NASA / ESA’s Hubble Space Telescope celebrates its 32nd birthday with a stunning view of an unusual cohesive collection of five galaxies called the Hickson Compact Group 40. This snapshot captures a special moment in their lives as they fall together before merging. Credit: NASA, ESA and STScI
NASA / ESA’s Hubble Space Telescope celebrates its 32nd birthday with magnificent views of the Hickson Compact Group 40, an unusually narrow group of five galaxies. This photo captures a special moment in their lives as they fall together before merging.
This menagerie includes three spiral galaxies, an elliptical galaxy and a lenticular (lens-like) galaxy. Somehow, these different galaxies intersected to create an unusually overcrowded and diverse sampler of galaxies.
NASA / ESA’s Hubble Space Telescope celebrates its 32nd birthday with a stunning view of an unusual cohesive collection of five galaxies.
Caught in a calm gravitational dance, the whole group is so densely packed that it can fit into a space that is less than twice the diameter of the star disk of our Milky Way.
Although such galactic groups can be found in the center of massive galaxy clusters, these galaxies are remarkable in that they are isolated in their own small area of the universe, in the direction of the constellation Hydra.
This image shows a wide field view centered on the Hickson Compact Group 40. Credit: ESA / Hubble, Digitized Sky Survey 2, Acknowledgment: D. De Martin
One possibility is that there is very dark matter (misunderstood and invisible form of matter) associated with these galaxies. If they get close to each other, dark matter can form a large cloud in which galaxies orbit. As galaxies pass through dark matter, they feel the force of friction that results from its gravitational effects. This slows their movement and causes galaxies to lose energy, so they fall together. As a result, this image captures galaxies at a particularly special time in their lives. Eventually, they will collide and combine to form a giant elliptical galaxy in about 1 billion years.
NASA / ESA’s Hubble Space Telescope celebrates its 32nd birthday with a stunning view of an unusual cohesive collection of five galaxies called the Hickson Compact Group 40. This snapshot captures a special moment in their lives as they fall together before merging. Credit: NASA, ESA and STScI
This compact galactic group has been studied not only in visible light, but also in radio, infrared and X-ray wavelengths. Almost all galaxies have a compact source of radio emission in their nucleus, which may indicate the presence of a supermassive black hole. X-ray observations reveal that galaxies interacted by gravity, as evidenced by the presence of large amounts of hot gas among them. Infrared observations reveal clues to the speed at which new stars are evolving.
Although more than 100 such compact galaxy clusters have been cataloged in sky research decades ago, the Hickson Compact Group 40 is one of the most densely packed. Observations suggest that such narrow clusters may have been more abundant in the early universe and provided fuel to power black holes known as quasars, whose light from overheated inflatable material blazed into space. Studying the details of galaxies in close groups like this helps astronomers understand when and where galaxies are assembled and what they are made of.
For more information, see Hubble’s 32nd Birthday Celebration: A Stunning Look at an Unusual Collection of Five Galaxies.
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The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
As Hubble celebrates its 32nd anniversary, here are some compelling facts about the famous observatory’s achievements and impact:
- Launched on April 24, 1990, NASA / ESA’s Hubble Space Telescope made more than 1.5 million observations of about 50,000 celestial objects.
- Astronomers using Hubble data have published more than 19,000 scientific papers, more than 1,000 of which were published in 2021.
- Approximately 100,000 citations attributed to Hubble accumulate every three years. On average, each article based on Hubble data has approximately 54 citations.
The observations were made as part of the Hubble Observatory Program 16848 (PI: C. Britt).
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