A neutron star with a mighty magnetic field has thrown down the gauntlet to theories about stellar evolution and the birth of black holes, astronomers said today. The "magnetar" lies in a cluster of stars known as Westerlund 1, located 16,000 light years away in the constellation of Ara, the Altar.
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 cluster is also, by the standards of the Universe, very young. The stars were all born from a single event just three and a half to five million years ago.
Within Westerlund 1 is the remains of one of galaxy's few magnetars - a particular kind of neutron star, formed from the explosion of a supernova, that can exert a magnetic field a million, billion times strong than Earth's.
The Westerlund star which eventually became the magnetar must have been at least 40 times the mass of the Sun, according to the study, which appears in the research journal Astronomy and Astrophysics. If so, intriguing questions are raised.