[url=http://www.telegraph.co.uk/science/space/10244688/Most-powerful-magnetic-field-in-universe-that-is-20-trillion-times-stronger-than-a-fridge-magnet.html?fb]Article:[/url] [quote]The strongest magnetic field in the universe has potentially been discovered – a dead star that packs the equivalent mass of our sun into an area just 12 miles across. The former star, which has the catchy name SGR 0418+5729, is 6,500 light years from Earth and was initially thought to have an unusually low magnetic field. New observations using the European Space Agency’s XMM Newton Space Telescope have, however, revealed that it may be the strongest magnetic source in the known universe. Astronomers estimate that it produces a magnetic field around 20 trillion times stronger than a standard refrigerator door magnet. The dead star is a kind of neutron star called a magnetar – the dead core of a once massive star that has collapsed in on itself. These produce extremely dense objects that sporadically throw out X-rays and gamma rays as they rotate. “Until very recently, all indications were that this magnetar had one of the weakest surface magnetic fields known,” said Dr Andrea Tiengo of the Istituto Universitario di Studi Superiori, Pavia, Italy, who led the study. “It was roughly a 100 times lower than for typical magnetars. Understanding these results was a challenge. “However, we suspected that SGR 0418 was in fact hiding a much stronger magnetic field, out of reach of our usual analytical techniques.” SGR 0418 was first discovered in 2009 by Nasa’s Fermi space telescope and the Russian Koronas-Photon observatory. At the time it appeared to have one of the weakest magnetic fields of any magnetar discovered, but analysis of observations by the XMM Newton space telescope have shown otherwise. Magnetars spin a complete rotation within just a few seconds. By measuring the rate at which the spin of a magnetar declines allows astronomers to calculate its magnetic field. Dr Tiengo and his colleagues, however, used a new technique that searches for variations in the X-rays given off by the magnetar as it rotates. They calculated that SGR 0418 must have a magnetic field of more than 1 quadrillion, or 1,000 trillion, gauss, the unit used to measure the strength of a magnetic field. By comparison, the iron core of the Earth is thought to have a magnetic field of 25 gauss. Physicists have estimated that the upper limit for a magnetar would be 100 quadrillion gauss, but none have been found to be this powerful yet. “To explain our observations, this magnetar must have a super-strong, twisted magnetic field reaching 10^15 Gauss across small regions on the surface, spanning only a few hundred meters across,” said Dr Tiengo. “On average, the field can appear fairly weak, as earlier results have suggested. But we are now able to probe substructure on the surface and see that the field is very strong locally.” The researchers, whose findings are published in the journal Nature, now hope the new technique may help them discover other hidden magnetars and may help reveal more about those that have already been identified. Norbert Schartel, ESA’s XMM-Newton project scientist, said: “The spectral data provided by XMM-Newton, combined with a new way of analysing the data, allowed us to finally make the first detailed measurements of the magnetic field of a magnetar, confirming it as one of the largest values ever measured in the universe." “We now have a new tool to probe the magnetic fields of other magnetars, which will help constrain models of these exotic objects.”[/quote]