6 beautiful galaxy collisions seen by the Hubble Space Telescope

The study of galaxy collisions using the Hubble Space Telescope is revealing the secrets of star formation and galactic evolution.

Astronomers have released 6 incredible images of colliding galaxies, illustrating some of the violent, energetic yet beautiful processes that occur throughout the cosmos.

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We’ve come a long way since astronomy’s Great Debate of 1920, when astronomers debated the scale of the Universe and whether distant galaxies did indeed exist. Today’s astronomers benefit from space telescopes like the Hubble Space Telescope, orbiting Earth and giving us incredible views of galactic formation and collisions.

Galaxy NGC 3256, about 100 million lightyears away, formed as a result of a merger of two galaxies. Credit: ESA/Hubble, NASA
Galaxy NGC 3256, about 100 million lightyears away, formed as a result of a merger of two galaxies. Credit: ESA/Hubble, NASA

Galaxy mergers or collisions are of great interest to astronomers and astrophysicists because they can reveal much about the processes of star formation in the Universe.

Galaxy system NGC 1614, Note the bright centre and two spiral arms. The asymmetrical structure of the galaxy is probably a result of tidal interactions between two galaxies that merged to produce the object seen here. Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)
Galaxy system NGC 1614, Note the bright centre and two spiral arms. The asymmetrical structure of the galaxy is probably a result of tidal interactions between two galaxies that merged to produce the object seen here. Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

During galactic mergers, the distances between individual stars are so vast that it is unlikely that any would directly collide, but the gravitation forces at work cause dust and gas to be churned up, dramatically increasing the rate at which new stars begin to be born.

This galactic merger is known as the Medusa merger, as it supposedly looks like the writhing snakes that form the Greek Gorgon’s hair. Astronomers think that in the case of NGC 4194, to give it its formal name, an early galaxy consumed a smaller gas-rich system, ejecting streams of stars and cosmic dust into space. Credit: ESA/Hubble & NASA, A. Adamo
This galactic merger is known as the Medusa merger, as it supposedly looks like the writhing snakes that form the Greek Gorgon’s hair. Astronomers think that in the case of NGC 4194, to give it its formal name, an early galaxy consumed a smaller gas-rich system, ejecting streams of stars and cosmic dust into space.
Credit: ESA/Hubble & NASA, A. Adamo

In our own galaxy the Milky Way, typically star clusters are formed with masses about 10 thousand times that of the Sun. In colliding galaxies, star clusters can form that reach millions of times the mass of our Sun.

Each of the 6 mergers seen here was studied during the HiPEEC survey, which is investigating the rate of new star formation within galaxy collisions.

NGC 6052 is a pair of colliding galaxies in the constellation of Hercules about 230 million light-years away. It was discovered by William Herschel in 1784 and originally thought to be a single irregular galaxy. Credit: ESA/Hubble & NASA, A. Adamo et al.
NGC 6052 is a pair of colliding galaxies in the constellation of Hercules about 230 million light-years away. It was discovered by William Herschel in 1784 and originally thought to be a single irregular galaxy. Credit: ESA/Hubble & NASA, A. Adamo et al.

The data collected can also tell astronomers a lot about how galaxies evolve over time, and what role collisions play in the changes that occur throughout the lifetime of a galaxy.

Hubble’s ultraviolet and near-infrared observations can be used to calculate the ages and masses of star clusters within the collisions, as well as the rate of new star formation.

Two beautiful spiral galaxies merged millions of years ago to produce this strange-looking galactic object. The bright centre is a result of new bursts of star formation generated by the churning of cosmic gas and dust within the galaxies. Credit: ESA/Hubble & NASA, A. Adamo et al.
Two beautiful spiral galaxies merged millions of years ago to produce this strange-looking galactic object. The bright centre is a result of new bursts of star formation generated by the churning of cosmic gas and dust within the galaxies. Credit: ESA/Hubble & NASA, A. Adamo et al.
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These star clusters will shine brightly long after the most dramatic stages of the collision have faded away, acting as cosmic mementos of the dramatic processes that changed the fate of each galaxy forever.

Two beautiful spiral galaxies merged millions of years ago to produce this strange-looking galactic object. The bright centre is a result of new bursts of star formation generated by the churning of cosmic gas and dust within the galaxies. Credit: ESA/Hubble & NASA, A. Adamo et al.
Two beautiful spiral galaxies merged millions of years ago to produce this strange-looking galactic object. The bright centre is a result of new bursts of star formation generated by the churning of cosmic gas and dust within the galaxies. Credit: ESA/Hubble & NASA, A. Adamo et al.