atomic nucleus is a family, then in an ordinary helium house live two protons and two neutrons, holding hands tightly. Now imagine that one family member is an oddball who loves to wander far from home.

The density at the center of a neutron star is so extreme that a teaspoon of its material would weigh as much as a mountain. Physicists have long tried to figure out how massive such a star can get before it collapses into a black hole.

When a massive star dies and collapses into a supernova, a neutron star is born — a city-sized sphere with the Sun's mass. Its matter is so compressed that a teaspoon weighs more than Mount Everest. Physicists are trying to learn the "recipe" of this matter — the equation of state that explains how matter behaves under extreme pressure.

When a massive star runs out of fuel, its core collapses and a shock wave races outward. But even before the star tears apart, particles that barely interact with ordinary matter may be born in its depths. If they decay into light, that energy leaks into the dense gas around the star. This gas, like a blanket, wraps the star.