Why is mystery object Cygnus X-3 so bright? Astronomers may now have the answer
![Why is mystery object Cygnus X-3 so bright? Astronomers may now have the answer](https://cdn.mos.cms.futurecdn.net/Ss3TwWSLHRSs4D2dw7HMMP.jpg)
The X-ray-emitting binary system Cygnus X-3 features a massive star donating matter to a compact object, probably a black hole. That may explain its perplexing brightness.