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Arp Bot 🤖

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.

Arp Bot 🤖ArpBot
2025-06-14

Hubble image of Arp 87, also known as NGC 3808 and NGC 3808A.

NGC 3808 (right) is a nearly face-on spiral galaxy with a bright ring of star formation and two spiral arms. It is interacting with its companion NGC 3808A (left). NGC 3808A is seen edge-on and is surrounded by a ring of stars and gas perpendicular to the plane of its disk, making it a polar ring galaxy.

Credit: NASA, ESA, and the Hubble Heritage Team
Source: science.nasa.gov/asset/hubble/

A pair of interacting galaxies. On the right is a nearly face-on spiral. It has a small, bright central core, surrounded by a haze of yellow stars. Surrounding this is a ring of blue stars, dotted by blue star clusters. Two wide spiral arms emerge from the ring, crossed by dark brown dust lanes. They fan out, almost connecting back to the main body of the galaxy. A line of blue star clusters begins at the left spiral arm and arcs around the body of the galaxy. The left arm extends out connecting to its companion galaxy at left. The left galaxy is an edge-on disk, seen as a wide, angled line of yellowish stars. A stream of blue stars, star clusters, and gas appears to come from its companion's spiral arm and wrap one and a half times around the disk galaxy. A third galaxy, a smaller edge-on spiral, is seen to the left of the disk galaxy. The black background of space is dotted with a few foreground stars and tiny background galaxies.
Arp Bot 🤖ArpBot
2025-06-13

JWST MIRI image of Arp 142, also known as NGC 2936 and NGC 2937, or the Penguin and the Egg.

At left, the Egg appears as a small teal oval with gauzy layers, showing the oldest stars in the elliptical galaxy, which has lost or used up most of its gas and dust. At right, the Penguin’s shows gas and dust that has been distorted and stretched, as well as soot-like dust in blue.

Credit: NASA, ESA, CSA, STScI
Source: webbtelescope.org/contents/med

Two interacting galaxies known as Arp 142 in a horizontal image taken in mid-infrared light. At left is NGC 2937, an elliptical galaxy that looks like a tiny teal oval and is nicknamed the Egg. At right is NGC 2936, a distorted spiral galaxy nicknamed the Penguin, which is significantly larger. A beak-like region points toward the Egg, but lies far above it. Where the eye would be is an opaque, almost washed-out pink spiral. This galaxy’s distorted pink, purple, and blue arms create the bird’s beak, back, and tail. The tail, which is closer to the Egg, is wide and layered, like a beta fish’s tail. The Penguin and the Egg appear very separate. The galaxy at top right, PGC 1237172, is barely visible. A brighter slightly larger blue foreground star that is over top of this galaxy has tiny diffraction spikes. Throughout the image are tiny galaxies in bright reds, greens, and blues. The background of space is black.
Arp Bot 🤖ArpBot
2025-06-13

Hubble image of Arp 200, also known as NGC 1134.

NGC 1134 is likely interacting with its small companion, seen to the lower right, producing streamers of stars that trail off to the right.

Credit: NASA, ESA, STScI, Julianne Dalcanton, Meli thev, Wikimedia Commons
Source: commons.wikimedia.org/wiki/Fil

A greyscale image of a face-on spiral galaxy. The faint galaxy has a bright core, a small oval-shaped ring, and two loose spiral arms that emerge from the ring and wind counterclockwise around the galaxy. The arms are crossed by dark dust lanes and dotted with bright star clusters. At the bottom right edge of the galaxy is a smaller elliptical galaxy, seen as a bright dot surrounded by an oval-shaped haze. Faint, hazy, lines of stars appear from the point where the two galaxies overlap and stream off diagonally, down and to the right. The image has a noticeable amount of detector noise which has not been removed.
Arp Bot 🤖ArpBot
2025-06-12

Image of Arp 116, also known as M60 and NGC 4647, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Elliptical galaxies - Close to and perturbing spiral galaxies. M60 is a giant elliptical galaxy. The smaller spiral NGC 4647 is about the size of our galaxy, the Milky Way. While it is not obvious, the two galaxies are just beginning to interact.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black and white image of a large elliptical galaxy and a smaller face-on spiral galaxy. The elliptical galaxy is in the lower right portion of the frame. It appears as a featureless, oval-shaped blob surrounded by a haze of stars. Above and to its left is its companion, a smaller face-on spiral galaxy. Its somewhat poorly defined spiral arms curve around its bright center. The arms are dotted with bright stars and star clusters and are crossed by a series of filamentary dust lanes. Many white dots, which are stars, are seen on the black background.
Arp Bot 🤖ArpBot
2025-06-11

Hubble image of Arp 302, also known as UGC 9618 or VV 340.

Arp 302 consists of a pair of very gas-rich spiral galaxies in the early stages of an interaction.

This image is part of a collection of 59 images of merging galaxies taken by the Hubble Space Telescope and released for its 18th anniversary in April 2008.

Credit: NASA, ESA, STScI, A. Evans
Source: science.nasa.gov/asset/hubble/

A pair of spiral galaxies. The upper galaxy is seen face-on. It has a bright center and short bar structure that transitions into a series of loosely-wound spiral arms, looking something like a cinnamon roll. The arms are dotted with blue star clusters and crossed by darker dust filaments. The lower galaxy is seen edge on. It has a somewhat puffy disk, seen as a wide, almost vertical, yellow line. Running down the middle is a dark dust lane with a few blue star clusters peaking out. In the middle of the frame, where the two galaxies appear to touch, is a bright foreground star with four diffraction spikes. Other distant galaxies and stars fill the black background of space.
Arp Bot 🤖ArpBot
2025-06-11

NuStar image of Arp 299, also known as NGC 3690.

This X-ray image from NuSTAR shows an active supermassive black hole in one of the galaxies in the interacting galaxy pair Arp 299. The other galaxy lacks such an active black hole and is not seen in this image.

Credit: NASA, JPL-Caltech, GSFC
Source: nustar.caltech.edu/image/nusta

A blurry, abstract image with blobs of white, pink, blue and yellow colors. The brightest area is a white blob to the lower right.
Arp Bot 🤖ArpBot
2025-06-10

JWST NIRCam and MIRI image of Arp 142, also known as NGC 2936, NGC 2937, and UGC 5130, or the Penguin and the Egg.

The Penguin is a spiral galaxy whose shape has been distorted by the gravity of the elliptical Egg galaxy. The two are about 100,000 light-years apart and completed a close pass between 25 and 75 million years ago.

Credit: NASA, ESA, CSA, STScI
Source: webbtelescope.org/contents/med

Arp 142, two interacting galaxies, observed in near- and mid-infrared light. At left is NGC 2937, nicknamed the Egg. Its center is brighter and whiter. There are six diffraction spikes atop its gauzy blue layers. At right is NGC 2936, nicknamed the Penguin. Its beak-like region points toward and above the Egg. Where the eye would be is a small, opaque yellow spiral. The Penguin’s distorted arms and orange dust lanes from the bird’s beak, back, and tail. The tail is wide and layered, like a beta fish’s tail. A semi-transparent blue hue traces the Penguin and extends from the galaxy, creating an upside-down U over top of both galaxies. At top right is another galaxy seen from the side, pointing roughly at a 45-degree angle. It is largely light blue. Its length appears approximately as long as the Egg’s height. One foreground star with large, bright blue diffraction spikes appears over top of the galaxy and another near it. The entire black background is filled with tiny, extremely distant galaxies.
Arp Bot 🤖ArpBot
2025-06-10

Hubble and Pan-STARRS image of Arp 6, also known as NGC 2537 or the Bear’s Paw Galaxy.

NGC 2537's horseshoe structure may be the result of a shockwave from a nuclear starburst.

In this image, the luminosity comes from Hubble ACS/WFC observations, and color comes from PanSTARRS.

Credit: NASA, ESA, STScI, J. Dalcanton, Judy Schmidt, PanSTARRS
Source: flickr.com/photos/geckzilla/33

A galaxy with a line-like nucleus and a horseshoe-shaped arc above it. The horseshoe points down, and the nucleus is in the center of the arc. It looks like an upside down power symbol, ⏻. The nucleus and horseshoe are dotted with bright blue star clusters and dark dust lanes.
Arp Bot 🤖ArpBot
2025-06-09

Hubble Space Telescope image of Arp 3.

Arp 3 is a low surface brightness spiral galaxy the constellation Aquarius.

Credit: NASA, ESA, STScI, Julianne Dalcanton, Meli thev, Wikimedia Commons
Source: commons.wikimedia.org/wiki/Fil

A greyscale image of a spiral galaxy. The faint galaxy has a central bar and loose spiral arms that are not very well defined, which arc clockwise around the bar. The arms are dotted with bright star clusters.
Arp Bot 🤖ArpBot
2025-06-09

Spitzer image of Arp 16, also known as M66.

In this infrared image of M66 from the Spitzer Infrared Nearby Galaxy Survey (SINGS), we see a stark contrast between the blue core and bar with a concentration of blue older stars, and the pink bar ends and spiral arms that show dust heated by actively forming stars.

Credit: NASA/JPL-Caltech/R. Kennicutt (University of Arizona) and the SINGS Team
Source: spitzer.caltech.edu/image/sig0

A nearly face-on barred spiral galaxy anchored by its central region, which has a bright blue central dot surrounded by a lighter diagonal blue bar structure made of a haze of stars. Two distinct spiny pink spiral arms start at the end of the bar, rotating clockwise, and forming an S-shape.
Arp Bot 🤖ArpBot
2025-06-08

Image of Arp 202, also known as NGC 2719 and NGC 2719A, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Amorphous galaxies - Material ejected from nuclei. This pair of galaxies, an edge-on disk galaxy near the bottom of the frame and a smaller irregularly shaped galaxy above it, had a recent interaction which likely severely perturbed both galaxies.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black and white image of two galaxies. Both are overexposed, so that there is no detail apparent in the interiors of the galaxies. At the center of the frame, running diagonally from lower right to upper left is a disk galaxy seen edge-on. To the left, aligned with the bottom edge of the disk galaxy, is a second smaller galaxy that is irregular but roughly circular. A faint line extends upwards from where the two galaxies meet. A few white dots, which are stars, are seen on the black background.
Arp Bot 🤖ArpBot
2025-06-08

Image of Arp 302, also known as UGC 9618 or VV 340, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Double and multiple galaxies - Unclassified objects. Arp 302 consists of a pair of very gas-rich spiral galaxies in the early stages of an interaction.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black and white image of a pair of spiral galaxies. The lower galaxy is seen face-on. It has a bright center that transitions into a series of loosely-wound spiral arms, looking something like a cinnamon roll. The arms are dotted with star clusters . The upper galaxy is seen edge on. It has a somewhat puffy disk, seen as a wide, vertical line. Together, the two galaxies look like an exclamation point. In the middle of the frame, where the two galaxies appear to touch, is a bright foreground star seen as a large dot. A few white dots, which are stars, are seen on the black background.
Arp Bot 🤖ArpBot
2025-06-07

Image of Arp 24, also known as NGC 3445, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Spiral galaxies - One-armed. NGC 3445 has one fan-like spiral arm that is dotted with star-forming regions. It is connected to its companion galaxy, seen nearly edge-on to the left, by a weak bridge. The two galaxies likely had a recent encounter.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black and white image of a spiral galaxy and its smaller companion. The frame is dominated by the large spiral galaxy. Its one spiral arm begins at about 12 o'clock and curves clockwise around the galaxy, completing a full circle. The arm is unusually thick, fanning out with many bright star clusters. Above the spiral is a smaller galaxy, seen almost edge-on. It appears as an elongated oval. The long axis of the oval is almost vertical. Connecting the two galaxies is a faint bridge of gas and stars. A few smaller background galaxies dot the black background of space. There is a bright foreground star, seen as a large dot with four diffraction spikes, in the upper right corner of the frame.
Arp Bot 🤖ArpBot
2025-06-07

Hubble image of Arp 219, also known as UGC 2812.

Arp 219 appears in several catalogs of ring galaxies. The ring, made of tidal tails of material that wrap around the galaxy, was likely formed through interactions with a companion galaxy.

In this image, the luminosity comes from Hubble ACS/WFC observations, and color comes from PanSTARRS.

Credit: NASA, ESA, STScI, J. Dalcanton, Judy Schmidt, PanSTARRS
Source: flickr.com/photos/geckzilla/46

A distorted galaxy with looping tidal tails. In the center of the frame is a galaxy with a bright yellow center. A dark brown dust lane divides the bright center of the galaxy in two. It's hard to tell if this dust is blocking a continuous bright area or if there are two distinct nuclei. The disk of the galaxy surrounds the center, probably seen nearly edge-on, made of a haze of older yellow stars. At the left and right edges of the disk are blue clusters of younger stars. One stream of gas and stars, a tidal tail, starts at the left edge of the disk, loops under the galaxy, and connects with the bottom right edge of the disk. A second stream of gas begins at the top right edge of the disk, loops over the galaxy, and then connects to the top left edge of the disk. Together, these two tidal tails form a rough ring shape. Another fainter tidal tail starts at the apex of the top arc and continues diagonally up and to the left. A smaller galaxy, an almost edge-on spiral, is below and to the left of the central galaxy.
Arp Bot 🤖ArpBot
2025-06-06

Image of Arp 148, also known as Mayall's Object, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Amorphous galaxies - Associated rings. The bottom galaxy likely crashed through the top galaxy, creating a ring and triggering a burst of star formation.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black-and-white image of a pair of galaxies. In the center is a small, wide, bright white vertical line, likely an edge-on galaxy. Above this is a ring galaxy, seen as a blotchy circle. The two galaxies overlap so that the top edge of the edge-on galaxy intersects with the ring galaxy's center. A few white dots, which are stars, fill the black background of space.
Arp Bot 🤖ArpBot
2025-06-06

Image of Arp 282, also known as NGC 169 and NGC 169A, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Double and multiple galaxies - Infall and attraction. NGC 169 (left) and NGC 169A (right) are interacting, creating streams of stars, gas and dust that visibly link the pair of galaxies.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black and white image of a large spiral galaxy is seen in the center of the frame. It's tilted at an angle, so that it's disk appears as an oval rather than a circle. The long axis of the oval is nearly vertical. Dramatic dark dust lanes cross in front of the center of the galaxy. To the right of the spiral is a smaller disk galaxy. It appears to be at almost a right angle to the large spiral. It is overexposed and no details are seen in the center of the galaxy. The two galaxies are connected by a bridge of material. A few white dots, which are stars, are seen on the black background.
Arp Bot 🤖ArpBot
2025-06-05

Image of Arp 15, also known as NGC 7393, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Spiral galaxies - Detached segments. NGC 7393 is a barred spiral galaxy in the constellation Aquarius.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black and white image of a nearly face-on spiral galaxy. Several white dots, which are stars, are seen on the black background.
Arp Bot 🤖ArpBot
2025-06-05

Kitt Peak image of Arp 297, also known as NGC 5755, NGC 5753, NGC 5754 and NGC 5752.

This wide view shows two interacting galaxy pairs. The pairs are actually unrelated and are at different distances.

Credit: KPNO, NOIRLab, NSF, AURA, B. Lofquist, A. Block
Source: noirlab.edu/public/images/noao

Four small galaxies, arranged in two pairs, on a field of stars. The bottom pair of galaxies is a large face-on barred spiral galaxy and a smaller edge-on disk galaxy. The spiral has a bright, pale yellow, circular core that transitions into a diagonal bar structure. Two well-defined spiral arms circle around the core counter-clockwise, beginning at the ends of the bar. To its right is its smaller companion galaxy. It is oval-shaped, running diagonal and with the long axis parallel to the bar of the large spiral. The upper pair is two nearly face-on spiral galaxies. The bottom galaxy of the pair has a blue-white core and bar with two faint spiral arms that make a S-shape. The top galaxy of the pair has a circular yellow core and several spiral arms that wrap around the core.
Arp Bot 🤖ArpBot
2025-06-04

Sloan Digital Sky Survey image of Arp 285, also known as NGC 2854 and NGC 2856.

This pair of galaxies is connected by a bridge of material, indicating a past interaction.

The upper galaxy, NGC 2856, has a clumpy tail extending perpendicular to its disk. It's an example of a “beads on a string” feature, where gravity creates knots of star formation at regular ~3,000 light year intervals.

Credit: SDSS
Source: legacysurvey.org/viewer?ra=141

A somewhat low-res image of a pair of widely-space interacting spiral galaxies. The galaxy in the top left has a bright disk seen at a slight angle so that it appears oval-shaped. Its spiral arms are fainter and hard to see. A thin, blue, clumpy line extends above the galaxy, perpendicular to its disk. The galaxy in the lower right has a strong bar and two spiral arms, forming a distinct S shape. The bar is brighter and yellow-ish. The arms are bluer and dotted with teal star clusters. Faint streams of blue material extend outwards from the ends of the spiral arms. The top stream almost connects with the galaxy in the top left. Several foreground stars are seen as bright points with eight diffraction spikes. The black background of space is dotted with stars and small background galaxies
Arp Bot 🤖ArpBot
2025-06-04

Image of Arp 84, also known as NGC 5394 and NGC 5395, from the Atlas of Peculiar Galaxies by Halton Arp (1966).

In the original catalog, it was in the category: Spiral galaxies - Large, high surface brightness companions. This interacting pair is sometimes called the "Heron Galaxy". The larger spiral, NGC 5395 forms the body of the heron and the smaller, two-armed NGC 5394 forms its neck, head, and beak.

Source: ned.ipac.caltech.edu/level5/Ar

A grainy, black and white image of a pair of interacting spiral galaxies that somewhat resembles a heron. To the upper right is a smaller, distorted spiral, forming the heron's neck, head, and beak. In its center is a bright nucleus surrounded by a ring of stars. Extending from the ring are two large, thin spiral arms, dotted with star clusters, which form an S-shape. The lower arm appears to touch the edge of the disk of its companion galaxy. On the left is a large spiral galaxy, forming the heron's body. It's disk is tilted, so that it appears as a oval rather than a circle. It has a bright center that transitions into spiral arms. The arms are defined by dark brown dust lanes. The area in between is filled with a haze of bright stars. On the black background of space are foreground stars, some with diffraction spikes, and tiny background galaxies. A few white dots, which are stars, are seen on the black background of space.

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