Rotating compact stars with exotic matter
  We have constructed models of uniformly rotating compact stars including hyperons, Bose-Einstein condensates of antikaons and quarks. First order phase transitions from hadronic to antikaon condensed matter and then to quark matter are considered here. For the equation of state undergoing phase transitions to antikaon condensates, the third family of compact stars are found to exist in the fixed angular velocity sequences. However, the third family solution disappears when the compact stars rotate very fast. For this equation of state, the fixed baryon number supramassive sequence shows a second stable part after the unstable region but no back bending phenomenon. On the other hand, we observe that the rotation gives rise to a second maximum beyond the neutron star maximum for the equation of state involving phase transitions to both antikaon condensed and quark matter. In this case, the back bending phenomenon has been observed in the supramassive sequence as a consequence of the first order phase transition from $K^-$ condensed to quark matter. And the back bending segment contains stable configurations of neutron stars. 
Sarmistha Banik, Matthias Hanauske, Debades Bandyopadhyay and Walter   Greiner