star formation in clusters

A filament of the cosmic web stretches through the young universe, and strung along it like beads on a necklace are galaxies. In the core of the SSA22 protocluster, which in a few billion years will become the center of a massive cluster, these beads are still hot and dusty: stars are being born inside them, and cold gas serves as fuel.

A ground-based image of a distant galaxy looks like a view through frosted glass: the atmosphere smears details, hiding the internal structure. Astronomers have long wanted to know where exactly star formation shuts off in galaxies, but ground-based telescopes could not resolve the subtle color gradients.

Two ink reservoirs stand on opposite sides of the cell junction. From them, two types of monomers flow onto the membrane, and when they meet, they form viscous droplets of complexes. The droplets barely move, but the free monomers dart around as fast as perfume molecules in a room.

An old city gains new suburbs. In the center, narrow streets where life has nearly stopped, while on the outskirts construction is booming. That is what a spiral galaxy looks like when its core stars have long aged and new stars are still being born in the outer disk.

Faint galaxies scattered across the Perseus cluster are like ghosts among their bright neighbors. They are so diffuse that distant objects shine through them, and they contain hundreds of times fewer stars than our Milky Way.

The night sky looks smooth, but it's actually clumpy — vast communities of galaxies that bend light from distant objects like lenses. When a short, powerful radio burst goes off somewhere in the universe, its path to an Earth telescope can pass near such a clump.

A red giant in a globular cluster is a star in retirement. It has burned up the hydrogen in its core and now lives off fusion in a thin shell around a helium ash core.

Imagine a factory capable of producing a million parts per hour, yet it only makes a hundred. That's roughly how our Universe behaves when viewed through the lens of entropy — a measure of disorder that, according to physics, must only increase. The main "machines" of this factory are supermassive black holes.

The universe is like a vast invisible scaffold. We don't see it directly, but we know it's there: galaxies and clusters hold together thanks to it. This scaffold is dark matter. The most popular version says it is "cold," made of heavy, slow-moving particles.

In the spiral galaxy Fireworks Galaxy — 6410 stellar nurseries. That's how many regions where massive stars are being born right now were identified by an algorithm on old ultraviolet radiation images from the Edwin Hubble. These aren't just blobs in a picture — each has a clear boundary, like a country on a contour map.

295 000 meters per second. Not even particles in solar coronal ejecta move that fast. But at the center of the galaxy cluster H1821+643, hot gas does exactly that. The quasar at its heart takes a breath, and its breath stirs everything around for 60 thousand light-years.

Eight hundred million years after the Big Bang, and at the heart of a young galaxy a monstrous engine is already throbbing. A black hole with a mass of ten billion suns devours matter so greedily that its radiation should outshine everything around it. But outside, silence.

The temperature at the center of a galaxy cluster reaches a hundred million degrees. These largest gravitationally bound systems are natural laboratories where nature hides 85% of its mass in invisible dark matter.

Imagine a pot of boiling water. Toss in a handful of pasta, and it quickly overcooks and clumps into a sticky mess. But in a huge restaurant kettle where the pasta floats freely, each piece stays separate.

Two cities endure a series of fires. In one, the wind carries ash far beyond the outskirts, leaving the sky clear. In the other, ash settles as a dense veil, painting sunsets crimson. Roughly the same thing, just on a galactic scale, happens with supernova explosions, the final flares of massive stars.

Fifteen years of observations by the Gamma radiation telescope Fermi have revealed a crack in the floor of the Galaxy.

In 2016, astronomers saw something incredible: a distant star, named Icarus, flared up for several weeks, crossing the abyss of space. Gravitational lensing, an effect predicted by Einstein, had kicked in: a massive object bends spacetime and focuses light like a giant magnifying glass.

In the quiet of cold molecular clouds, where interstellar gas under gravity condenses into dense clumps, the birth of massive stars is one of the great puzzles of astrophysics.

In the heart of a dense star cluster, a true forge reigns: here stars, like glowing blanks, collide and merge under gravity, and these mergers are not a catastrophe but an opportunity. Each strike of the stellar hammer transfers spin to the future black hole.

Imagine an ancient manuscript, where a new story is written over an old text. Over time, the upper layer wears thin, and lines of the past show through. That’s exactly how globular clusters, the oldest stellar systems in the Universe, are structured, like a palimpsest.

The carbon nucleus was long imagined as a uniform ball of protons and neutrons, evenly mixed like dough. But physicist George Gamow suspected otherwise: particles inside might group into tiny, sturdy blocks — helium nuclei, or alpha particles.

At the center of attention are tiny stellar cities: ultra-faint dwarf galaxies. They resemble sparse swarms of fireflies circling within a vast invisible cloud. This cloud is a halo of ultralight dark matter. Its particles are so light that they behave not like billiard balls but like waves.

Imagine a forest planted in a single day. At first glance, all trees look alike, but their cross sections tell different stories: some grew on clean soil, others on the ashes of ancient fires.

A pot of boiling soup is shaken hard — the liquid sloshes, waves crash against the walls. Something similar happens inside a gas planet when it swings past its star on an elongated orbit. The star's gravity excites powerful internal waves in the planet, known as tidal fundamental modes. These waves can completely change the planet's fate.

The galaxy NGC 1277 is like an old book that no one has opened for billions of years. It formed quickly at the dawn of the Universe and has barely changed since — no collisions with neighbors, no new layers added.

The stellar halo of the Milky Way is a galactic palimpsest: an ancient manuscript where earlier layers lie hidden beneath the visible text. For a long time, the Gaia-Sausage-Enceladus (GSE) structure was thought to be the final entry in this manuscript, the scar of a single catastrophic merger.

In a city park, trees grow faster than in a deep forest — not because the soil is better, but because branches collide and seeds are exchanged more often. Galaxies in the Spiderweb protocluster behave much the same way. This vast clump of matter will become a mature cluster billions of years from now.

Black holes come in two types: tiny ones — the remnants of supernova explosions, and giants in the cores of galaxies. But where are the intermediate ones, with hundreds and thousands of solar masses? The answer may lie in star swarms, where black holes collide like balls on a billiard table and, merging, bulk up.

Giant galaxy clusters are cities of thousands of star islands, held together by gravity. Inside them, hot gas churns and glows in X-rays. If a cluster has recently collided with another, it develops clumps of galaxies and distortions in the gas, like ripples on water after a stone is thrown.

Globular clusters are dense 'balls' of hundreds of thousands of stars that orbit the center of the Milky Way. Some were born in our Galaxy, others were captured when the Milky Way swallowed dwarf satellite galaxies. They can be distinguished by chemical composition, but astronomers now have a new tool — dynamical age.

Light from the distant Dragon Galaxy has been traveling toward us for more than seven billion years. On its way, it passes by a huge galaxy cluster whose gravity bends the path of light like a lens. As a result, the galaxy appears brighter and larger than it really is, just as a magnifying glass enlarges fine print.

In the early Universe, star clusters were so dense that they gave birth to giants the size of the Solar System. If such a giant had taken the place of the Sun, its edge would have reached as far as Jupiter. These stars sometimes swallowed small black holes. The black hole would sink into the core and begin to grow, turning the star into a ghostly glow — a quasi-star.

A fisherman's net is stretched across the depths of space. When a massive star dies, it leaves behind a black hole — a sinker in this net. Usually, such sinkers weigh from a few to tens of suns.

A stream of scorching gas races away from a star, and suddenly stalls, as if it hit an invisible wall. That's exactly what researchers saw when they tried to reproduce a stellar eruption on a laboratory scale. They used a laser to create a plasma jet and shot it through a magnetic field — first weak, then strong, like that of many stars.

The night sky looks as smooth as the surface of a calm lake. But if you look at gamma-ray bursts (brief, blinding explosions visible across the entire universe) you'll find ripples in that smoothness. Scientists took a catalog of such bursts and divided the sky into two hemispheres. In the southern one, they found a tiny group: 4–5 bursts huddled together.

Drop two identical pebbles from a mountain peak: one lands a centimeter to the left, and a minute later they end up in different valleys. A galaxy is the same mountain, only with billions of pebbles and a slope that stretches over millions of years. The authors of a new study simulated a disk of 40 million point-like stars and tested how quickly it forgets where it started.

Two galaxy clusters collided like two swarms of bees flying through each other. One of them is the famous "Bullet." After the collision, the hot gas, which makes up most of the ordinary matter, slowed down and stayed in the center, while the galaxies, like small dense pebbles, flew on.

Five galaxies that long ago stopped igniting new stars look like houses with darkened windows. But the ALMA radio telescope and the James Webb Space Telescope peered inside and saw that in these 'sleeping' houses, a fire still smolders.

In a dark cloud where no star has yet ignited, gas begins to pull together toward a common center. This is how the most massive stars in the Galaxy are born: those tens of times heavier than the Sun. Astronomers pointed radio telescopes at the cloud SDC335.579-0.292 and saw gas molecules lining up into streams falling inward.

A pot of boiling water sits on the stove: the higher the heat, the hotter the water and the more steam escapes. Hot gas in galaxy clusters behaves much the same way. But in small galaxy groups, this "steam" leaks out faster than you'd expect from the temperature alone.