Hubble captures a ‘space triangle’ created by a galactic collision

The Hubble telescope detected the collision of two galaxies and the blossoming of a large number of new stars.


A spectacular head-on collision between two galaxies  fueled an unusual frenzy of triangular-shaped star birth, as captured in a new Hubble Space Telescope image .

The duo of interacting galaxies is collectively called Arp 143 . The pair contains the bright, distorted, star -forming spiral galaxy NGC 2445 on the right, along with its less conspicuous companion, NGC 2444 on the left.

Astronomers suggest that galaxies crossed paths with each other, igniting the unique star-forming firestorm in NGC 2445, where thousands of stars come to life on the right side of the image. This galaxy is awash in star birth because it is rich in gas, the forming fuel. However, it has not yet escaped the gravitational clutches of its companion NGC 2444, shown on the left side of the image. The pair are waging a cosmic tug-of-war, which NGC 2444 appears to be winning. The galaxy has extracted gas from NGC 2445,forming the strange triangle of newly minted stars .

“Simulations show that head-on collisions between two galaxies are a way of forming rings of new stars, ” astronomer Julianne Dalcanton of the Center for Computational Astrophysics at the Flatiron Institute in New York and the University of Washington in Seattle said in a statement.

“So star-forming rings are not uncommon. What’s strange about this system, though, is that it’s a star-forming triangle. Part of the reason for that shape is that these galaxies are still very close to each other and NGC 2444 is still clinging to the other galaxy gravitationally. NGC 2444 may also have an invisible halo of hot gas that could help push NGC 2445 ‘s gas away from its core. Therefore, they are not yet completely free from each other, and their unusual interaction is distorting the ring into this triangle.”

serpentine stars

NGC 2444 is also responsible for ripping candy-like strands of gas from its companion, fanning the streamers of young blue stars that appear to form a bridge between the two galaxies.

These streamers are among the first in what appears to be a wave of star formation that began on the outskirts of NGC 2445 and continued inward. The researchers estimate that the serpentine stars were born between 50 and 100 million years ago. But these infant stars are being left behind as NGC 2445 continues to slowly move away from NGC 2444 .

Stars that are no more than 1 million to 2 million years old are forming closer to the center of NGC 2445 . Hubble ‘s sharp sharpness reveals a few individual stars. They are the brightest and most massive in the galaxy. Most of the bright blue groups are star clusters. The pink spots are clusters of young, giant stars that are still shrouded in dust and gas.

Although most of the action occurs in NGC 2445 , it doesn’t mean that the other half of the interacting pair escaped unscathed. The gravitational struggle has stretched NGC 2444 into a strange shape. The galaxy contains old stars and no new star birth because it lost its gas a long time ago, long before this galactic encounter.

“This is a close example of the kinds of interactions that happened a long time ago. It’s a fantastic sandbox for understanding star formation and interacting galaxies,” said Elena Sabbi of the Space Telescope Science Institute in Baltimore, Maryland. (EuropePress)