GOBBLING gas from a neighbour should make neutron stars spin faster, but sometimes the exact opposite happens. Now there might be an explanation: the gas arrives 鈥渂ackwards鈥�.
Neutron stars are dense, fast-spinning stellar corpses that can pull material from a smaller orbiting star, spooling it into a disc before gobbling it up. This material carries momentum, which is why the neutron star should spin faster.
But when Demos Kazanas at the NASA Goddard Space Flight Center and his colleagues looked at 18 years鈥� worth of X-ray observations of neutron stars in binary systems in the Small Magellanic Cloud, they found that half were slowing down 鈥� at the same rate as the others were accelerating.
Advertisement
Kazanas and his team suggest that slowdowns happen when the swallowed gas is spooling around the neutron star in the opposite direction to the star鈥檚 spin ().
If backed up by further observations, the idea could drastically change our view of the way neutron stars evolve, Kazanas says.
This article appeared in print under the headline 鈥淏ackspinning meal slows neutron star鈥�