Astrophysicists have leveraged advanced models to map the minuscule surface features on neutron stars, finding these 'mountains' limited to less than a millimeter high by the stars' immense gravitational pull.
When massive stars explode as supernovae, much of their material scatters across the universe. Their cores collapse under extreme density, fusing protons and electrons into neutrons to form a neutron star—a stellar remnant packing the Sun's mass into a 22-kilometer sphere. Stars from 8 to 60 solar masses typically follow this path; lighter ones yield white dwarfs, heavier ones black holes.
Such density creates extraordinary gravity that flattens surface topography. Prior research estimated neutron star 'mountains' at just centimeters before crustal failure. Now, more realistic simulations show they're even smaller—fractions of a millimeter tall. On an Earth-sized scale, they'd measure about 50 centimeters. The thin hydrogen-helium crust is thus incredibly smooth, shaped by spin changes or accreted matter from companions, per researchers led by University of Southampton astrophysicist Fabian Gittins. Findings were shared at the 2021 National Astronomy Meeting.
These features were eyed for generating detectable spacetime ripples, but latest results indicate they're too subtle for current tech. No continuous waves from single neutron stars have been spotted. "We'd need third-generation gravitational-wave detectors," Gittins notes.
The €1.9 billion Einstein Telescope, a proposed European project, could enable this—now included in the roadmap for future flagship science initiatives, pending approval.
