Newly Discovered 'Hypervelocity Star' May Unlock Secrets of the Galaxy
The newly discovered "hypervelocity star" may provide clues about the supermassive black hole at the center of our Milky Way and the halo of mysterious dark matter surrounding the galaxy, astronomers report.
"The hypervelocity star tells us a lot about our galaxy -- especially its center and the dark matter halo," Zheng Zheng, an assistant professor of physics and astronomy and the study's lead author, said in a statement from the University of Utah.
"We can't see the dark matter halo, but its gravity acts on the star," Zheng added. "We gain insight from the star's trajectory and velocity, which are affected by gravity from different parts of our galaxy."
Traveling at speeds of more than 1 million mph, it is the closest, second brightest and among the largest of 20 such odd stars found in the last decade.
Hypervelocity stars appear to be remaining pairs of binary stars that once orbited each other and got too close to the supermassive black hole at the galaxy's center. Intense gravity from the black hole - which has the mass of 4 million stars like our Sun - captures one star so it orbits the hole closely, and slingshots the other on a trajectory headed beyond the galaxy.
Zheng and his colleagues discovered the new hypervelocity star, named LAMOST-HVS1, while studying other stars in the Milky Way. It's unique for its speed: almost three times the usual star's 500,000-mph pace through space. And despite being the closest hypervelocity star, it is still 249 quadrillion miles (or 42,400 light years) from Earth.
Researchers say only about 5 percent of the universe is made of visible matter, 27 percent is invisible and yet-unidentified dark matter and 68 percent is even more mysterious dark energy. By traveling through the dark matter halo, the new hypervelocity star's speed and trajectory can reveal something about the mysterious halo.
The study, published in Astrophysical Journal Letters, assures us that though LAMOST-HVS1 outshines our Sun by 400 times and burns even hotter, it and other hypervelocity stars pose no danger to Earth.