Hypervelocity Stars Are Runaways From Another Galaxy?

According to a new study, the origin of hypervelocity stars may come with a quite unexpected twist. These extremely fast moving cosmic bodies are seemingly runaways that left their galaxy and were later absorbed into our own.

This latest research on such stars was conducted by scientists part of the University of Cambridge in the United Kingdom. They base their research on data gathered by the Sloan Digital Sky Survey. This was taken and introduced in computer simulations.

Based on these, the team determined that hypervelocity stars ‘escaped’ “their original home when the explosion of one star in a binary system caused the other to fly off with such speed that it was able to escape the gravity of the LMC and get absorbed into the Milky Way.”

The high-speed moving objects were believed to have once been part of the Large Magellanic Cloud (LMC). This is a dwarf galaxy that is orbiting the Milky Way.

Hypervelocity Stars, Usually Noticeable in the Northern Hemisphere

Scientists detected about 20 such fast moving cosmic bodies, all of them being massive blue stars. Most of them have been observed in a particular part of the northern hemisphere. Still, scientists believe that others could and would be noticeable only from the southern hemisphere.

Large blue stars have been noted to collapse into either black holes or neutron stars once they run out of fuel.

The new theory put forth by this latest paper is based on binary star systems. This suggests that among the two stars orbiting each other at very high speeds, one of them would most likely explode as a supernova. In turn, the other would leave its system and be a runway.

This term is used for describing a star that escapes its galaxy as it flies off at a speed equal to its orbiting one.

The paper also points out that such a phenomenon could not take place in slow-moving galaxies such as the Milky Way. LMC is the most likely source of hypervelocity stars if this theory proves true. It is the largest and also fastest of the galaxies known to orbit the Milky Way.

Research results will be published in a paper in the journal Monthly Notices of the Royal Astronomical Society. They will also be presented on July 05 as part of the National Astronomy Meeting ongoing in Hull, U.K.

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