NGC 5189 (Gum 47, IC 4274, nicknamed Spiral Planetary Nebula) is a planetary nebula in the constellationMusca. It was discovered by James Dunlop on 1 July 1826, who catalogued it as Δ252.[1] For many years, well into the 1960s, it was thought to be a bright emission nebula. It was Karl Gordon Henize in 1967 who first described NGC 5189 as quasi-planetary based on its spectral emissions.
Seen through the telescope it seems to have an S shape, reminiscent of a barred spiral galaxy. The S shape, together with point-symmetric knots in the nebula, have for a long time hinted to astronomers that a binary central star is present.[2]
The Hubble Space Telescope imaging analysis showed that this S shape structure is indeed two dense low-ionization regions: one moving toward the north-east and another one moving toward the south-west of the nebula,[3] which could be a result of a recent outburst from the central star. Observations with the Southern African Large Telescope have finally found a white dwarf companion in a 4.04 day orbit around the rare low-mass Wolf-Rayet type central star of NGC 5189.[4] NGC 5189 is estimated to be 546 parsecs[5] or 1,780 light years away from Earth. Other measurements have yielded results up to 900 parsecs (~3000 light-years).[6]
^Phillips, J. P.; Reay, N. K. (1983). "Ansae and the precession of central stars in planetary nebulae - The cases of NGC 5189 and NGC 6826". Astronomy and Astrophysics. 117: 33–37. Bibcode:1983A&A...117...33P.
