Friday, March 1

Discovered a “strange star” so light that it defies astronomical theories

In an article published this Monday in Nature Astronomy A small and extremely light neutron star is described, with a radius of about 10 km and a mass only 77% of that of the Sun. This star, lighter than theoretically expected, may add to our understanding of the state in which the dense and cold matter in the Universe is found, its discoverers assure in a press release.

Neutron stars typically have a mass 1.4 times that of the Sun and a radius of just tens of kilometres, making them one of the densest objects in the Universe. However, its mass is known to range between 1.17 and 2.35 times that of the Sun.

Victor Doroshenko and colleagues have calculated the mass of a neutron star found in the supernova remnant known as HESS J1731-347. At 0.77 solar masses, it is smaller than expected and defies current understanding of stellar physics.

The authors argue that this object might not be a normal neutron star, but a more exotic – and not yet discovered – object known as a “strange star”, a hypothetical star made of the same stuff as quarks. Quarks are elementary particles that, when combined, form the neutrons and protons of the atom.

In the center of supernovae

Neutron stars have been widely studied in the past because they can be relatively easy to identify: they sometimes emit abundant X-rays and are often found in the center of supernova remnants.

However, an optically bright star recently found in the same location (HESS J1731-347), allowed Doroshenko and his co-authors to determine the distance to the pair of stars, and thus calculate the mass of the neutron star and the density of matter. inside.