NGC 3923 is an elliptical galaxy found in Hydra, approximately 90 million light years away from Earth and spanning about 155,000 light years in diameter. It is an example of a shell galaxy, characterized by symmetrical shells of stars in its halo which are tens of thousands of light-years across. It is thought that the shells are formed when a big elliptical galaxy collides head-on with a smaller one, causing ripples of material to compress and spread outward, resulting in waves of star formation that produce the shells. Young stars are seen in the shells, making the theory consistent. However, there are also possibilities that off-center collisions can strip stars from a smaller galaxy, flinging them around a bigger galaxy, creating the shells, in a kind of galactic cannibalism. NGC 3923 has up to 42 symmetrical shells, the highest number of all known galaxies, but more subtle than those of other shell galaxies.
NGC 3923 is accompanied by seven dwarf elliptical galaxies within a 25 arcminute radius, all of them part of the same galaxy group.
At the top right of the image is visible NGC 3904, another elliptical Galaxy with a large halo. Notable among the other galaxies are the spiral galaxy PGC36882 in the top left of the image and the edge-on galaxy PGC37271 on the bottom, characterized by a pronounced dust lane across its disk. Additionally, dozen other galaxies can be observed in the field of view, as well as several faint galactic cirri, which are filamentary dust clouds that belong to our own Galaxy.
Takahashi CCA250 (250/f5) - ZWO 6200MM - L (1200m) R (90m) G (90m) B (90m) - AMT Observatory (
A.Lau/M.Lorenzi/T.Tse), Río Hurtado, Chile. Elaboration images M.Lorenzi.
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