Type I supernovae happen in close binary systems and do not show strong hydrogen emission lines. (astronomynotes.com)
Some short - duration GRBs may be the product of mergers between neutron stars (or neutron stars and black holes) in close binary systems (more from Insights Magazine and the movie). (members.nova.org)
In January an international team of astronomers confirmed that one of the largest black holes in the universe is paired with a much smaller partner nearby — the first definitive observation of black holes in a close binary system [subscription required]. (discovermagazine.com)