The Sun, its next-door neighbor Proxima Centauri, as well as most of the stars scientists have observed throughout history orbit the center of the Milky Way galaxy in a calm, predictable manner. However, there are some stars in our galaxy that have baffled astronomers ever since they were first detected. These unorthodox, “troublemaker” stars move at very fast speeds and are referred to as hypervelocity stars. How and why they developed such unorthodox orbits so far remained a matter of speculation in the scientific community worldwide.
However, that’s about to change now.
A group of researchers from the University of Cambridge claims to have cracked the mystery of these hypervelocity stars. The researchers made use of data from the Sloan Digital Sky Survey and computer simulations to demonstrate that these runaway stars probably originated in the Large Magellanic Cloud (LMC), a dwarf galaxy orbiting the Milky Way.
The simulations show that these fast-moving stars were able to escape their home galaxy when the violent explosion of one star in their binary systems caused the others to fly off at such a speed that the cumulative gravity of the dwarf galaxy was unable to prevent their escape. Eventually, they were captured by the Milky Way.
“Earlier explanations for the origin of hypervelocity stars did not satisfy me,” said Douglas Boubert, a PhD student at Cambridge’s Institute of Astronomy and the paper’s lead author. “The hypervelocity stars are mostly found in the Leo and Sextans constellations – we wondered why that is the case.”
The larger consensus prior to this new study was that the hypervelocity stars, which are mostly large blue stars, may have been pushed away from the center of the Milky Way by the supermassive black hole therein. As of today, astronomers have observed roughly 20 hypervelocity stars in the northern hemisphere, although they think there are many more in the southern hemisphere too.
The findings of the study have been published in the Monthly Notices of the Royal Astronomical Society and was presented yesterday at the national Astronomy Meeting in Hull.