THE awesome power of an X-ray telescope orbiting Earth has revealed a sizzling hotspot on the surface of a neutron star some 500 light years away. The spot is about 60 metres across, making it the smallest feature ever seen outside the solar system.
The neutron star, called Geminga, is a super-dense ball of subatomic particles left over after a massive star died in a supernova. It measures about 20 kilometres across and has an average temperature of around 500,000 掳C. But when Patrizia Caraveo and colleagues from the Institute of Space Astrophysics and Cosmic Physics in Milan, Italy, pointed the XMM-Newton space telescope at Geminga, they saw high-energy X-rays that had to be coming from something hotter (Science, vol 305, p 376).
The X-rays, they discovered, are coming from a hotspot with a temperature of about 2 million 掳C, four times as hot as the rest of the surface. Caraveo鈥檚 team worked backwards from the observed brightness of the hotspot to estimate its size. The spot is probably created by the star鈥檚 magnetic field funnelling nearby charged particles onto the surface, says Caraveo.
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