In the news today ..
"How Much Mass MAkes a Black Hole? Astronomers Challenge Current Theories"
http://www.physorg.com/news201335702.html
"Using ESO's Very Large Telescope, European astronomers have for the first time demonstrated that a magnetar -- an unusual type of neutron star -- was formed from a star with at least 40 times as much mass as the Sun. The result presents great challenges to current theories of how stars evolve, as a star as massive as this was expected to become a black hole, not a magnetar. This now raises a fundamental question: just how massive does a star really have to be to become a black hole?"
....
"By comparison with these stars, they found that the star that became the magnetar must have been at least 40 times the mass of the Sun. This proves for the first time that magnetars can evolve from stars so massive we would normally expect them to form black holes. The previous assumption was that stars with initial masses between about 10 and 25 solar masses would form neutron stars and those above 25 solar masses would produce black holes."
Magnetars are very cool (... er hot ...) objects. A giant magnet in the sky ..
Cool flyby video in the article, too.
Cheers
