A new image from the NASA/ESA Hubble Space Telescope captures an ongoing head-on collision between the star-forming spiral galaxy NGC 2445 an the less flashy spiral galaxy NGC 2444.
Collectively called Arp 143, the NGC 2445-NGC 2444 system is located some 181 million light-years away in the constellation of Lynx.
The galaxies collided head-on, igniting the uniquely shaped star-formation firestorm in NGC 2445, where thousands of stars are bursting to life on the right-hand side of the image.
NGC 2445 is awash in starbirth because it is rich in gas, the fuel that makes stars. However, it hasn’t yet escaped the gravitational clutches of its partner, NGC 2444.
The galaxy duo is waging a cosmic tug-of-war, which NGC 2444 appears to be winning.
NGC 2444 has pulled gas from NGC 2445, forming the oddball triangle of newborn stars.
“Simulations show that head-on collisions between two galaxies is one way of making rings of new stars,” said Dr. Julianne Dalcanton, an astronomer with the Center for Computational Astrophysics at the Flatiron Institute and the University of Washington.
“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 responsible for yanking strands of gas from its partner, stoking 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 started on NGC 2445’s outskirts and continued inward.
Researchers estimate the streamer stars were born between about 50 million and 100 million years ago.
But these infant stars are being left behind as NGC 2445 continues to pull slowly away from NGC 2444.
Stars no older than 1 million to 2 million years are forming closer to the center of NGC 2445.
“This is a nearby example of the kinds of interactions that happened long ago,” said Dr. Elena Sabbi, an astronomer at the Space Telescope Science Institute.
“It’s a fantastic sandbox to understand star formation and interacting galaxies.”
Source link: https://www.sci.news/astronomy/hubble-arp-143-10579.html