PureInsight | January 3, 2001
Neutron stars are the walking corpses of the cosmos. But these weird objects, dense beyond belief, can pack a lively wallop.
A big star ends its life in a giant explosion called a supernova. If the star is massive enough -- roughly four to eight times more massive than our Sun -- and the conditions right, the core implodes, forming a very dense state of matter. So dense that electrons are squeezed into the protons, forming neutrons.
The result, a neutron star, can stuff the mass of 1.4 Suns into an area 7 to 12 miles (11 to 20 kilometers) across.
A neutron star often sucks the life out of a companion, using its immense gravity to steal gas and dust from the nearby normal star. When this matter smacks into the surface of the neutron star, the radiation and rotational force of the star blast some of the material back into space, creating a stellar wind that races through space at 4.5 million miles (7.2 million kilometers) per hour.
And neutron stars are prone to occasional flare-ups, similar to solar flares on our Sun. But in a single flare lasting just a few hours, a neutron star can generate 100 times more energy than our Sun does in an entire year.
http://www.space.com/scienceastronomy/top_10_weird_list_7.html