The well-studied V404 Cygni, an X-ray binary hosting a low-mass black hole, is part of a wide hierarchical triple with a tertiary companion at least 3,500 astronomical units (AU) away from the inner binary, according to MIT astrophysicists. V404 Cygni. Image credit: Burdge et al., doi: 10.1038/s41586-024-08120-6. V404 Cygni is located about 7,800 light-years away in the constellation of Cygnus. This system first jumped to prominence during a nova...