Mice Galaxies (NGC 4676 A/B)

NGC 4676: Galaxy in Coma Berenices. North is right; 500 mm Cassegrain 3625 mm f/7.2, SBIG STL11K; 180-60-60-60 min LRGB; Bernese Highlands; © 2011 Radek Chromik


These two interacting Galaxies were first seen by William Herschel on 13th March 1785. As usual he was observing with his large his 18.7 inch reflecting telescope of 20 feet focal length, located in Slough, England. He cataloged it as II 326 and noted: «faint, much extended in the direction of the meridian.» [463] His son John cataloged it later as h 1425 (GC 3207) and thought he had seen two nucleus. He noted: «extremely faint, query if not bicentral». [466] John L. E. Dreyer added it 1888 as NGC 4676 in his «New General Catalogue». [313]

On 3rd March 1892 the Austrian astronomer Rudolf Spitaler observed the same galaxy with the 27 inch refractor at Wien University Observatory. He saw two objects which were later added as IC 819 and IC 820 by Dreyer in his «Index Catalogue». He described both as «double nebula, connected, very faint, very small, south following, one brighter». [314] Because John Herschel described the nebula as having two nuclei and Spitaler listed them as two individual objects, they ended up as duplicate entries of NGC 4676 by mistake.

In Halton Arp's 1966 «Atlas of Peculiar Galaxies», the two interacting galaxies are listed as Arp 242 in the group #233-256 with «appearance of fission». [199]

NGC 4676: Image taken by Hubble Space Telescope in 2002 with blue, orange and near-infrared filters. © ESA/Hubble & NASA [476]

Physical Properties

The distance to NGC 4676 A/B is given as 102 Mpc (circa 331 million light years). [145] These are two nearly identical spiral galaxies approximately 160 million years after their closest encounter. Gravitational forces have deformed their spirals into long, stretched tidal tails, giving the nickname «The Mice» for this interacting pair of galaxies. The long, stretched arm is actually curved. We see it edge-on why it appears straight. Simulations show that the pair will eventually merge and form a large elliptical galaxy. The stars, gas and luinous clusters of stars in the tidal tails will either fall into the merged galaxies or remain in a orbit in the halo. Our own Milky Way will probably look similar when it collides with our neighbour the Andromeda Galaxy (M 31) in several billion years from now. [476]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
NameRADecTypebMagvMagB-VSBDimPAzD(z)MDDreyer DescriptionIdentification, Remarks
NGC 4676 A12 46 10.1+30 43 57Gx (SB0-a)14.413.50.913.21.4 × 0.600.02205993.18vF, pmE, ? biNIC 819, UGC 7938, MCG 5-30-76, CGCG 159-72, VV 224, Arp 242, DFOT 59, KCPG 355A, The Mice
NGC 4676 B12 46 11.2+30 43 21Gx (S0-a)14.713.80.914.32.2 × 0.820.02203993.09vF, pmE, ? biNIC 820, UGC 7939, MCG 5-30-77, CGCG 159-72, IRAS 12437+3059, KCPG 355B, Arp 242, VV 224, The Mice
IC 81912 46 10.1+30 43 57dup14.413.50.913.21.4 × 0.600.02205993.18D neb, conn, vF, vS, sf one brighterNGC 4676A, UGC 7938, MCG 5-30-76, CGCG 159-72, VV 224, Arp 242, DFOT 59, KCPG 355A, The Mice
IC 82012 46 11.2+30 43 21dup14.713.80.914.32.2 × 0.820.02203993.09D neb, conn, vF, vS, sf one brighterNGC 4676B, UGC 7939, MCG 5-30-77, CGCG 159-22, IRAS 12437+3059, KCPG 355B, Arp 242, VV 224, The Mice

Finder Chart

The pair of galaxies can be found in the constellation Coma Berenices. Best observation time is in the months December through July.

Finder Chart Mice Galaxies (NGC 4676 A/B)
Mice Galaxies (NGC 4676 A/B) in constellation Coma Berenices. 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

Description pending ...

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