Posting images of galaxies in Halton Arp's Atlas of Peculiar Galaxies (1966).
Automated account. Image curation, descriptions, typos, and most alt text by human astronomer @KellyLepo.
See posts for image credits and links to the original sources.
Gran Telescopio Canarias image of Arp 84, also known as NGC 5394 and NGC 5395.
This interacting pair is sometimes called the "Heron Galaxy". The larger spiral, NGC 5395 forms the body and wing of the heron and the smaller, two-armed NGC 5394 forms the neck, head, and beak of the bird.
Credit: GTC, IAC
Source: https://www.gtc.iac.es/multimedia/imageGallery.php
Kitt Peak image of Arp 78, also known as NGC 772.
One of NGC 772’s spiral arms is particularly prominent. This is likely due to gravitational interactions with its companion galaxy NGC 770, the small elliptical galaxy in the center near the top of the frame. The interactions left NGC 772's bottom arm elongated and asymmetrical.
Credit: KPNO, NOIRLab, NSF, AURA, A. Block
Source: https://noirlab.edu/public/images/noao-n772block/
Hubble Space Telescope image of Arp 25, also known as NGC 2276.
This face-on spiral galaxy looks lopsided, with its core offset to the upper left and a single spiral arm that is separated from the others. It is interacting with the nearby elliptical galaxy NGC 2300, just out of frame.
Credit: NASA, ESA, STScI, P. Sell
Source: https://science.nasa.gov/asset/hubble/ngc-2276/
Hubble image of Arp 148, also known as Mayall's Object.
The nickname comes from astronomer Nicholas Mayall, who first imaged the object in 1940 and noted it looked like a question mark.
The galaxy to the left likely crashed through the galaxy on the right, creating a ring and triggering a burst of star formation.
Credit: NASA, ESA, STScI, A. Evans, K. Noll, and J. Westphal
Source: https://science.nasa.gov/asset/hubble/hubble-interacting-galaxy-arp-148/
Legacy Surveys image of Arp 201, also known as UGC 224.
Arp 201 is an interacting galaxy pair.
Credit: Legacy Surveys, D. Lang, NERSC, Meli thev, Wikimedia Commons
Source: https://commons.wikimedia.org/wiki/File:Arp_201_legacy_dr10.jpg
SDSS image of Arp 82, also known as NGC 2535 and NGC 2536.
Simulations suggest the two galaxies are in the early stages of a merger. The pair already experienced one collision and are just about to collide again.
The larger galaxy's inner arms have evenly spaced "beads on a string" star clusters. This suggests the recent gravitational interactions created shocks that led to a burst of star formation.
Credit: SDSS
Source: https://www.legacysurvey.org/viewer?ra=122.8074&dec=25.2048&layer=sdss&zoom=13
Kitt Peak image of Arp 30, also known as NGC 6365.
Arp placed this in the category "Spiral galaxies - One heavy arm" in his original 1966 catalog. However, later higher-resolution images show this is actually a pair of interacting galaxies, with one galaxy viewed face-on and one viewed nearly edge-on, not one galaxy with a particularly beefy arm.
Credit: KPNO, NOIRLab, NSF, AURA, Friends' Central School, A. Block
Source: https://noirlab.edu/public/images/noao-n6365fcs1/
Hubble image of Arp 186, also known as NGC 1614.
NGC 1614 is likely the remnant of a tidal interaction and the resulting merger of two galaxies — a large spiral and a much smaller companion.
Credit: NASA, ESA, STScI
Source: https://science.nasa.gov/asset/hubble/hubble-interacting-galaxy-ngc-1614/
Kitt Peak National Observatory image of Arp 18, also known as NGC 4088.
NGC 4088 is an asymmetric spiral galaxy, located about 40 million light years away.
Credit: KPNO, NOIRLab, NSF, AURA, Bonnie Fisher, Mike Shade, Adam Block
Source: https://noirlab.edu/public/images/noao-n4088shade/
JWST NIRCam image of Arp 142, also known as NGC 2936 and NGC 2937, or the Penguin and the Egg.
The blue haze in the distorted spiral galaxy, elliptical galaxy, and the bridge connecting the two are stars. The red filaments are glowing dust. The edge-on galaxy at top right is in the foreground, significantly closer to us than the Penguin and the Egg.
Credit: NASA, ESA, CSA, STScI
Source: https://webbtelescope.org/contents/media/images/2024/124/01J06XYGEDEE86D1H9N5EJ9EG0
Kitt Peak image of Arp 94, also known as NGC 3226 and NGC 3227.
The large spiral galaxy, NGC 3227 is interacting with its elliptical galaxy companion, NGC 3226. Faint tidal streams of gas and dust link the pair, showing evidence of their mutual gravitational tugs.
Credit: KPNO,NOIRLab,NSF/AURA/Sid Leach and Wil Milan/Adam Block
Source: https://noirlab.edu/public/images/noao-n3227leach/