Scientists calculated a weird type of star that can spin even faster than a black hole's speed limit.
March 19, 2026
Original Paper
Energy extraction from a rotating Buchdahl star via magnetic reconnection
arXiv · 2603.17928
The Takeaway
While black holes have a maximum possible rotation speed before their math breaks down, 'Buchdahl stars' are dense enough to mimic black holes but lack an event horizon. This allows them to spin at extreme rates that would be impossible for a black hole, potentially making them the most powerful energy-extracting engines in the universe.
From the abstract
In this work, we investigate the magnetic reconnection (MR) process as a mechanism for energy extraction from a rapidly rotating Buchdahl star (BS), one of the most compact horizonless objects that can, in principle, possess a spin parameter exceeding the extremal limit of a black hole (BH). We explore the energetics of the BS by focusing on the newly proposed MR mechanism developed by Comisso and Asenjo (the Comisso-Asenjo mechanism). Within this framework, we evaluate the energy extraction eff