Dead stars sometimes shine again — and gravity itself may be responsible

[Admin]

Do dead stars glow? A strange gravitational phenomenon could be generating enormous amounts of light around neutron stars, new research suggests.

Dead stars sometimes shine again — and gravity itself may be responsible : Read more

 

[Unclear Engineer]

I am not seeing the math for the statement "Their gravity is strong enough to pull light itself into orbits around the star and accelerate nearby objects to nearly the speed of light." [emphasis added] The escape velocity from a neutron star is less than the speed of light, even at its surface, and the speed of a satellite must be less than escape velocity.

Using Newtonian gravity, the speed of a satellite orbiting a neutron star with 2 x the mass of the Sun at the speed of light would need to be at an altitude of only 3 km from the center of the neutron star. But, I think neutron stars have larger radii.

But, I am not familiar with the relativistic calculations for the orbital velocity vs radius, in particular, the effects of issues like frame-dragging. With the extreme rotational speeds of neutron stars, I am guessing that frame dragging near their surfaces is not insignificant.

Does anybody on this forum understand how light could "orbit" a neutron star in a closed orbit? If so, please give me some explanation.