Astrophysicists have recently used new models to map the tiny landforms developed on the surface of neutron stars. According to this work, the latter would be extraordinarily small due to the intense gravitational attraction of these objects, reaching less than a millimeter in height.
Some massive stars explode in supernovae. A large part of the matter is then seeded in the Universe. During this time, the cores of these stars, which collapse during the explosion, become so dense that protons and electrons can combine to form neutrons. This creates a "neutron star":an exceptionally dense stellar corpse. Imagine the mass of the sun compressed into a sphere about twenty-two kilometers in diameter. Most stars between 8 and 60 solar masses end their lives this way. Below this range you get a white dwarf. Above you get a black hole.
Naturally, such dense objects develop an exceptional gravitational attraction which is not without consequences for surface reliefs. Previous work has suggested that "neutron star mountains" - as the researchers call them - could only be a few centimeters high, after which the crust would break up and the landforms would fall back.
According to a recent study, which relies on new models allowing more realistic simulations of what neutron stars look like, it seems that these structures are in actually even smaller than expected, reaching only fractions of a millimeter in height . For comparison, if we were to report an Earth-sized neutron star, these mountains might be only about fifty centimeters high.
In other words, the surface of these stars – a thin crust of hydrogen and helium – would therefore be incredibly smooth . Causes of these "distortions" could include changing the star's rotation rate and accretion of matter stolen from another star, the researchers point out. These results, led by astrophysicist Fabian Gittins, from the University of Southampton (UK), were presented at the National Astronomy Meeting 2021.
Until now, astronomers have thought that these landforms might be large enough to be able to produce ripples in the fabric of spacetime that we could detect. However, these latest results suggest that these waves could be much more difficult to spot than expected. These waves from single neutron stars have yet to be observed, but "we would only be able to do that with third-generation gravitational-wave detectors “, assures Fabian Gittins.
We then think of the Einstein Telescope. It is not yet known whether this European project at 1.9 billion euros will actually see the light of day, but it has just been integrated into the roadmap of future major scientific projects.
