Magnetic mega-star discovery challenges black hole theory

Westerlund 1, discovered in 1961 by a Swedish astronomer, is a favoured observation site in stellar physics. It is one of the biggest cluster of superstars in the Milky Way, comprising hundreds of very massive stars, some shining with a brilliance of almost a million Suns and some two thousand times the Sun's diameter.

...
The mainstream assumption is that stars of between 10 and 25 solar masses go on to form neutron stars. But those above 25 solar masses produce black holes -- the light-gobbling gravitational monsters that are formed when a massive, dying star collapses in on itself.

In that case, the magnetar's mother should have become a black hole because it was so big.

source: http://www.telegraph.co.uk/science/space/7952620/Magnetic-mega-star-discovery-challenges-black-hole-theory.html