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
- SUSY Q-ball
- B-ball, stable Q-balls with a large baryon number B. They may exist in neutron stars that have absorbed Q-ball(s).
- Abstract, Are Q-stars a serious threat for stellar-mass black hole candidates?, Miller J.C., Shahbaz T., Nolan L.A, 1997
- Abstract, No observational proof of the black-hole event-horizon, Marek A. Abramowicz, Wlodek Kluzniak, Jean-Pierre Lasota, 2002