stellar feedback

In the first half-billion years after the Big Bang, galaxies grew like crazy. Gas fell in rapidly and collapsed into stars without any resistance. This period is called 'unimpeded star formation.' It's like frying pancakes on a scorching skillet without a lid: splatters fly, but nothing holds them back.

A vast city lights new streetlamps every night. But then a hurricane sweeps in, rips all the fuel from the warehouses, and the lamps go out one by one. Something similar has been spotted by astronomers in a galaxy whose light has traveled 12.5 billion years to reach us.

In the heart of a molecular cloud, a massive star is born. Its ultraviolet light ionizes hydrogen, and the cloud flares in the Lyman-alpha line. But for the photon, this flare is not liberation but imprisonment in a hall of mirrors.

In the heart of the Eagle Nebula, about 7000 light-years away, three giant pillars of gas and dust rise — the Pillars of Creation. Their shape is familiar to many from Hubble Space Telescope images. Now, Webb's infrared camera has allowed us to peer inside these dense cocoons where stars are born.

Two swift streams of charged particles collide, and magnetic field lines begin to tear and reconnect. This process powers solar flares and auroras. It was usually assumed that all particles behave alike, like bullets from the same gun. But each particle has a tiny top: its intrinsic rotation, or spin.

Two neutron stars are two city-sized spheres with the mass of the Sun. As they spiral together, tidal forces stretch each one, as if a giant hand were squeezing and twisting a rugby ball. The star begins to oscillate — density waves run through it, like ripples on water from a thrown stone.

A colony of cells is like a city that grows from its outskirts: new houses appear where there's more space. Inside, it's crowded, and construction stalls. Similarly, cells divide more often at the edge, where neighbors squeeze them less. Scientists modeled this without any chemical commands — only mechanics. In the model, each cell is a ball that presses on others.

In a blacksmith's forge, a blast of air fans the glowing coals, and shock waves blow bubbles of hot gas. In galaxy centers, a supermassive black hole drives the same process. Its narrow plasma jets, like bellows, punch through the surrounding space and create bubbles visible in X-rays.

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

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.