Seyfert's Sextet (Hickson 79)

Hickson 79
Hickson 79: Seyfert's Sextet galaxy group in Serpens [567]


This group of galaxies was discovered on 17 June 1876 by the French astronomer Jean Marie Édouard Stephan. From 1866 to 1907 he was director of the observatory in Marseille and used the 31 inch Foucault reflector. He noted: «Excessively excessively faint; surrounds a very small star; appears to reach 2 other fainter ones.» John L. E. Dreyer added it in 1888 as NGC 6027 to his «New General Catalogue». [277, 313, 568]

In the late 1940s during an investication of faint galaxies made at the Barnard Observatory of Vanderbilt University the astronomer Carl Seyfert discovered that it was not a single galaxy, but an exceedingly compact group of six galaxies. Walter Baade suspected on the photographs with the 100 and 200 inch telescopes that one apparent member of the sextet was not a galaxy but simply a tidal tail stripped off of one of the other members and that the small spiral due to its abnormal size might not be a true member of the group. [569]

In 1959 the Russian astronomer Boris Vorontsov-Velyaminov published his «Atlas and Catalogue of Interacting Galaxies». This group of galaxies is referred as VV 115. [432]

The British-Canadian astronomer Paul Hickson presented in 1982 his systematic search for groups of galaxies on the photo plates of the Palomar Observatory Sky Survey (POSS) to the public. He counted five members in this group.

Physical Properties

This is a grouping of galaxies entangled in gravity that could bring them together to form one large elliptical galaxy. They are so tightly packed together that gravitational forces are ripping stars from them and distort their shapes. Unlike other interacting galaxies this group shows no evidence of characteristic blue regions of young star clusters. It may be that it is at the beginning of interaction, before much has happened.

The group resides 190 million light-years away and spans just 100'000 light-years, occupying less volume than our Milky Way galaxy. Each galaxy is about 35'000 light-years in diameter. The nearly edge-on spiral galaxy remains relatively undisturbed, except for the slight warp in its disk. The small face-on spiral with the prominent arms of gas and stars is a background galaxy almost five times farther away than the other four. [567]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
NameRA [hms]Dec [dms]mTypeDim [']Btot [mag]HRV [km/s]PA [°]
PGC 56575, NGC 6027, HICK 79C15 59 10.4+20 45 38C M.4 x .215.14413
PGC 56576, NGC 6027A, HICK 79A15 59 11.4+20 45 15C M.7 x .514.74197
PGC 56578, NGC 6027C, HICK 79D15 59 12.0+20 44 47C M.9 x .216.54482
PGC 56579, NGC 6027E, HICK 79B15 59 12.7+20 45 47C M.8 x .414.24095
PGC 56580, NGC 6027D, HICK 79E15 59 13.1+20 45 33C M.2 x .216.319813

Finder Chart

Seyfert' Sextet can be found in the head of the constellation Serpens. The best time for observation is in the months from March to September.

Chart Seyfert's Sextet (Hickson 79)
Seyfert's Sextet (Hickson 79) in constellation Serpens. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

More Objects Nearby (±25°)


144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); (2021-02-18)
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)
313«A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged» Dreyer, J. L. E. (1888); Memoirs of the Royal Astronomical Society. 49: 1–237; Bibcode:1888MmRAS..49....1D
432«The Atlas and Catalogue of Interacting Galaxies» B.A. Vorontsov-Velyaminov (Moscow 1959); (2021-09-25)
567Seyfert's Sextet: Four Colliding Galaxies, and two Bystanders; (2022-11-12)
568«Nébuleuses découvertes et observées à Marseille» Stephan, E.; Astronomische Nachrichten, volume 105, Issue 6, p.81, April 1883; DOI:10.1002/asna.18831050602; Bibcode:1883AN....105...81S
569«A Dense Group of Galaxies in Serpens» Carl K. Seyfert; Publications of the Astronomical Society of the Pacific, Volume 63, Number 371, 1951; DOI:10.1086/126319