Scientists in Spain and Portugal have developed a theoretical model and discovered with the help of it new types of bosonic stars - hypothetical objects that do not consist of fermions, like ordinary stars, but bosons. Such stars can be donut-shaped, but quickly disintegrate due to external disturbances. This was announced in a press release on Phys.org.
Bosons are particles that can be in the same quantum state. This distinguishes them from fermions (for example, electrons), which are subject to the Pauli exclusion principle. Fermions are usually made up of matter, and some bosons, such as photons, are carriers of interactions. At the same time, it is believed that dark matter can be composed of ultra-light particles, which are also bosons.
The property of bosons to be in the same state is hypothetically capable of leading to the appearance of macroscopic objects and even exotic stars. In a new work, astrophysicists have found out whether rotating bosonic stars can be stable. To do this, they used a numerical model based on Einstein's general theory of relativity.
The researchers considered two scenarios. In the first, a large cloud of bosonic matter collapses to form a spinning star. In the second scenario, the scientists checked whether the already emerging bosonic star is resistant to disturbances or not. Rotating bosonic stars can be of one of two types. Scalar stars are formed by spin-zero particles, while vector stars are formed by spin-1 particles.
Scientists have found that scalar stars are torus-shaped, while vector stars remain spherical, but flattened at the poles. In this case, toroidal stars are unstable to perturbations and disintegrate into parts with the possible formation of a black hole. Spheroidal stars are stable like normal stars.
In the future, physicists plan to find out whether scalar stars are always unstable or whether it depends on the properties of the dark matter particles of which they are composed.