NASA’s iconic Hubble Space Telescope has captured a spectacular image of an ongoing merger between two galaxies located over 100 million light years from Earth. The dramatic cosmic collision provides astronomers a glimpse into what may be the future fate of our own Milky Way galaxy as it heads towards a collision course with the neighboring Andromeda galaxy in about 4 billion years.
Fate of the Milky Way Seen in Cosmic Crash
The latest Hubble image shows two spiral galaxies, collectively known as Arp 122, that are combining to create a new mega-galaxy. The dramatic encounter has distorted the galaxies’ typical pinwheel shapes as their stars and dust remix in a gravitational battle royal.
As described by astronomers in a report from Fox News, the merging galaxies appear “caught in a maelstrom of star formation, with bright clusters of young stars and star-forming regions being born as the two galaxies engage in their slow-motion collision.” The chaotic scene offers a potential glimpse into how our own Milky Way and the Andromeda galaxies may appear as they collide to form a giant elliptical galaxy in the distant future.
|Galaxy 1 Name
|Arp 122 North
|Galaxy 2 Name
|Arp 122 South
|Distance from Earth
|Over 100 million light years
|Shape Before Collision
|Shape After Collision
As described in WIONews, “The final product of such mergers is a completely new galaxy that no longer resembles its progenitors. In 4 billion years our Milky Way itself will experience a similar fate when it gravitationally merges with our nearest big neighbour, the Andromeda galaxy.”
While galaxy mergers often result in bright bursts of new star formation, they can also feed the birth and rapid growth of humongous black holes that emit intense radiation as surrounding stars and gas spiral into them.
A Cosmic Light Show
The Hubble image captures in vivid detail large clumps of new stars forming at a frenzied pace. As described by Digital Trends, this stellar baby boom is triggering “a cosmic fireworks show as the intense radiation from these young, massive stars heats up and churns surrounding hydrogen gas clouds in the galaxies.”
The most concentrated region of new stars seen in the image is located along the northern edge of the southern Arp 122 galaxy, where an immense amount of hydrogen gas was triggered into collapse to form new stars, likely by pressure from supernova shockwaves and stellar winds. These stellar nurseries are manufacturing young, hot stars 10 to 20 times more massive than our sun.
The Making of a New Mega-Galaxy
The Arp 122 system contains more than 100 million stars, clouds of dust and gas, and an untold number of planets. Astronomers using Hubble and other telescopes will continue tracking this mega-merger over millions of years. The violent collision, which began roughly 750 million years ago, will take eons to complete.
Over time the two galaxies will coalesce into a single, more spherical shaped galaxy about the mass of the Milky Way. This future galaxy is expected to experience its own ongoing mergers with other galaxies it encounters during its lifetime.
What’s Next for the Milky Way and Andromeda?
While the Arp 122 merger gives astronomers a preview into the likely future collision between our Milky Way galaxy and the neighboring Andromeda galaxy (M31), the two situations have some notable differences. For one, the Milky Way and Andromeda are both much larger spiral galaxies compared to the pair of smaller galaxies seen in the Arp 122 image.
In their report on the Hubble discovery, astronomers outline the anticipated timeline and outcome of the coming cosmic crash closer to home:
In about 4 billion years, the Milky Way and Andromeda will make their first close pass toward each other as gravity draws the two giants together. Their outer halo stars will intermingle.
In about 5 billion years, the two galaxies will collide head-on and merge together, their stars intermixing. This violent joining will kick up rampant star formation.
In about 6 billion years, the newly fused galaxy will settle down into an enormous elliptical galaxy. Dark matter and globular clusters will dominate its exterior, surrounding a bright core populated with stars from its two progenitor galaxies.
While this future galactic collision will completely reshape our stellar neighborhood and night sky vista, astronomers reassure there is no need to worry. Since stars and planets in merging galaxy pairs are separated by many light years of empty space, our solar system will peacefully coast along orbiting the new combined galactic center.
So while Arp 122 offers a nearby glimpse of our own distant cosmic destiny, astronomers emphasize these galaxy mergers are relatively common events at the scale of the universe. Hubble and other telescopes will continue to provide ring-side seats to the endless choreography of galaxy formation occurring across the heavens.
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