Astronomers have found a runaway globular cluster headed right for the Milky Way. The hypervelocity is hurtling straight towards the galaxy at a blistering speed of two million MPH.
Astronomers have been observing globular clusters for hundreds of years. However, the recently discovered HVGC-1 hypervelocity star cluster is an oddball, a very fast and very large oddball. Most globular clusters can be found orbiting the central areas of galaxies such as the Milky Way and the M87 galaxy. These clusters contain around 100,000 stars grouped together into large spherical celestial bodies. Moreover, globular clusters often travel around their home galaxies at relatively slow speeds. In the case of the HVGC-1 however, the M87 galaxy may have chosen to fire the cluster as a bullet speeding towards the Milky Way.
"Astronomers have found runaway stars before, but this is the first time we've found a runaway star cluster," said Harvard-Smithsonian Center for Astrophysics astronomer Nelson Caldwell.
Compared to the Milky Way, the M87 galaxy is on a totally different scale in terms of size and mass. The massive blob-shaped galaxy is around 53 million light years away. It is also 10 times more massive than the Milky Way. Astronomers believe that the HVGC-1 may have strayed too close to the supermassive black holes found in the center of the M87 galaxy. Close contact with the galactic core may have resulted in a gravitational reaction that could have caused the cluster to be ejected out of the M87 galaxy at speeds never before seen in a globular cluster. The astronomers that found the cluster published their findings in The Astrophysical Journal Letters.
"We didn't expect to find anything moving that fast," said Michigan State University astronomer Jay Strader. Strader is one of the co-authors of the study.
Globular clusters are said to be formed by left over materials from the formation of the universe. These highly compact groupings of stars are actually quite common. The Milky Way alone contains around 150 clusters. Unlike the Milky Way however, the M87 galaxy is said to contain thousands of these clusters. Using an instrument found in the MMT Telescope located in Arizona, the researchers were able to observe the clusters in the M87 galaxy. The instrument is known as the Hectospec, a multi-object spectrograph that can be used to observe numerous celestial objects at moderate resolutions.
The scientists then used a computer to analyze the data they gathered from the clusters contained with the M87 galaxy. During the analysis, a number of anomalies were found. However, many of the anomalies turned out to be glitches in the computer analysis. Upon closer inspection, the team found HVGC-1. The analysis also confirmed both the speed and the trajectory of the runaway globular cluster. HVGC is an acronym for Hypervelocity Globular Cluster.