Seyfert's Sextet

Seyfert's Sextet is a group of galaxies about 190 million light-years away^[2] in the constellation Serpens. The group appears to contain six members, but one of the galaxies, NGC 6027d, is a background object (700 million light years behind the group) and another "galaxy," NGC 6027e, is actually a part of the tail from galaxy NGC 6027. The gravitational interaction among these galaxies should continue for hundreds of millions of years. Ultimately, the galaxies will merge to form a single giant elliptical galaxy.

Seyfert's Sextet
A Hubble Space Telescope (HST) image of Seyfert's Sextet. All galaxies (left to right): NGC 6027e, NGC 6027, NGC 6027d (below NGC 6027), NGC 6027c (bottommost galaxy), NGC 6027a (Lenticular galaxy with a dust lane above NGC 6027c), NGC 6027b (above NGC 6027a). Credit: HST/NASA/ESA.
Observation data (Epoch J2000)
Constellation(s)	Serpens
Right ascension	15h 59m 11.9s[1]
Declination	+20° 45′ 31″[1]
Brightest member	NGC 6027
Number of galaxies	6[1]
Other designations
Serpens Sextet, HCG 79, UGC 10116, VV 115, VII Zw 631[1]

Discovery

French astronomer Édouard Stephan discovered NGC 6027 on 20 March 1882, but he was unable to resolve the individual galaxies in the group.^[3] The group members were discovered by Carl Keenan Seyfert using photographic plates made at the Barnard Observatory of Vanderbilt University. When these results were first published in 1951, this group was the most compact group ever identified.^[4]

Members

Members of Seyfert's Sextet

Name	Type	Distance from Sun (million ly)	Magnitude
NGC 6027	S0 pec.	~190	+14.7
NGC 6027a	Sa pec.	~190	+15.4
NGC 6027b	S0 pec.	~190	+15.4
NGC 6027c	SB(S)c	~190	+16
NGC 6027d	SB(S)bc pec.	~877[5]	+15.6
NGC 6027e	Tidal Tail.	~190	+16.5

See also

• Wild's Triplet
• Zwicky's Triplet
• Robert's Quartet
• Stephan's Quintet and NGC 7331 Group (also known as the Deer Lick Group); about half a degree northeast of Stephan's Quintet
• Copeland Septet