NGC 4567/8, Siamese Twins

Object Description

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 March 15, 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]

The pair of galaxies is also known as butterfly galaxies because they look like such a flapping of wings. These are galaxies that are close together, but they do not influence each other. The Siamese twins are therefore no ordinary pair of galaxies. They should interact with each other, but that's exactly what you don't notice. A hitherto scientific inconsistency, which still needs to be clarified. [192]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
NameRA [hms]Dec [dms]mTypeDim [']Btot [mag]HRV [km/s]PA [°]
NGC 456412 36 26.9+11 26 21E3.2 x 1.812.0111947
NGC 456712 36 32.8+11 15 31S M3.1 x 2.212.1226685
NGC 456812 36 34.7+11 14 15S M4.6 x 2.211.7225523
IC 357812 36 39.5+11 06 12S.9 x .315.1135

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.

Chart NGC 4567
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [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, L: mittelmässig-ruhig; 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

References

144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); cdsarc.unistra.fr/viz-bin/cat/VII/119 (2021-02-18)
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
192Deep-Sky Guide; fernrohr.ch/1d_deep-sky-guide.html (2020-12-25)
463«Catalogue of one thousand new nebulae and clusters of stars» William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1786; DOI:10.1098/rstl.1786.0027