millimeter emission

The Tarantula Nebula is a giant stellar nursery in a neighboring galaxy. Hundreds of thousands of stars are born there, and their light illuminates clouds of dust. This dust glows in the infrared, and its spectrum shows mysterious bands. For a long time, astronomers debated which molecules produce them.

The galaxy cluster RXC J0528.9−3927 is like a city shrouded in fog: at its center, a radio halo shines brightly, but farther out, beyond the usual boundaries, astronomers have spotted a barely visible glow. It stretches for two million light-years — three times farther than the halo itself.

An ordinary flashlight shines in all directions, and after just a couple of dozen meters its beam fades so much it barely lights a wall. The atmosphere scatters light, and wind and heat currents distort it even more. But if you lay an invisible pipe for light right in the air, the beam will travel through it like water through a hose.

Every morning, a janitor sweeps leaves into a pile. The Sun, as it travels through the galaxy, does something similar: its gravity gathers diffuse interstellar gas into an invisible cone — a giant funnel.

Ten billion years ago, the universe was speckled with strange crimson sparks. The JWST spotted them in images at distant redshifts — compact sources blazing like entire galaxies yet no larger than a tiny central region. Astronomers nicknamed them “little red dots.” Their nature long defied explanation.

When the James Webb Space Telescope turned its gaze deep into time, astronomers expected to see familiar galaxies. Instead, the images were dotted with a scattering of bright, incredibly compact red dots.

The cosmic microwave background is the afterglow of the Big Bang, which we see at millimeter wavelengths. But it also has a long-wavelength tail extending into the radio range.

The XRISM X-ray telescope spent 170,000 seconds staring at the core of galaxy Cygnus A — one of the most powerful radio sources in the sky. At its center lurks a supermassive black hole that sucks in matter and heats it until it glows in X-rays. The instrument caught light from iron atoms that had lost electrons.

A pair of figure skaters spins while holding hands. If their path is a perfect circle, each push from a partner is predictable. But stretch that path into an oval, and the effort becomes uneven: a jerk as they come together, a lull as they pull apart. Something similar happens with two black holes in the final minutes before they merge.

A young star is surrounded by a flat, rotating disk of gas and dust, like pizza dough that's been spun out. Planets are born inside such a disk. But around three stars (Elias 2-24, IM Lup, and DM Tau) astronomers noticed something odd: far beyond the edge of the bright disk stretches a barely visible but enormous dust halo.

At the very heart of the Milky Way, something is continuously glowing in gamma rays. This light is special: its energy is exactly 511 thousand electronvolts. Such energy is produced when an electron meets its antimatter counterpart, a positron, and they annihilate, leaving behind a flash of light.

A dust grain hangs in the air, held by an invisible beam of light. Around it is ordinary air, but sometimes a tiny spark jumps across the grain. For the first time, scientists have observed such discharges up close and found that they are triggered not by the grain itself, but by invisible visitors from space and from the ground.

A newborn star is like a kitchen mixer: it whips up the surrounding cloud, and splatters fly in all directions. Only instead of batter, it's gas and dust. Previously, astronomers had only seen gas jets, and dust was considered too fragile: the shock wave should shatter dust grains into atoms.

Light from distant stars, as it travels through cosmic dust, loses some of its energy. Dust grains absorb and scatter light, and the way they do so at different wavelengths reveals their composition and size. Astronomers call this the dust extinction curve.

Above Jupiter's poles, auroras blaze as electrons are accelerated by electric fields and slam into the upper atmosphere, making the gas glow. But not all electrons head downward. Some, it turns out, get a kick in the opposite direction — away from the planet, into deep space.

The night sky is no longer as quiet as it used to be. Thousands of satellites are whizzing overhead, and each one can accidentally emit radio waves, interfering with astronomers trying to listen to distant galaxies. To make sense of this noise, scientists pointed the 21CMA radio telescope in China at Starlink satellite passes.

A swarm of fireflies in a night forest flashes randomly: each beetle blinks on its own, and the light scatters equally in all directions. Now imagine the fireflies agreeing to blink so that their combined light goes only north — even though they stay put and none of them turns. That's roughly what physicists did with atoms inside a thin glass tube.

In the Andromeda galaxy, our Milky Way's nearest large neighbor, astronomers have spotted giant cold clouds where stars are born. These clouds are made of gas and dust, but seeing them directly is tricky: they barely shine.

A solar flare is like thunder on a clear day: a short but powerful burst of energy. The MeerKAT radio telescope in South Africa caught one such M1.3-class flare and examined it with unprecedented clarity. Ordinary instruments see either bright details or faint ones, but not both at once.

A radio telescope has caught signals from three galaxies that existed when the universe was less than a billion years old. Their radio glow is so powerful that each seems to be birthing a thousand suns per year in a short span. For comparison, our Milky Way produces only a couple of stars per year.

A solar flare is like an explosion in a star's atmosphere: in minutes, it releases energy comparable to billions of nuclear bombs. On May 4, 2022, the RT-7.5 radio telescope in Moscow was watching an M5.7-class flare. The instrument was catching millimeter radio waves: those shorter than a centimeter and invisible to the eye.

In Chile's Atacama Desert, at an altitude of nearly five kilometers, stands a radio telescope that catches millimeter waves from the depths of space. These waves carry the heat of distant galaxies, but first they must pass through a window — a thin plate of silicon that separates the cold receiver from the warm outside world.

A diamond speck smaller than a hundredth of a millimeter glows red. Inside it is a crystal defect: two neighboring carbon atoms, where one is missing and a nitrogen atom sits nearby. Such a pair captures light and re-emits it, like a tiny beacon that doesn't fade at room temperature. This speck was brought near a pathway on the chip's surface.

The Einstein Probe space telescope detected a celestial storm: after a short (0.4-second) gamma-ray burst — a cosmic lightning bolt — came a long roll of X-ray thunder. It lasted nearly 10 minutes. This is the first direct proof that such explosions leave a lingering X-ray afterglow.

Astronomers nicknamed them 'little red dots' — distant galaxies where a giant black hole hides at the center, wrapped in a thick layer of hydrogen. This packaging isn't just camouflage; it's a natural cannon. The black hole sucks in matter, but some of it is spat back out in narrow jets.

The red dwarf V374 Pegasi is a star one-third the size of the Sun, but with the temperament of a volcano. Every few hours, giant clumps of plasma tear away from its surface, like steam bubbles from a boiling cauldron. These ejections, called prominences, fly off into space and generate bursts of radio waves.

At the center of nearly every large galaxy sits a supermassive black hole. It pulls in gas and dust, and a bright disk swirls around it. But the James Webb Telescope looked further out — into a region where the black hole's light is weaker, yet the dust still glows. Astronomers examined eight galaxies.

On the night of March 9–10, 2024, a cloud of plasma ejected by the Sun raced away from the star. It had already passed a distance of five solar radii when a ground-based array of 352 antennas in California's Owens Valley caught a brief radio signal from it.

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.

The RATAN-600 radio telescope is a ring of hundreds of aluminum panels on a mountainside in Karachay-Cherkessia. In the spring of 2018, its mirror caught radio waves from sixteen red dwarfs — small, dim, but very long-lived stars.