Discovered a New class of runaway hypervelocity stars

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Washington, Jan 10: An international team of astronomers has discovered “hypervelocity stars”, a new class of solitary runaway stars as described at the annual meeting of the American Astronomical Society in Washington, D.C., this week and is published in Astrophysical Journal.

“These new hypervelocity stars are very different from the ones that have been discovered previously,” Vanderbilt University graduate student Lauren Palladino, lead author on the study, said.

“The original hypervelocity stars are large blue stars and appear to have originated from the galactic center. Our new stars are relatively small, about the size of the Sun, and the surprising part is that none of them appear to come from the galactic core,” Palladino said.

“It’s very hard to kick a star out of the galaxy,” said Kelly Holley-Bockelmann, assistant professor of astronomy at Vanderbilt .

The first outcast star was found in 2005. Another two were discovered in 2006. In 2010 using NASA’s Hubble Space Telescope reported,  HE 0437-5439 – a hyper-velocity star.

These solitary stars are moving at a speed that can gradually make them escape the gravitational hold of the Milky Way galaxy.

Palladino, was functioning under the supervision of Kelly Holley-Bockelmann. Palladino and team were working on a project called Sloan Digital Sky Survey, when they ventured upon the new class of stars. The survey purposes at studying stars and galaxies covering a quarter of the sky.

The distinctive set-up contains a binary pair of stars that get trapped in the black hole’s clutch. When one of the stars coils in near the black hole, its cohort hurl outward at an incredible velocity. Till now, 18 giant blue hypervelocity stars have been found that could have been produced by such a mechanism.

According to scientists, for a star to reach the escape velocity it needs a million above mile per hour kick comparative to the motion of the galaxy. The black hole’s mass is corresponding to four million suns, which wields a lot of gravitational force and is adequate to accelerate stars to hypervelocities.

Katharine Schlesinger from the Australian National University, Timothy Beers from the National Optical Astronomy Observatory in Tucson, Carlos Allende Prieto, Universidad de La Laguna, Spain, Young Sun Lee from New Mexico State University and Donald Schneider, Pennsylvania State University also were part of the discovery.