Hubble captured this stunning image of two galaxies interconnected. They likely passed through each other, which led to them to explode in a “frenzy for starbirth.”
Collectively Called Arp
The unusual star-birthing frenzy of Arp 143 has resulted from the head-on collision between galaxies. This pair includes NGC 2445, a very bright spiral galaxy that NASA calls “glittery”, and NGC 2444, a much less flashy companion.
NASA astronomers believe that the two galaxies crossed each other, which caused a beautiful traingle-shaped firestorm in NGC2445. This firestorm has seen thousands of stars bursting to life due to the abundance of gas created by the collision of the galaxies. It has yet to escape the gravity of NGC2444 despite its spectacular, stunning eruption of star formation. NASA claims that the two are engaged in a cosmic tug-of war. NGC2444 seems to be winning, as it has pulled gas form NGC2445, the source of the unusual star formation’s triangle shape.
“Simulations have shown that head-on collisions of two galaxies are one way of making rings of stars,” Julianne Dalcanton, an astronomer at the Flatiron Institute’s Center for Computational Astrophysics (New York) and the University of Washington (Seattle), says.
“Rings of star formation are therefore not unusual. What’s strange about this system is the fact that it’s a triangular star formation. These galaxies are so close together that NGC 2444 still holds onto the other galaxy. NGC 2444 could also be covered by an invisible hot gas halo that may help pull NGC 2445 gas from its nucleus. They are not yet completely independent of one another, and their unusual interaction is distorting this triangle.
NGC 2444 is seen pulling gas from NGC 2445 at the center of the photo, which creates a bridge between two galaxies. NASA describes the gas’ appearance as “taffy-like”.
These streams, which are colored blue in this photo, seem to be a wave in star formation that began at NGC 2445’s outer edges and continues inward. NASA says that these stars were formed between 50 million to 100 million years ago. These stars are being lost as NGC2445 slowly pulls away from NGC2444.
Hubble allows us to see stars that are younger than NGC 2445, which is about one to two million years. These stars are the brightest and largest in the galaxy. The stars that appear blue are groups of stars, while the pink stars are large, young star clusters.
NGC 2444 will not be able to escape this arrangement unharmed. NGC 2444 has been stretched out by gravity. NASA claims that the galaxy has lost its gas well before this galactic encounter.
“This is an example of the types of interactions that occurred long ago. It’s a wonderful sandbox for understanding star formation and inter-galaxies,” Elena Sabbi, of Baltimore’s Space Telescope Science Institute, Maryland says.
Collision can also cause star formation
Arp 143 is not the first example of star formation caused by collisions of galaxies. NASA published in 2018 a photo called “Hubble’s Cartwheel”, which shows a galaxy with a cartwheel-shaped shape that was created by a violent galactic collision.