The Birth of a Gravastar: How a Star Escapes a Black Hole ⚡ экспресс
The mechanism of dynamic formation of a gravastar — a horizonless black hole mimic — has been studied without invoking higher curvature corrections. The initial model is the collapse of a homogeneous dust sphere (Oppenheimer–Snyder scenario). It is shown that with fine-tuning of parameters, a de Sitter region of zero initial size can emerge at the center of the collapsing sphere, which then expands. The expansion naturally slows down near the Schwarzschild radius, where it meets the infalling dust surface, forming a static equilibrium. Furthermore, a maximum initial compactness of the collapsar C=3/8 has been established; exceeding this threshold makes black hole formation inevitable. The results provide the first example of self-consistent gravastar formation within classical general relativity and pave the way for assessing the astrophysical realism of such objects.
A dying massive star usually shrinks into a black hole—a trap from which even light cannot escape. But another finale is possible: a gravastar—a bubble of dark energy, the mysterious force pushing the cosmos apart.
Simulations of a collapsing cloud revealed: deep in the center, a tiny nugget of dark energy is born. It inflates, like a soap bubble in a vacuum. Upon reaching the critical radius where a black hole would normally appear (first calculated by Karl Schwarzschild), the expansion halts. Infalling matter hangs suspended on the bubble—a stable gravastar is born. The surprise: inside, space stretches as rapidly as in the first moments after the Big Bang—a whole mini-universe beneath the shell.
The trick doesn't always work. The star must be sufficiently 'fluffy': its mass-to-radius ratio (in special units) must be less than 3/8. Otherwise, collapse into a black hole is inevitable.
🎯 Inside a gravastar, space expands like a newborn Universe—a miniature cosmos hidden from us by a glowing shell.