The galaxy M87 threw an entire star cluster towards Earth at more than two million miles per hour.
The star cluster, dubbed HVGC-1, is now on a "fast journey to nowhere," a Harvard-Smithsonian Center for Astrophysics news release reported.
"Astronomers have found runaway stars before, but this is the first time we've found a runaway star cluster," Nelson Caldwell of the Harvard-Smithsonian Center for Astrophysics, said in the news release.
"HVGC" stands for hypervelocity globular cluster, which come from the early universe. They usually contain thousands of stars are a few dozen light-years across.
The Milky Way itself holds 150 globular clusters while the elliptical galaxy M87 holds thousands.
The team noticed the lonely star cluster when studying the space around m87. The researchers sorted targets by color in order to separate stars and galaxies; they used the "Hectospec instrument on the MMT Telescope in Arizona" in order to closely examine the globular clusters.
A computer was used to analyze the data the researchers had gathered, and determine the speed of each cluster. Any "oddity" the computer picked up was examined in person by the researchers. The majority of the targets turned out to be computer glitches, but HVGC-1 caught the team's attention.
"We didn't expect to find anything moving that fast," Jay Strader of Michigan State University, a co-author on the study, said in the news release.
The researchers are unsure how the star cluster was ejected at such a high speed. One suggestion is that M87 could have two supermassive black holes at its center. The star cluster could have gotten too close to the black holes, which would have acted as a "slingshot" and threw the cluster towards the edge of the galaxy at breakneck speed.
Star cluster HVGC-1 is moving so fast that it will most likely escape M87 completely and end up in intergalactic space.
