Galaxy chains are fascinating to me. This poster captures my favorite ones. There is not a precise definition of a galaxy “chain”. Similar to Dr. Arp’s definition, I consider a galaxy chain to be a visually striking, mostly linear alignment of 4 or more galaxies, preferably with some visible disturbance to confirm that they are indeed related instead of just visually aligned. The objects in the poster are all distant, ranging from 300 to 800 million light years away, although the galaxies within each object are usually at the same distance.
The big question raised by this poster is whether the linear nature of a galaxy chain is simply a chance occurrence from our viewing perspective, a “happy accident”, or is there something about the nature of galaxy interactions that causes them to align in a linear fashion? Dr. Arp observed that aligned groups of 4 or more galaxies occur just as often as unaligned groups, which would favor the thesis that there is a driving mechanism behind the linear alignment and that it is not just random. But based on my experience with these groups, I think the chain alignments are simply random. However, I have no quantitative data on which to base my belief.
If you would like to read more about any of these objects, each of the objects in the poster has previously been uploaded and described individually on Astrobin. They all reside in my
Astrobin Galaxy Chains Collection.
If you would like to access all my DSO compilation posters, please click
here.
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