Sep 4, 2022 - Science

When galaxies collide

A galaxy with two bright spots near the middle showing black holes with gas and dust swirling around
The galaxy NGC 7727 seen by the Very Large Telescope. Photo courtesy of ESO

About 1 billion years ago, two galaxies merged, creating a new galaxy seen in a photo taken by a telescope in the Southern Hemisphere.

Why it matters: Galaxies can grow and evolve through collisions like this one, giving scientists a glimpse into the diversity of these types of objects out there in the universe.

What they found: The galaxy — called NGC 7727 — began to form when two galaxies danced around one another, disrupting their gas and dust, changing the way they each look about 1 billion years ago.

  • The "tangled trails" in the photo taken by the European Southern Observatory's Very Large Telescope were produced during the merger as stars and dust were stripped from their home galaxies and combined into one, the ESO said.
  • "The core of NGC 7727 still consists of the original two galactic cores, each hosting a supermassive black hole," the ESO said in a statement. "Located about 89 million light-years away from Earth, in the constellation of Aquarius, this is the closest pair of supermassive black holes to us."
  • The two black holes are about 1,600 light-years away from one another and will merge within 250 million years, producing a more massive black hole, the ESO added.

The big picture: The Milky Way is heading toward its own slow-speed cosmic collision with the Andromeda Galaxy billions of years from now, so learning more about these kinds of crashes could help scientists understand more about our own galaxy's future.

Editor's note: This piece was first published in the Axios Science newsletter on Aug. 25.

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