Can we really rule out the existence of antistars?
  The existence of large domains of antimatter is still an open question. Some space mission and experiments in the near future are expected to give reasonable answer to that question. Meanwhile, we can try to search for other signatures of the presence of antimatter. This paper presents a discussion about possible effects of the close encounter of stars and antistars. It is known that the accretion power can be higher in presence of antimatter, because of high-energy photons generated in annihilation, which result in a smaller radiation pressure. Therefore, the Eddington luminosity can reach higher values. Calculations of the gamma-ray flux above 100 MeV, and comparison with recent data from satellites, show a good agreement for certain sources. So, let's play some science-fiction! 
Luigi Foschini