Siamese Twins (NGC 4567/8)

NGC 4567
NGC 4567: Siamese Twins in Virgo; 500 mm Cassegrain 5800 mm f/11.4; SBIG STL11K; 135+20+20+20 min LRGB; Bernese Highlands; © 2005 Radek Chromik


The two galaxies were discovered on 15th March 1784 by William Herschel. As for most of his discoveries he was using his 18.7 inch reflecting telescope with 20 feet focal length. He cataloged them as IV 8 and IV 9 (class IV = planetary nebulae, stars with burs, with milky chevelure, with short rays, remarkable shapes, etc.) He described as «a double nebula. The chevelure run into each other. close. not very faint.» In 1888 Dreyer added those two objects as NGC 4567 and NGC 4568 to his famous catalog. [463]

Physical Properties

The pair of galaxies is also known as butterfly galaxies because they look like such a flapping of wings. These are galaxies that are circa 6 kpc close together and it has been discovered, that they show a warmer and denser gas tracer in the overlapping region, which indicates an early stage of interaction. The interaction has not yet destroyed the inner spiral structures of NGC 4568 and NGC 4567, but does affect the outer stellar disk. [611, 612]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
NameRADecTypebMagvMagB-VSBDimPAzD(z)MDDreyer DescriptionIdentification, Remarks
NGC 456412 36 26.9+11 26 23Gx (E6) × 1.5470.00380916.0916.120pB, S, lE, psbMUGC 7773, MCG 2-32-150, CGCG 70-186, VCC 1664
NGC 456712 36 32.7+11 15 28Gx (Sbc) × 2.2850.00749531.6625.550vF, L, np of D neb, pos 160° ±UGC 7777, MCG 2-32-151, CGCG 70-189, IRAS 12340+1130, VCC 1673, VV 219, KCPG 347A, Siamese twins
NGC 456812 36 34.2+11 14 19Gx (Sbc)11.710.80.913.14.6 × 2.2230.00752231.7720.930vF, L, sf of D neb, pos 160° ±UGC 7776, MCG 2-32-152, CGCG 70-188, IRAS 12340+1130, VCC 1676, VV 219, KCPG 347B, Siamese twins
IC 357812 36 39.5+11 06 05Gx (Sc) × 0.31350.0023239.81S, E 125°UGC 7782, MCG 2-32-153, CGCG 70-190, VCC 1684

Finder Chart

The galaxy pair can be found in the Virgo constellation in the Virgo cluster. Connect the stars Vindemiatrix (ε Virginis, 2.8 mag) and Denebola (β Leonis, 2.1 mag). Position the Telrad in about the first third so that the middle Telrad circle comes below the connecting line and the 4.9 mag star ρ Virginis comes between the outer circles. The pair of galaxies is located about half a degree southwest of Messier 58. Not far from there is a pair of stars of about the same brightness of about 12th magnitude.

Finder Chart Siamese Twins (NGC 4567/8)
Siamese Twins (NGC 4567/8) in constellation Virgo. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

NGC 4567 + NGC 4568
NGC 4567 + NGC 4568: Pencil drawing; 14" PWO-Dobson f/4.6, TV-Radian 8 mm, 200x, 0.3°, D: 6.0, air: moderate-quiet; Honegg 1460m; © 31. 5. 2003, 01:45 Eduard von Bergen

350 mm aperture: With 11.3 mag and 10.8 mag the two glaxies can already be found in smaller telescopes. Both have a bright core and are elliptical in shape. They appear to be touching at the ends. However, the latter can only be seen with certainty with a medium-sized aperture. [192]

14" PWO-Dobson, F:4.6 / TV-Radian 8mm, 200x, 0.3°
Eduard von Bergen

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