Skip to main content

Hubble captures a pair of galaxies merging into an unusual ring shape

This week’s image from the Hubble Space Telescope shows a collection of galaxies, with an unusual merging pair as the star of the show. The merging galaxy pair Arp-Madore 417-391 is located 670 million light-years from Earth in the constellation of Eridanus, which is in the southern celestial hemisphere.

The pair are classified as a “peculiar galaxy” because of the way their shapes have been distorted by their interaction. “The Arp-Madore catalog is a collection of particularly peculiar galaxies spread throughout the southern sky, and includes a collection of subtly interacting galaxie,s as well as more spectacular colliding galaxies,” Hubble scientists write.

The galaxy merger Arp-Madore 417-391 steals the spotlight in this image from the NASA/ESA Hubble Space Telescope. The Arp-Madore catalog is a collection of particularly peculiar galaxies spread throughout the southern sky, and includes a collection of subtly interacting galaxies as well as more spectacular colliding galaxies. Arp-Madore 417-391, which lies around 670 million light-years away in the constellation Eridanus in the southern celestial hemisphere, is one such galactic collision. The two galaxies were distorted by gravity and twisted into a colossal ring, leaving their cores nestled side by side.
The galaxy merger Arp-Madore 417-391 steals the spotlight in this image from the NASA/ESA Hubble Space Telescope. ESA/Hubble & NASA, Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA, J. Dalcanton

Galaxy mergers happen when two or more galaxies get close enough together that their gravity begins to affect one another. When galaxies collide, one of them can be annihilated, or the two can merge to form one larger galaxy. Which outcome occurs is thought to be to do with the supermassive black holes that lie at the heart of almost every galaxy.

As galaxies get closer together, the tremendous gravitational forces involved can pull them out of their normal shapes. Galactic arms can be pulled into a new direction or, as in this case, even more dramatic distortions can occur. The two galaxies involved in this merger have formed a ring shape, with the two brightly glowing cores around their supermassive black holes sitting close together.

The image was captured with Hubble’s Advanced Camera for Surveys (ACS) instrument, which operates in the visible light and ultraviolet wavelengths, and which took some of Hubble’s most famous images such as its Ultra Deep Field image. This image was taken as part of a program to identify interesting objects that could be further studied in greater depth with tools like the James Webb Space Telescope.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Hubble image shows a lonely star glowing over an irregular background galaxy
The bright star BD+17 2217. Arp 263 – also known as NGC 3239 in the foreground and irregular galaxy Arp 263 in the background.

This week's image from the Hubble Space Telescope is notable for the way it was composed as much as for the object it shows. Composed of two different exposures which have been merged, it shows the star BD+17 2217 shining over the background irregular galaxy Arp 263.

Irregular galaxies are those with irregular structures, unlike elliptical galaxies or spiral galaxies such as our Milky Way. Arp 263 is patchy and cloudy, with some areas glowing brightly due to star formation while other areas appear practically bare. Such galaxies are typically formed due to interactions with other galaxies, which can occur when a massive galaxy passes by and pulls the original galaxy out of shape. In the case of Arp 263, it is thought that it developed its irregular shape when two galaxies merged.

Read more
Hubble observes a cluster of boulders around impacted asteroid Dimorphos
A NASA/ESA Hubble Space Telescope image of the asteroid Dimorphos taken on 19 December 2022.

Last year, NASA deliberately crashed a spacecraft into an asteroid, in a first-of-its-kind test of planetary defense. At the time, telescopes around the world including the Hubble Space Telescope observed the impact between the DART spacecraft and the Dimorphos asteroid, capturing footage of the plumes of dust thrown up. Now, Hubble has observed Dimorphos once again and seen that a number of boulders have been ejected from the asteroid.

The Hubble image shown below was taken on 19 December 2022, around four months after the impact, and shows the bright streak of the asteroid across the sky, surrounded by small boulders which were knocked loose during the impact. This view was only possible after several months as the impact initially sent up large amounts of dust which made it difficult to see the asteroid in detail.

Read more
One galaxy, two views: see a comparison of images from Hubble and Webb
The peculiar galaxy NGC 3256 takes centre stage in this image from the NASA/ESA Hubble Space Telescope. This distorted galaxy is the wreckage of a head-on collision between two spiral galaxies which likely occurred 500 million years ago, and it is studded with clumps of young stars which were formed as gas and dust from the two galaxies collided.

It might not seem obvious why astronomers need multiple different powerful space telescopes. Surely a more powerful telescope is better than a less powerful one? So why are there multiple different telescopes in orbit, either around Earth or around the sun?

The answer is to do with two main factors. One is the telescope's field of view, meaning how much of the sky it looks at. Some telescopes are useful for looking at large areas of the sky in less detail, working as survey telescopes to identify objects for further research or to look at the universe on a large scale -- like the recently launched Euclid mission. While others, like the Hubble Space Telescope, look at small areas of the sky in great detail, which is useful for studying particular objects.

Read more