Astronomers have recently observed galaxy collisions but they were surprised to see that the tumultuous process resulted in the formation of a strange eye-shaped feature. The eye was formed thanks to a high density of stars and gas that keep crashing in the middle of a disk from a spiral galaxy known as IC 2163. The massive wave of matter was triggered when the galaxy collided with the side of another galaxy known as NGC 2207.
Scientists used the Atacama Large Millimeter/submillimeter Array (ALMA) to discover the arcs in the spiral galaxy that quite resemble a pair of eyelids. According to Michele Kaufman, the lead author of the paper recently published in the Astrophysical Journal, although these types of galaxy collisions are not uncommon, only a few featuring similar ocular structures have been discovered as of yet.
The researchers have noted that the rarity of this phenomenon is only due to the fact that it only lasts a few millions of years. This amount of time is insignificant compared to the lifespan of a galaxy. As such, the discovery of new galactic eyelids provides researchers with an excellent opportunity to learn about the implications of partial galaxy collisions.
The collision that formed the eyelids is only the first one in a series that will eventually end with the merger of the galaxies. They are located in Canis Major constellation, which is 114 million light-years away from Earth.
Astronomers have come to believe that similar phenomenon were more prevalent in the early years of the universe when collisions between galaxies were quite common because of their proximity to each other. However, the resulting eyelids wouldn’t resemble the recently discovered ones because the galactic disks were more clumpy and irregular back then.
During their study, the scientist also used computer models to predict in what ways could these eyelids evolve depending on the various ways the galaxies interact with each other. However, real observational evidence will provide a great boost to their research. They are continuing to study galaxy collisions and comparing the various properties of star clusters observed by Hubble with the those of the molecular clouds detected by ALMA.
The purpose of the research is to help understand how different the clouds and stars inside the eyelids are when compared to standard cosmic objects in the others part of the two galaxies.
Image credit: M. Kaufman; B. Saxton (NRAO/AUI/NSF