helium star

Imagine three witnesses who saw the same event. Two tell the same story, the third tells a different one. Whom do you believe? This is exactly the situation in astronomy when measuring carbon in the star J0815+4729, an ancient object with a record-low iron abundance (carbon is one of the key elements used to infer the properties of the…

Two spinning tops whirl so close they nearly touch. One is scorching blue, the other dim white. Together they complete a full orbit in twenty hours. This is the pair Feige 64: a blue star with a mass of just a third of the Sun's, and a white dwarf, the cooled core of a former star, one and a half times heavier than our Sun. The blue star seems too hot for its mass.

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.

Around young stars, flat clouds of gas and dust swirl: these are future planetary systems. Inside some of them, a void gapes: the dust and gas have been swept away, as if someone thinned out the middle of a vinyl record.

At a distance of 1900 parsecs, in the constellation Vulpecula, the star V420 Vul pulsates — a Mira-type variable. Such stars, nearing the end of their lives, swell and shed their outer layers. But around V420 Vul, astronomers spotted not just a shed envelope, but something trickier.

1799 kilometers per second — that's the speed at which star S5-HVS1 is permanently leaving the galaxy. 4.8 million years ago, it was ejected from the center of the Milky Way during a close encounter with the supermassive black hole Sgr A*.

In 2024, the team led by David Charbonneau pointed the Magellan telescope with the WINERED spectrograph at LHS 1140. During transit, high-resolution spectroscopy caught the absorption line of metastable helium at 10833 Å.

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.

A world where a year lasts just one and a half Earth days, and the star in its sky is hundreds of times larger than our Sun. This is KELT-9 b — a gas giant heated to temperatures at which iron vaporizes. Its atmosphere is not just hot; it is literally boiling away into space, like steam rising from a giant cauldron.

A planet the size of Neptune, but glowing white-hot. Beneath the clouds lies an ocean of magma capable of absorbing an entire hydrogen atmosphere. The new SEAMIST model is the first to trace how such dissolution changes a planet's fate from birth to old age. The big surprise is the mechanism of catastrophic boiling.

On April 1, 2026, satellites recorded a bright fireball blazing in the sky over the South Atlantic. Photometric tracking satellites detected the entry and demise of the object at an altitude of 90.5 km. An ordinary asteroid? No. Astronomers recalculated the velocity vector into the heliocentric system — and gasped: 51.73 km/s.

An archaeologist holds in their hands not a clay shard but an actual star — a living snapshot of the era when the universe was just learning to produce anything heavier than lithium. That is exactly the kind of find astronomers describe in a new study. They spotted four dim stars so ancient and pristine in composition that their matter is barely diluted by the 'cosmic dust' of later generations.

In the crowded center of the galaxy, two stars orbit so close together that one strips the outer layers off the other, like wind blowing off a coat. What remains is a hot helium core, a star without a hydrogen envelope.

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.

A stellar river winds around the center of a distant galaxy like a glowing ribbon on an invisible frame. That frame is the dark halo: a vast cloud of invisible dark matter whose gravity holds stars and gas in place. If the halo is squashed like a pumpkin or stretched like a melon, the stellar stream will bend differently.

A match flares from both ends. First the head ignites, and a moment later the flame engulfs the wooden stick. Something similar may happen in some Type Ia supernovae — except the match is a white dwarf (a star the size of Earth), and the flame is a thermonuclear explosion.

The halo of our Galaxy is a huge, sparse cloud of old stars that envelops the familiar disk. It holds the story of how the Milky Way grew by gobbling up neighboring dwarf galaxies.

A pulsar is a dead star spinning at breakneck speed, sending out radio pulses like a lighthouse. But for PSR J1928+1815, the signal sometimes cuts out for 3.6 hours. Something is blocking the beacon. A companion star orbits the pulsar, and its shadow falls on us.

Ancient stars, nearly devoid of heavy elements, are like fossilized remnants of the first cosmic flashes. For a long time, the odd ratio of carbon, hydrogen, and helium in three such stars was thought to require a hypernova — an ultra-bright supernova with hundreds of times more energy than a regular one.

Water isn't the only thing life needs. To assemble the first RNA-like chains from simple molecules, you need ultraviolet light, like the sunlight that helps plants, but harsher and with shorter wavelengths. Big stars like the Sun emit plenty of this light. Small, dim stars, however, have almost none: they shine mostly in red and infrared, like a glowing ember.

On the outskirts of galaxy M83, also known as the Southern Pinwheel, a river of ancient stars drifts through the void. It stretches 81 kiloparsecs — roughly 264,000 light-years, two and a half times the diameter of our Milky Way.

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.

Deep in the Galaxy, runaway stars are sometimes born. A monstrous force, a supernova explosion, flings them from their usual place. One such wanderer has recently been found: a star of the LP 40-365 class, a fragment of a white dwarf that survived an incomplete explosion.

A planet hugging its star is like an ice cube forgotten on a scorching skillet. The ice melts and evaporates, except instead of water, it's hydrogen and helium from the planet's upper layers.

When a star like the Sun runs out of hydrogen, it swells into a red giant, and helium piles up in its core. At some point, the helium ignites — in a few seconds, it releases as much energy as the star had radiated over thousands of years. This is a helium flash.

In radio sky data, like on old photographic film, two bright gas streaks have emerged. They move at different speeds but hang near the same dim star. The star and the streaks turned out to be inside a huge empty bubble in the interstellar gas. This bubble is like a blown soap bubble left over from an ancient supernova explosion.

Imagine a city where streetlights shine, but their glow isn't scattered by fog — instead, it streams into the sky almost entirely. That's what galaxy U37126 looks like, as seen by astronomers in the early universe with the James Webb Space Telescope. Its light has traveled for more than 13 billion years to reach us.

In stellar nurseries, massive stars are not born alone but in pairs. Two stars orbit a common center, and the more massive one expands first and begins to shed its outer layers. Some of this material doesn't escape into space but flows onto the companion, like water from an overflowing cup into a cup held beneath.

An ordinary lump of coal left under the blazing sun just heats up. But if you take it into space and bring it twenty times closer to the Sun than Earth is, it won't survive for more than a few minutes. That's roughly how dark, carbon-rich asteroids behave. They are rarely found on orbits that dive deep inside Mercury's orbit.

The night sky seems full of stars, but between them lurk clouds of gas where not a single star has ever ignited. Such objects are called dark galaxies: they contain enough gas, but it is too diffuse and cold to collapse into stars.

Planet WASP-121b orbits so near its star that the fierce heat boils its atmosphere away, streaming like a comet's tails. With the James Webb Space Telescope, astronomers continuously watched this process for the first time.

On November 23, 2023, the LIGO, Virgo, and KAGRA detectors caught a gravitational wave from the merger of two black holes with masses of 137 and 103 solar masses. Both fall into the pair-instability mass gap, the range from 69 to 139 solar masses where ordinary stellar evolution leaves behind nothing but expanding gas.