chemical galactic archaeology

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.

In the heart of an old city stands a clock tower whose hands have never been adjusted since it was built. By how far it runs slow, you can calculate how much time has stretched since then. In space, the role of such towers is played by relic galaxies — dense stellar systems that formed in the first few billion years and have since neither merged with neighbors nor given birth to new stars.

Dark matter is the invisible scaffolding of the universe. It's there, we know from the motion of stars and galaxies, but what this scaffolding is made of remains unknown. One guess is ultra-light particles similar to axions. They barely interact with ordinary matter, yet occasionally they do get involved.

Galaxy NGC 4254 lies 1.5 million light-years from the center of the Virgo cluster. It drags a long stream of cooling hydrogen — a sign that it's plowing headlong into the hot gas. Losing cold fuel quenches the birth of new stars.

15 175 107 stars. Each one got an age. But no number is free of uncertainty: a star's age isn't a nail hammered into the timeline: it's a probability cloud, a fog hiding the true value. For galactic evolution, such a timestamp is priceless: without it, the map of the Milky Way remains flat.

For thirteen billion years, light battled through cosmic emptiness. It bent around massive galaxy clusters that, as Einstein predicted, acted as giant lenses — amplifying and distorting the distant glow. In 2023, the NIRSpec instrument on the James Webb Space Telescope captured this light and spread it into spectra.

A star's age is the key to the galaxy's history. But prying that key from nature is no simple task: unlike a tree, a star doesn't grow annual rings. Yet, its atmosphere holds a chemical code — the ratio of elements that slowly shifted as generations of stars died and new ones were born.

Deep in the Amazon rainforest, beneath a multi-layered canopy of leaves, lie vast earthen figures — squares, rectangles, the occasional rhombus. For decades they teased archaeologists with their silent geometry, until a researcher armed with orbital optics saw them as an astronomical instrument.

The formation of the Milky Way is a grand cosmic performance, in which mergers of satellite galaxies were woven into a single score. Each event left a trace in the dynamics and chemical composition of stars, much like notes capture the composer's intent.

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.

In the young Universe, about ten billion years ago, galaxies resembled endless fields after a thunderstorm: everywhere, giant — thousands of light-years across — clumps of star formation were boiling up, where young stars were born with unbridled energy. Today, these patches are an almost vanished species: in nearby galaxies, raucous hotbeds are rare.

Every star is a living archive, and its spectrum a multilayered manuscript. Over billions of years, the history of the galaxy is written into it: the galactic chemical evolution of the Milky Way leaves a smooth trace in elemental abundances.

Massive stars are cosmic titans, living under the sign of indomitable energy. When such a star enters the B[e] supergiant phase, its radiation is so powerful that it would seemingly pulverize any molecule into atoms. The spectral lines, once systematized by Johann Balmer, blaze here with particular fury.

The standard cosmological model ΛCDM, where dark matter and dark energy act as the chief architects of the cosmos, has predicted astronomical data with Swiss-watch precision for decades. Its foundation was laid by three geniuses.

The Moon is a natural archive that has been collecting cosmic dust for billions of years. Among the microscopic grains that arrived from distant stars, there could be techno-specks — particles created by alien civilizations.

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 James Webb Space Telescope peered into a disk of gas and dust around a young star where planets are born, and for the first time spotted ice made of heavy water. This water is not ordinary: in its molecules, regular hydrogen is replaced by deuterium, its heavier sibling.

Creating an alloy from several metals is like cooking a soup from mysterious ingredients: guessing the final texture without trial and error is nearly impossible. Conventional models often get it wrong when there are more than three different kinds of atoms.

In the heart of the Milky Way, in the cloud G+0.693, astronomers caught a sweet signal — emission lines of erythrulose, a simple sugar with four carbon atoms and four oxygen atoms.

The young super-Jupiter TWA5B, a scorching ball 25 times Jupiter's mass, floats just fifty light-years away. Its faint infrared glow long hid its chemical makeup. Now, high-resolution spectroscopy with CRIRES+ has registered the ghostly trace of SiO — silicon monoxide.

Imagine a packed orchestra, each musician playing their own part, while you try to pick out the quiet voice of a rare flute: its melody drowns in the sound of violins and trumpets. That's what hunting for molecules in interstellar clouds is like: telescopes pick up the 'radio voices' of countless substances, and picking out the signal you want from the noise is no easy task.

A galaxy is not a static picture but a bubbling cauldron where new stars are constantly born from tenuous gas. To understand how long this boiling will last, astronomers weigh the key ingredient — cold molecular hydrogen. It is invisible itself, but it is betrayed by carbon monoxide (CO), which shines in the radio range.

For nearly half a century, astronomers have been searching for glycine, the simplest amino acid and one of the fundamental building blocks of proteins, in the interstellar medium.

Seven snapshots of the sky after the eruption of Mount Pinatubo. Each snapshot is a map of concentrations for dozens of substances. The question is simple: which substance turns into which? But how do you infer a causal chain from seven frames when you have more variables than time points? M-CaStLe looks at the map differently.

A giant cloud of gas and dust, so cold that its warmth barely flickers, just a few degrees above absolute zero. This is TMC-1 in the constellation Taurus, one of the darkest and densest cradles of molecules in our Galaxy. In recent years, it has become a true treasure trove for astrochemists: the number of substances found there has more than doubled.

Studying the birth of galaxies requires simulating billions of years of dark matter growth and star formation — even supercomputers handle this slowly.

An old chest of family heirlooms opens, and inside lie jewels that were thought to be as old as great-grandmother. But suddenly it turns out: the gold was remelted, the stones were recut, and this happened much later than thought. A similar story happened to the oldest particles in meteorites — calcium-aluminum inclusions, or CAIs.

The Red Planet is surrounded by the rubble of failed worlds — rocky boulders stuffed with metal. Shipping a kilogram of steel from Earth to Mars costs as much as several cars. It's far cheaper to pick up space junk right in orbit.

A star inherits the chemical makeup of its parent gas cloud, just like a child inherits genes from its parents. Astronomers turned this into a method: by measuring the fraction of carbon and other elements with spectroscopy (splitting light into colors), they construct family trees for the stars in a galaxy.

A massive star's explosion is bright but brief. The flash itself lasts weeks, but the dust it heats around it glows in infrared for years. It's like a camera flash illuminating a room, then hot dust particles lingering in the air — only on a cosmic scale.

In the cold gas cloud where a star is born, chemistry sleeps. Molecules barely collide, reactions stall. But when a charged particle zips through the cloud, it knocks electrons off atoms — ionizing them. That's how active ions appear in a dormant cloud, ready to build new molecules.

Radio telescopes detected emissions from the celestial object G358.93-0.03 MM1 — a hot cocoon inside which a massive star is igniting. Within that glow, lines of glycolamide appeared, a delicate carbon molecule.

Long before a star ignites in a gas cloud, chemical life is already bustling. In cold, dense clumps of gas, called starless cores, atoms stick together to form molecules, both simple and complex. To peer into this invisible kitchen, astronomers aimed a 40-meter radio telescope in Yebes at 23 such clouds in the Orion Nebula.

Globular clusters are dense stellar archives, where the youth of the Galaxy is recorded. But reading this chronicle was hindered by imprecise chronometers: age estimates diverged by a billion years.

The light of every star is its unique passport, but the entries are written in the language of spectra and colors. For old giants, such documents are almost indistinguishable: their spectra overlap, and deciphering the details by hand was practically impossible.

At the heart of Omega Centauri, the most massive globular cluster in our Galaxy, thousands of stars are packed so tightly that their light merges into a single glowing blob when seen from Earth. Separating this swarm into individual stars and determining the composition of each is a task akin to sorting through an overfilled anthill.

Previously, generative models for drug discovery worked like an artist painting without choosing a canvas. They learned from existing molecules and simply produced similar ones, without considering how the space of possible compounds is organized. SpaceGFN changes the approach: now chemical space is a construction set where the user specifies the parts and the assembly rules.

The kitchen where stars are baked works on a simple recipe: as much flour as you have, that's how many pies you get. For a long time, astronomers saw a strict relation between a galaxy's mass and how fast it forms stars, and they considered it a standalone rule. But a new study of 24,954 nearby galaxies shows that this relation is just a shadow of two more fundamental laws.

The kitchen of a distant galaxy isn't limited to its bright disk. Around every star system, there's an invisible cloud of gas, like steam above a pot of soup. Astronomers peeked into this steam around galaxies that appear as they were just one and a half billion years after the Big Bang.

When a young star ejects jets of gas, they slam into the surrounding cloud like a fist into a pillow. At the impact site, the gas is compressed and heated — creating a shock wave. In this hot zone, atoms and simple molecules collide and assemble into larger compounds, known as complex organic molecules.