A new Hubble image shows the peculiar galaxy NGC 1614, located 200 million light-years away in the constellation of Eridanus (The River). Its unusual shape is the result of two galaxies merging long ago in the distant past.
“Owing to its turbulent past and its current appearance, astronomers classify NGC 1614 as a peculiar galaxy, a starburst galaxy, and a luminous infrared galaxy,” Hubble scientists said in a statement. “Luminous infrared galaxies are among the most luminous objects in the local Universe — and NGC 1614 is, in fact, the second most luminous galaxy within 250 million light-years.”
This particular galaxy was shaped by dramatic forces, as the Hubble scientists explain: “NGC 1614 is the result of a past galactic merger which created its peculiar appearance,” they said. “The cosmic collision also drove a turbulent flow of interstellar gas from the smaller of the two galaxies involved into the nucleus of the larger one, resulting in a burst of star formation which started in the core and slowly spread outwards through the galaxy.”
A galactic merger happens when two or more galaxies collide in an often violent interaction. The collision is affected by gravitational forces both within the galaxy, holding the dust and the gas of it together and pulling it toward the galactic center, and between the galaxies, pulling the two objects closer to each other.
Scientists are still puzzling over why these collisions sometimes lead to one of the galaxies being violently destroyed, and other times lead to the two galaxies merging into one new galaxy, as was the case with NCG 1614.
Information from NASA’s Spitzer Space Telescope suggests that the difference between these two outcomes is related to the stability of the supermassive black hole at the heart of each galaxy. Stable supermassive black holes allow the galaxy to continue producing new stars and facilitate merging, while unstable supermassive black holes send out shockwaves that halt star formation and lead to the death of the galaxy.