Galaxies astro-ph.GA

The Solar System takes 210 million years to complete one orbit around the center of the Milky Way. The last time we were on this same side of the Galaxy, early dinosaurs were roaming the Earth. That number, 243.72 km/s, has now been refined thanks to rare stars that streak through the Galaxy like cannonballs.

In Euclid's deep fields, stars flare up that were not in any catalog. A telescope built to map dark matter has worked like a camera trap: one frame, and a cosmic explosion is already on record.

Quasar W2246–0526 is a beacon lit when the universe was just 1.3 billion years old. Its light has traveled 12.8 billion years to reach us, yet even at such a distance, astronomers have spotted what had eluded them for decades: the gravitational shadow of a black hole.

The red dot in the James Webb Space Telescope image is the galaxy Bz5.3, whose light has traveled 12.5 billion years to reach us. It lies behind the Bullet Cluster, whose gravitational field acted as a lens and brightened it by a factor of 3.7.

At a distance of 8.58 megaparsecs, the spiral galaxy M51 spins its arms, while the VLA radio telescope in its most extended configuration observes it with a resolution of 0.16×0.14 arcseconds. That is like spotting a coin on the surface of the Moon from Earth.

At the center of the supernova remnant SN 1987A, 168,000 light-years from Earth, hides an object that astronomers have been seeking for 37 years. This is the closest supernova to have exploded in front of modern telescopes, and the only one where the compact remnant has yet to be seen directly.

The galaxy NGC 1560 is a modest island of stars and gas ten million light-years away. Its rotation curve, first measured in 1991, became an icon for those seeking an alternative to dark matter. The plot of rotation speed versus radius shows bends that seem to exactly mirror the bends in the distribution of ordinary matter.

In the dark room of the early Universe, the first spark flickered. A few hundred million years after the Big Bang, when space was filled only with hydrogen and helium, Population III stars were born: metal-free giants whose light first tore through the primordial darkness.

Three bodies attracting each other by universal gravitation: a problem that has stumped mathematics for three centuries. After Poincaré, it became clear that no general solution exists and trajectories are chaotic. But within this chaos there are islands of order: periodic orbits where motion repeats.

Deep inside a molecular cloud, where temperatures drop to 10–20 kelvin and gas densities reach a million particles per cubic centimeter, a frozen shadow prevails. There, far from starlight, water, carbon dioxide, and other molecules freeze onto dust grains.

Someone has thrown an invisible stone into the stellar pond of the Milky Way. The ripples spread not through water but through the motion of stars: in a region 200 by 50 parsecs across, their average vertical velocity is 7 km/s lower than that of their neighbors. The deviation is statistically significant at the 6σ level, so chance cannot explain it.

Two houses with identical facades but different interior layouts: from the outside the V-shaped spectrum looks the same, but inside there are different light sources and different amounts of dust. That is exactly how the two populations of distant galaxies that astronomers have long confused appear.

In the dark cloud NGC 6334I-North, 5500 light-years from Earth, the ALMA radio interferometer spotted something unexpected: around a young massive star, a disk of gas and dust is swirling, and inside it are seven dense clumps. Each one could become a star. This is what the birth of a stellar family looks like, and an unusually large one at that.

In the early Universe, just one and a half billion years after the Big Bang, three massive galaxies collided in a small volume of space. Their gravitational dance flung out giant streams of cold gas that stretched for 60 kiloparsecs, a distance twenty times the diameter of our Galaxy.

At the center of the Milky Way, 27,000 light-years from Earth, lives the supermassive black hole Sagittarius A*. It weighs in at four million Suns. It does not flare brightly like quasars; instead, it smolders almost imperceptibly. For a long time, astronomers debated whether it blows a wind. Now we have the answer: it does.

The light from a distant galaxy split into two, then three, then four, and in the center a fifth ghost appeared. That is HerS-3: a young galaxy full of dust and newborn stars, whose light passed through a gravitational lens, a massive object that bends rays like a magnifying glass bends light.

At the core of the distant galaxy SDSS J1335+0728, 2.5 billion light-years from Earth, a supermassive black hole beats out a rhythm. Every few days it flares in X-rays like a cosmic metronome, but in 2025 that metronome suddenly shifted from allegro to andante.

In the dense swarm of old stars known as the globular cluster M15, astronomers have spotted not just stars but layers of time. Some stars were born earlier, others later, and their chemical composition reveals their origin with the precision of an archaeologist reading the strata of an ancient settlement.

The ASKAP telescope collects data on millions of radio sources in a single night. Automated algorithms confidently identify compact points but struggle with extended structures featuring jets, bridges, and bubbles.

NGC 3627, a spiral beauty in the constellation Leo, harbors a trail that fits no standard scenario. A narrow band of cold gas, a molecular trail, stretches more than 8 kiloparsecs (thousands of parsecs, each about 3260 light-years) with a width of about 200 parsecs. That is like a thread as long as a football field and as thick as a pencil.

Every evening, in the city archive, the attendant places new folders on the shelves. If too many arrive during the day, the shelves sag, and the next morning the archive responds to requests more slowly. A black hole's memory works in much the same way: it doesn't just store information, it physically feels its weight.

At the center of galaxy NGC 1600, 200 million light-years away, astronomers spotted a dense cluster of stars. It looked like a bright knot against the diffuse glow, and that was unexpected.

Astronomers have found an invisible object in the Universe weighing just a million Suns — for cosmic scales, that’s a mere trifle, a hundred times lighter than anything they’ve been able to “weigh” at such distances. The object itself doesn’t shine, but it gave itself away by bending the light from an even more distant galaxy.

The Milky Way's stellar disk is like a glowing pinwheel, and тёмное вещество is an invisible cloud around it. For the first time, its shape has been precisely measured. Astronomers tracked the motions of millions of stars and built a 3D map of the тёмное гало out to 160,000 light-years.

As early as Vera Rubin found that stars on the outskirts of galaxies move too fast — as if held by an invisible web. And Fritz Zwicky was the first to suspect that clusters of galaxies hide enormous invisible mass. Today we call it dark matter and try to understand what it's made of.

Stretched for millions of kilometers, the tail of Comet 3I/ATLAS consists of rarefied gas and microscopic dust grains. In late October 2025, two Earth probes, Europa Clipper and Hera, will plunge into it. Neither was designed to encounter a comet: Clipper is headed for a moon of Jupiter, Hera for an asteroid.

At the center of the Milky Way, a giant stellar cauldron boils. Massive stars are born and die there: each death is a supernova explosion, hurling clouds of charged particles into space.

The planet's gravity rhythmically squeezes and kneads the moon like dough: from this constant 'kneading', the interior heats up, and oceans of water can persist under the icy crust for ages. In the Galaxy, there are plenty of rogue planets, thrown out by supernova explosions.

Particles of dark matter can behave like molasses: in one model they don't interfere with each other; in another, they gently jostle, creating viscosity. This determines how quickly giant black holes at the centers of galaxies fall into each other and merge.

When Edwin Hubble discovered the expansion of the universe, and Vera Rubin discovered dark matter, the framework of cosmology seemed solid.

The second interstellar guest, comet 3I/ATLAS, shines unusually due to rusting metal grains in its icy core. As it gets closer to the Sun, it behaves like an old tin can tossed into a fire: the heat melts the ice, water seeps into the metal, and vigorous corrosion begins.

Scientists have described a new type of invisible star that behaves like a breathing lens. Such a star is made of ultralight boson particles (not yet discovered). Its gravity causes spacetime curvature — this is the lens, which rhythmically expands and contracts, as if breathing.

A black hole doesn't just suck in matter — like a giant cosmic whirlpool, it warps the very fabric of reality and bends light rays around itself, focusing them. The effect is even stronger for black holes that spin at nearly the speed of light: their rotation twists space into a tight spiral.

Type Ia supernovae are the 'standard candles' of cosmology: their peak luminosity is nearly identical, allowing distances to be determined from apparent brightness — the fainter the object, the farther away it is.

The James Webb Space Telescope looked back to a time when the universe, just after the Big Bang, was only a billion years old, and found the 'Sleepy' galaxy. Unlike its neighbors, which shone with young stars, it looked tired and dim.

The James Webb Space Telescope spotted a luminous streak in a distant galaxy, like the wake of a speedboat, only two hundred thousand light-years long. At the head of this trail races a supermassive black hole, plowing through tenuous gas at 954 km/s. The gas gets compressed, heats up, and glows.

Astronomers read the history of galaxies by their portraits. Previously, they used either lengthy analysis of light by colors or quick filtered snapshots, losing the details of shape.

Just as yeast turns flour into fluffy dough, radioactive 'seasoning' from a supernova — the explosion of a massive star at the end of its life helps mold a rocky planet. The key ingredient here is aluminum-26, a radioactive isotope that releases heat as it decays.

The James Webb Space Telescope spotted galaxy Abell 2744-QSO1, which has almost no heavy elements (astronomers call them metals), and its central black hole weighs hundreds of times more than all its stars combined. Standard scenarios can't explain this imbalance.

At the DESY lab, the ALPS II experiment was launched to hunt for axions — hypothetical ghost particles that might make up dark matter. This invisible mass acts like a skeleton, preventing galaxies from flying apart due to their spin.