Arp objects

Source: Wikipedia. Pages: 37. Chapters: Atlas of Peculiar Galaxies, Messier 87, Centaurus A, Whirlpool Galaxy, Messier 82, Pinwheel Galaxy, Messier 32, NGC 3227, NGC 4631, Antennae Galaxies, NGC 1316, Messier 90, NGC 1569, NGC 5195, Messier 60, NGC 3226, NGC 4088, Arp 104, Messier 77, NGC 2608, Messier 49, Messier 66, Arp 220, NGC 1232, NGC 7252, NGC 4618, Mice Galaxies, NGC 1097, NGC 7318, NGC 4027, UGC 6945, IC 167, NGC 6946, NGC 520, Arp 276, NGC 772, NGC 3310, Tadpole Galaxy, Arp 299, Mayall's Object, NGC 7752 and NGC 7753, NGC 5679 Group, UGC 9618, NGC 2535, NGC 2536, NGC 5930, NGC 5579, NGC 2537, MCG+04-35-019, NGC 7320, NGC 145, NGC 5544, NGC 5820, NGC 5545, NGC 4194, NGC 5665, UGC 9425, NGC 1134, Arp 64, Arp 107, IC 4462, UGC 2320, UGC 1432, Arp 187, UGC 2140, Arp 272, Arp 87, Arp 178, Arp 297, Arp 47, Arp 177, Arp 173, Arp 240, Arp 117, Arp 42. Excerpt: The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institute of Technology. The primary goal of the catalog was to present photographs of examples of the different kinds of peculiar structures found among nearby galaxies. Arp realized that the reason why galaxies formed into spiral or elliptical shapes was not well understood. He perceived peculiar galaxies as small "experiments" that astronomers could use to understand the physical processes that distort spiral or elliptical galaxies. With this atlas, astronomers had a sample of peculiar galaxies that they could study in more detail. The atlas does not present a complete overview of every peculiar galaxy in the sky but instead provides examples of the different phenomena as observed in nearby galaxies. Because little was known at the time of publication about the physical processes that caused the different shapes, the galaxies in the atlas are sorted based on their appearance. Objects 1-101 are individual peculiar spiral galaxies or spiral galaxies that apparently have small companions. Objects 102-145 are elliptical and elliptical-like galaxies. Individual or groups of galaxies with neither elliptical nor spiral shapes are listed as objects 146-268. Objects 269-327 are double galaxies. Finally, objects that simply do not fit into any of the above categories are listed as objects 332-338. Most objects are best known by their other designations, but a few galaxies are best known by their Arp numbers (such as Arp 220). Today, the physical processes that lead to the peculiarities seen in the Arp atlas are now well understood. A large number of the objects are interacting galaxies, including M51 (Arp 85), Arp 220, and the Antennae Galaxies (NGC 4038/NGC 4039, or Arp 244). A few of the galaxies are simply dwarf galaxies that do not have enough mass to produce enough gravity