The neutron star in question was just overweight. It was formed by the fusion of two smaller neutron stars. This usually results in an object so massive that it collapses almost instantly under its own gravity and turns into a black hole. But in this case, a neutron star remained in the astronomers’ field of view for a day, and then the object faded out of sight.
“The existence of such a massive neutron star with such a long life expectancy is usually not considered possible,” said Nuria Jordana Mitjans, an astronomer at the University of Bath in England. “It is a mystery why this star was so long-lived.” It seems that something prevented the neutron star from “noting how massive it is”. One possibility is that the star was spinning so fast and with such strong magnetic fields that its collapse was delayed – like water staying in a tilted bucket if you rotated it fast enough.
Observation with consequences
The observations also raise questions about the source of the incredibly energetic flashes known as short gamma-ray bursts (GRB). It was previously assumed that these flashes – the most energetic event in the universe since the Big Bang – emanate from the poles of a newly formed black hole. However, in this case, the observed GRB must have emanated from the neutron star itself, indicating an entirely different process.
Neutron stars are the smallest and most massive stars in existence. They are midway between regular stars and black holes. It has a diameter of about 20 kilometers and is so dense that the mass of a teaspoon of the substance is one billion tons. They have a smooth shell of pure neutrons that is ten billion times stronger than steel.
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