They are rotating nearly fast enough to break apart.
Straight lines are the shortest distance between two points.
Describe the similarities and differences between radio pulsars and X-ray pulsars. Both radio pulsars and X-ray pulsars must be rotating, magnetic neutron stars. X-ray pulsars must therefore be in binary systems to have a supply of mass from the companion star. Radio pulsars are usually single and if they are in a binary, they cannot be accreting. Describe the observational evidence that astronomers have discovered black holes orbiting norma l stars in binary systems.