NGC 4567 and NGC 4568 (nicknamed the Butterfly Galaxies or Siamese Twins) are a set of unbarred spiral galaxies about 60 million light-years away in the constellation Virgo. They were both discovered by William Herschel in 1784. They are part of the Virgo Cluster of galaxies.
These galaxies are in the process of colliding and merging with each other, as studies of their distributions of neutral and molecular hydrogen show, with the highest star-formation activity in the part where they overlap. However, the system is still in an early phase of interaction.
Four supernovae have been observed in the Butterfly Galaxies: SN 1990B (type Ib, mag. 16), SN 2004cc (type Ic, mag. 17.5), SN 2020fqv (type IIb, mag. 19), and SN 2023ijd (type II, mag. 16.8).
Naming controversy
The two galaxies were nicknamed "Siamese Twins" because they appear to be connected. On August 5, 2020, NASA announced that they would not use that nickname in an effort to avoid systemic discrimination in their terminology.
See also
Antennae Galaxies
Eyes Galaxies
Notes
References
External links
Kopernik Space Images, Spiral Galaxies NGC 4568 and NGC 4567 aka "The Siamese Twins" : Supernova 2004cc, George Normandin (29 June 2004) Skyhound, The Siamese Twins SIMBAD, VCC 1673 : NGC 4567 -- Galaxy in Pair of Galaxies SIMBAD, VCC 1676 : NGC 4568 -- Galaxy in Pair of Galaxies NED, VV 219 NED, NGC 4567 NED, NGC 4568
Virgo (constellation) Virgo Cluster 4567 42064 Interacting galaxies Unbarred spiral galaxies Overlapping galaxies