Right before a star dies, it throws off a great amount of gas. This is common in red giants. In the event of a Super Nova (which are rare) the sun`s core is crushed in the dense gravity after the massive explosion. These stars are very small, but still bright and it spins very fast. These are called Neutron stars (Pulsars). One good example is the Crab Nebula which exploded in 1054AD and was clearly visible with the naked eye. 1900 years later when technology allowed us to view this phenomenon, we pointed our radio telescopes at that point which emitted a great deal of "noise". This is common in Pulsars, and tells us that this noise comes from Neutron stars. In some cases after a Super Nova and the gravitational forces are overwhelming, it will crush the core and create a vast gravity well. Hence a black hole. Some stars just peter out and all there is left is a iron core. Light spectrum observing can also help us determine the age and type of star. As for knowing if a star is burned out, there are theories and the ability to calculate "red shift" that helps in how the stars live and die.

• RE: RE: stars - me - April 11, 2000 - 00:59 UTC