red giant variability

A balloon that lets out air in bursts zips around the room — the jet blasts first one way, then another. A dying star behaves the same way as it sheds its bloated shell. Only instead of air, it's superheated gas, and instead of a balloon, it's a future white dwarf (the dense stellar remnant about the size of Earth).

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.

Betelgeuse, the red supergiant familiar from Orion's shoulder, keeps surprising us. After the mysterious Great Dimming of 2019–2020, when the star suddenly dimmed, it didn't just recover; it changed its ways.

The most massive stars are like overinflated balloons: their envelope stops stretching and instead begins to furiously vent material. At a certain stage, the mass loss becomes so intense that the star stops growing in size. Astronomers see this moment as a kink in the diagram where stars are sorted by luminosity and temperature.

Two hundred and eighty-nine days: that's how long one rotation of the white dwarf white dwarf WD 1532+129 takes. This is not just a record: on its surface, near the magnetic poles, scars of iron and other metals appear — silent testimony to planets it has devoured.

Every fast radio burst is like a resounding strike of a bell in the void. And in its fading ring, the entire structure of space is encoded: over billions of light-years, the radio pulse is slightly delayed by every free electron it meets.

A giant baby planet is still pulling in leftover building material from its surrounding cloud. That's the scene the Hubble Space Telescope captured when it aimed its cameras at an object catalogued as SR 12 c. This companion planet orbits a young star at a wide distance — farther out than Neptune is from the Sun.

Images from the James Webb Space Telescope have revealed unexpectedly intense light from the first galaxies — colossal star systems that formed shortly after the Big Bang. Imagine a toaster browning a slice of bread in a minute, while an oven takes an hour to bake a loaf — the result is essentially the same.

If you turn on a lamp in a room, it illuminates the walls. But if you place the same lamp in a vast hall, the light barely reaches the corners. Similarly, radiation from young stars affects gas in a galaxy: it knocks electrons out of hydrogen atoms, making the gas glow.

Axions are hypothetical elementary particles introduced in 1977 by Roberto Peccei and Helen Quinn to resolve the so-called strong CP problem in the Standard Model of particle physics.

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.

At the center of the Milky Way lies the supermassive black hole Sagittarius A*. It is four million times more massive than the Sun, but by cosmic standards it behaves quietly: it only occasionally flares up when it swallows a clump of gas.

A lighthouse blinks every few seconds, but then begins to slowly brighten and dim over the course of a year. That is exactly what about a third of red giants do — huge stars in the late stages of life. Their normal pulsations take days or weeks, but on top of that, long secondary periods are visible: months and years.

A red giant is a star that has swelled up, cooled on the outside, and become hundreds of times larger than the Sun. Inside, it's far from calm: layers of gas oscillate like a giant bell, causing its brightness to flicker slightly. Astronomers pick up these oscillations to probe what's happening deep within.

The night sky looks still, but many stars tremble like a drum after a strike. For seven straight years, the TESS satellite stared at the same patches of sky and caught this trembling in 19,151 red giants — old, bloated stars. Previously, far fewer of these 'singing' giants were known, and now the list has grown by 80%.

The Sun is not a perfectly steady lightbulb. Its brightness quivers slightly: it dims a bit, then brightens. For Earth's climate, even slow variations stretched over thousands and millions of years matter. They could have left their mark in the geological record of the last 540 million years. Astronomer [scientist:A. M.

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.

If a supermassive black hole lives at the center of a galaxy, it heats the infalling gas to incredible temperatures. That gas glows, and we see it as a quasar — the brightest beacon in the universe. But how do you measure the size of the light source itself?

A red giant in the constellation Cygnus has swelled so much that its outer layers are spilling onto a small but heavy neighbor — a white dwarf. The gas swirls around the dwarf like water down a bathtub drain, falling onto it. But in CH Cygni, this flow is not calm: every 682.5 seconds, the X-ray emission flares and fades.

The young star RY Tau is like a finicky spinning top. Around it whirls a flat disk of gas and dust — the leftovers of the cloud from which the star was born. The star pulls some of the disk's matter toward itself like a vacuum cleaner, and flings some back out in a narrow wind cone like a fountain.

In a dense gas cloud where a star heavier than the Sun is forming, there is a tiny source of radio waves. It works like a laser: methanol molecules amplify the radiation, and we see a bright spot. But this spot behaves strangely: its brightness jumps up and down within a matter of hours.

A red giant is like a balloon slowly letting out gas. The star swells, its outer layers weaken, and stellar wind carries mass into space. But exactly how much does a star lose? This is a crucial question: the answer determines what kind of remnant it will leave behind — a white dwarf, a neutron star, or a black hole.

A pulsar is a dead star spinning at breakneck speed, sending out radio pulses like a lighthouse. Usually these pulses arrive right on schedule, but occasionally there are true monsters among them — giant pulses that are thousands of times brighter than normal.

Betelgeuse is a giant star ready to explode as a supernova. But it may not be alone: a small companion star, Sivarkha, circles in a tight orbit. Every 2000 days, it plunges through Betelgeuse’s outer layers, like a boat cutting through water, leaving waves of superheated gas.

Far beyond the Solar System, a world called VHS 1256B wanders — a giant planet without a star. For a long time, astronomers couldn’t figure out why its brightness jumped by nearly 40% in just a few days. The answer came with the James Webb telescope: it turns out, colossal storms of silicate dust engulf the entire planet.