A stunning new image from the Hubble Space Telescope shows three galaxies headed for a collision and merger. Although galactic collisions are fairly common, this one is rare because each of the trio of galaxies is in the process of giving birth to new stars.
The three galaxiesseen in the constellation Booted, will eventually merge to form a single large galaxy. In the process, the spiral structure the galaxies now display will be obliterated as a result of gravitational interactions between the trio.
The image shows the three galaxies, collectively known as SDSSCGB 10189, close enough to appear to be merging. The shapes of the galaxies are already distorted, and strands of gas and dust can be seen connecting them. The three galaxies emit a lot of light.
As the collision unfolds, an incoherent spiral galaxy to the left sits calmly, almost like a cosmic equivalent of a passerby “rubbing” a more mundane collision taking place on a highway here on our planet.
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Within SDSSCGB 10189, the three major star-forming galaxies are only 50,000 light years apart from each other. While this may seem like a large distance that is not in much danger of collision, in cosmic terms it is actually very close. For example, Andromedathe nearest galaxy to our own The Milky Wayis over 2.5 million light years away sun.
The new The Hubble Space Telescope The image is part of a survey of the origins of the largest and most massive galaxies in the universewhich astronomers call Brightest Cluster Galaxies (BCGs).
BCGs form when a large galaxy swallows smaller galaxies or when gas-rich galaxies like this trio collide and merge. Such cluster galaxies can be used to trace the formation of galactic clusters, which are huge cosmic structures made up of hundreds or even thousands of galaxies. Researchers also hope that BCGs can provide clues about the development of the so-called “cosmic web,” the tangled structure of clumps and filaments of material formed by dark matter which connects individual galaxies in a cluster.
There is still controversy surrounding BCGs and when in the 13.8 billion year history of the universe they formed. Some astronomers believe these massive bright galaxies formed during an early epoch of the universe when it was about 19% of its current age. Others believe BCGs are still forming and evolving today.
The merger of SDSSCGB 10189 may result in the birth of a BCG and thus may finally shed light on the mystery of how and when these massive bright galaxies form.
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