“Hypervelocity stars” have more speed than our galaxy

Top and side views of the Milky Way galaxy show the location of four of the new class of hypervelocity stars. These are sun-like stars that are moving at speeds of more than a million miles per hour relative to the galaxy: fast enough to escape its gravitational grasp. The general directions from which the stars have come are shown by the colored bands. (Graphic design by Julie Turner, Vanderbilt University. Top view courtesy of the National Aeronautics and Space Administration. Side view courtesy of the European Southern Observatory.)
Top and side views of the Milky Way galaxy show the location of four of the new class of hypervelocity stars. These are sun-like stars that are moving at speeds of more than a million miles per hour relative to the galaxy: fast enough to escape its gravitational grasp. The general directions from which the stars have come are shown by the colored bands. (Graphic design by Julie Turner, Vanderbilt University. Top view courtesy of the National Aeronautics and Space Administration. Side view courtesy of the European Southern Observatory.)

Main Point:

Scientists have found a new class of stars in universe, dubbed as “hypervelocity stars” moving with such a high speed that they are out of gravitational grip of the Milky Way galaxy.

Published in:

Astrophysical Journal

Study Further:

Our universe is full of stars and usually, the stars come from the center of our galaxy. However, these new types of stars are not found to come from the center of our galaxy.

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

Astronomers have found 20 sun-sized stars that are possible hypervelocity stars. These stars are moving with the speed of more than a million miles per hour relative to the galaxy helping them to be not in control of the gravitational power of galaxy.

“One caveat concerns the known errors in measuring stellar motions,” Kelly Holley-Bockelmann, assistant professor of astronomy at Vanderbilt, said. “To get the speed of a star, you have to measure the position really accurately over decades. If the position is measured badly a few times over that long time interval, it can seem to move a lot faster than it really does. We did several statistical tests to increase the accuracy of our estimates. So we think that, although some of our candidates may be flukes, the majority are real.”

Astronomers have presented the recent finding of “hypervelocity” stars at the annual meeting of the American Astronomical Society this week in Washington, D.C.

Research Suggestion:

“The big question is: what boosted these stars up to such extreme velocities? We are working on that now,” said Holley-Bockelmann.

Sources:

Surprising new class of “hypervelocity stars” discovered escaping the galaxy – Vanderbilt University (http://goo.gl/0WUdBm)

Lauren E. Palladino et al. (2014). HYPERVELOCITY STAR CANDIDATES IN THE SEGUE G AND K DWARF SAMPLE The Astrophysical Journal DOI: 10.1088/0004-637X/780/1/7

Usman Zafar Paracha

Usman Zafar Paracha is Assistant Professor, Pharmaceutics, in Hajvery University, Lahore, Pakistan.