Q star
A Q-Star, also known as a grey hole, is a hypothetical type of a compact, heavy neutron star with an exotic state of matter. Such a star can be smaller than the progenitor star's Schwarzschild radius and have a gravitational pull so strong that some, but not all light, cannot escape. The Q stands for a conserved particle number. A Q-Star may be mistaken for a stellar black hole.Types of Q-stars
