NASA's Hubble Telescope captures unusual 'Space Triangle': Here's what you need to know

Two galaxies colliding: A head-on collision between the two galaxies created an unusual 'Space Traingle'. The spectacular star-birthing frenzy was captured by NASA’s Hubble Space Telescope.

Just passing through…

The two interacting galaxies that make up Arp 143 likely passed through one another, igniting a frenzy of starbirth in the glittering galaxy on the right.

This galaxy is rich in gas, the fuel that makes stars: https://t.co/kulVN1Z6oB pic.twitter.com/sqZ0Cw8B0g

— Hubble (@NASAHubble) February 22, 2022

The colliding galaxies are collectively called Arp 143. At the right side of the image, there is a glittery, distorted, star-forming spiral galaxy NGC 2445, while at the left is a less flashy galaxy NGC 2444. 

According to the astronomers, the collision of the galaxies created a unique triangular shape where thousands of stars are birthing to life. The galaxy at the right-hand side of the image is birthing stars as it is super rich in gas that creates stars. However, it hasn't escaped the gravitational clutches of its partner NGC 2444. The ongoing cosmic tug-of-war between the two galaxies resulted in the unusual shape and NGC 2444 appears to be winning.

Galaxy collisions are the ultimate in slow-motion stunts. ⏱️
When a pair of galaxies encounters each other, it takes 1-2 billion years for them to merge and settle down. The stars already in the galaxies don’t change much, but the collision can spark lots of new stars to form! ✨ pic.twitter.com/JdxnVqj6T9

— NASA Universe (@NASAUniverse) April 9, 2020

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"Simulations show that head-on collisions between two galaxies are one way of making rings of new stars," said astronomer Julianne Dalcanton of the Flatiron Institute’s Center for Computational Astrophysics in New York and the University of Washington in Seattle.

The astronomer added, "Therefore, rings of star formation are not uncommon. However, what’s weird about this system is that it’s a triangle of star formation. Part of the reason for that shape is that these galaxies are still so close to each other and NGC 2444 is still holding on to the other galaxy gravitationally. NGC 2444 may also have an invisible hot halo of gas that could help to pull NGC 2445’s gas away from its nucleus. So they’re not completely free of each other yet, and their unusual interaction is distorting the ring into this triangle."

NGC 2444 is also pulling strands of gas from its partner galaxy, thereby stoking the streamers of young, blue stars that appear to form a bridge between the two. 

The formation of streamers first started on the outskirts of NGC 2445 and then continued inwards. However, these were left behind as  NGC 2445 continues to pull away from NGC 2444. According to the estimates by the researchers, the streamers were born around 50 to 100 million years ago. The stars forming closer to the centre of NGC 2445 are around 1 to 2 million years old. 

NASA's Hubble telescope reveals individual stars which are the brightest and massive in the galaxy, along with pink blobs that are giant young star clusters that are enshrouded in dust and gas. 

While much of the activity is happening in NGC 2445, the other half is not left unscathed. The gravitational tussle between the two galaxies has stretched NGC 2444 into an odd shape. This galaxy has old stars and there is no new star birth due to the loss of gas. 

“This is a nearby example of the kinds of interactions that happened long ago. It’s a fantastic sandbox to understand star formation and interacting galaxies,” said Elena Sabbi of the Space Telescope Science Institute in Baltimore, Maryland.

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