Arp’s Peculiar Galaxies
Page 16 of 18
Arp observations 151-160 of 171 total to date.
| Thumbnail | Title/link | Arp Category | Date Observed | Observer Description |
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Arp 294 / NGC 3786 / NGC 3788 | Double or multiple galaxies with long filaments | 2026-02-27 23:58:00 | Arp's remarks say, with typical economy, "Peculiar filaments". That presumably refers to the stellar stream heading NNW (left) from NGC 3788. Subsequent to my capture, I've found long exposure astrophotographs showing a circular stellar stream looping behind the south side of NGC 3786. That's barely hinted at in Arp's image, and mine. . |
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Arp 297 / NGC 5754 – 5752 | Double or multiple galaxies with long filaments | 2025-06-12 00:39:00 | Captured on a full moon night with even a little smoke, which improved the later it got. I believe it's important to capture the feature Arp cared the most about, and in this case its the tidal filament extending from the bottom of NGC 5754 and looping up and to the right connecting it to NGC 5752. The additional filaments out of NGC 5755 probably increased the peculiarity. While conditions were far from ideal, the image was building slowly and I could just start to see the filaments at about 50 minutes. In the conditons, I'm pleased I can see it at all. |
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Arp 298 / NGC 7469 with IC 5283 | Unclassified double galaxies | 2024-10-28 22:26:00 | This is one of the more unusual Arp Catalog entires: two galaxies in close proximity. The only suggestion that they are interacting is a slight twisting of an arm in the small galaxy (IC 5283) towards NGC 7469, an elongated core, and a slight suggestion of a dust trail. NGC 7469 appears to my eyes as being type S0 - aka Lenticular -- intermediate between a spiral and elliptical. There remain clear spiral structure in the core, which is fading in the outer envelope.. |
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Arp 299 / NGC 3690 / IC 694 | Unclassified double galaxies | 2024-05-24 23:07:00 | Another surprisingly good capture given a waning moon just a couple of days past full. Luckily aiming directly away. These galaxies are astonishing. Two appear so well integrated that they have a single NGC number instead of two consecutive, or, as you see often an A/B. They both seemed to be irregular barred galaxies that, by this point, have merged galactic centers. Even Arp seems resigned to the fact in his remarks: "Bright internal knots." The dwarf IC 694 seems to be sucked in from the bottom of the image as well. |
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Arp 304 / NGC 1241 and 1242 | Unclassified double galaxies | 2025-11-22 22:28:00 | Arp 304 consists of two galaxies NGC 1241 and NGC 1242, left to right and a double star to the southeast, NGC 1243. The two galaxies were first seen by William Herschel. John Herschel, unable to see 1242 recorded the double star NGC 1243. Dreyer saw all three but recorded the double star as a nebula. Arp didn't seem too fussed as he left no remarks. The only peculiar structure seems to be a slightly enlarged arm on NGC 1241 pulled away in the direction of NGC 1242. |
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Arp 307 / NGC 2874-2873-2872 | Galaxies with concentric rings or Double Galaxies(?) | 2025-01-26 20:10:00 | This is a lovely cluster, but hard to interpret. Sources don't agree on how Arp categorized it: Kanape and Webb list it as "Double Galaxies" The AL list has the category as having "concentric rings" presumably referring to the lenticular galaxy NGC 2974 alone. The Cal Tech website doesn't list its category. Anyway, judging from the halos around the galaxies, which are most clear in the inverted images (either mine or Arp's) it looks to me that 2974 and 2972 are interacting, and it's ambiguous if 2973 has joined the fun. That said, Arp left a cryptic set of remarks: "Position between pair. Possibly not interacting. " It's ambiguous whether he's referring to 2972 (the medium sized elliptical) or 2973 (the small spiral). |
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Arp 308 / Abell 194 | Unclassified double galaxies | 2025-01-23 19:23:00 | This was a "2 for" - a second Arp galaxy group within the same FOV as "Minkowski's Object" (Arp 133). It consists of two interacting galaxies (L to R): NGC 545, a lenticular galaxy, and NGC 547, an elliptical galaxy. During capture I noticed an extended halo from NGC 545 up and to the right towards Arp 133 (southeast given that N is left in these images), which became more pronounced after processing. Arp, himself, doesn't mention it in comments, saying: "Close ellipticals. Position of central galaxy (NGC 541)". |
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Arp 310 / IC 1259 | Unclassified double galaxies | 2025-08-27 23:58:00 | Arp describes this object as "Very close E galaxies". Famously brief, I'm guessing he's interpreting the 3 nuclei as each belonging to separate galaxies, though I would venture a more common description today might be, "3 merged -- or merging -- galaxies where the nuclei are still distinct". Note Arp remarks further: " Picture is 10X [magnification] of following (No. 311) area". |
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Arp 311 / IC 1258, 1259, 1260 | Unclassified double galaxies | 2025-08-27 23:58:00 | Arp is positively fulsome in his description here: "Same as 310, but shows surrounding field and group. Picture is 4X of preceding (No. 310) area". The two larger galaxies (IC 1258 and 59) certainly do appear to be exchanging mass. The connection to IC 1260 is a little more tenuous but still suggested. |
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Arp 315 / NGC 2830 / NGC 2831 / NGC 2832 | Groups of galaxies | 2026-03-02 22:17:00 | Arp's criteria for selecting galaxy clusters are often opaque, and this is a good example. Here his remarks opine: "Companion E[lliptical] is quite compact". Presumably, this means he found the tightness of this grouping peculiar. NGC 2832 is the dominant E galaxy, NGC 2830 is the spiral galaxy to the upper right, and presumably NGC 2831 is the "compact" companion. These three galaxies are at the center of a much larger cluster, designated Abell 779 with at least 30 members. The original Abell cluster list was based on the 1958 Palomar Sky Survey, which didn't get terribly "deep" by modern standards. Today, it's tough to find an "official" count because people count galaxies in their images which invariably show many more galaxies than did Abell's 1958 POSS images. I've seen estimates between 32 and 80. Of course, many of the additional galaxies are background galaxies and not necessarily part of a real "cluster". |