NGC 5189, Musca

An object, believed for many years to be an emission nebula, it was re-characterised as a quasi-planetary nebula in the 1960s based on its spectral emissions. Its appearance is atypical of planetary nebulae hence the "quasi-" prefix to its identification.  The unusual appearance provided a hint that a binary star system was present at the centre, which was recently confirmed - a rare low-mass Wolf-Rayet primary and white-dwarf secondary in a 4 day orbit.  Distance is estimated to be in the region of 1800 ly.