A Stellar Cocoon for the Little Red Dots express
A star weighing a hundred thousand Suns lives bright and brief. Its finale is a rapid collapse into a black hole. But just before the end, it manages to wrap itself in a dense gas cocoon. It is precisely such cocoons that the James Webb Space Telescope discerns around enigmatic objects — the "little red dots."
Astronomers took five models of supermassive stars with different compositions and traced their lives step by step. It turned out that a star loses mass not in a steady stream but in sharp bursts, like a steam boiler that periodically releases jets of vapor. In one model, the closest to early Universe conditions, there were four such episodes. Each lasted from forty to three hundred years and ejected from ten to three hundred fifty solar masses of gas.
This gas cocoon is composed mostly of hydrogen and helium, but with a chemical quirk: it has unusually high nitrogen compared to oxygen. This signature will help distinguish this mechanism from others. After shedding the shell, the star itself lives for about another million years, then collapses into a black hole within hours — a ready-made "seed" for future giants at the centers of galaxies.
The final gas ejection from a supermassive star lasts less than three hundred years — by cosmic standards, that's shorter than a blink of an eye.
In Arthur C. Clarke's novel Rendezvous with Rama, humanity encounters a giant alien spacecraft resembling a dense cocoon — what is that if not a little red dot that has passed through the crucible of stellar evolution?