The compact star US 708 did not have an easy life. With a more powerful stellar partner, 708 lost its mass until it became a compact orb filled with helium.
But 708 is not just finished in the void. Scientists believe that instead, it exploded a supernova, discarding the ruined remnants with such force that they leave the galaxy.
A new study shows that the star, classified as a hot subdwarf, created a blast wave that is 750 kilometers per second faster than any other star in the galaxy.
The study shows that this is one of 20 such supernova explosions that have occurred with such monstrous power. Other stars who travel fast enough to overcome the Milky Way's gravitational field were blocked by a black hole hiding in the center of the galaxy.
US 708 will leave the Milky Way in 25 million years, cooling over time and turning into a white dwarf. Astronomers first discovered the star in 2005, but at that time it was only possible to determine the speed, but not its fast rotation, which later proved its past.
In 2009, theorists developed computer models showing that stars can reach speeds, allowing them to escape from galaxies, thanks to supernova explosions.
"It made us study US 708 more closely," said astronomer Stefan Geyer, from the European Southern Observatory.
The US 708 star has always been unusual, since all other famous stars moving at hypersonic speeds are the main sequence stars. In contrast, US 708 is a compact, helium-filled star that formed near a more massive star, pumping almost all of its hydrogen.
