Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




STELLAR CHEMISTRY
Surprising new class of 'hypervelocity stars' discovered escaping the galaxy
by Staff Writers
Nashville TN (SPX) Jan 10, 2014


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. Image courtesy Julie Turner, Vanderbilt University. The top view of the galaxy comes from the National Aeronautics and Space Administration and the side view comes from the European Southern Observatory. For a larger version of this image please go here.

An international team of astronomers has discovered a surprising new class of "hypervelocity stars" - solitary stars moving fast enough to escape the gravitational grasp of the Milky Way galaxy.

The discovery of this new set of "hypervelocity" stars was described at the annual meeting of the American Astronomical Society this week in Washington, D.C., and is published in the Jan. 1 issue of the Astrophysical Journal.

"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."

The discovery came as Palladino, working under the supervision of Kelly Holley-Bockelmann, assistant professor of astronomy at Vanderbilt was mapping the Milky Way by calculating the orbits of Sun-like stars in the Sloan Digital Sky Survey, a massive census of the stars and galaxies in a region covering nearly one quarter of the sky.

"It's very hard to kick a star out of the galaxy," said Holley-Bockelmann. "The most commonly accepted mechanism for doing so involves interacting with the supermassive black hole at the galactic core. That means when you trace the star back to its birthplace, it comes from the center of our galaxy. None of these hypervelocity stars come from the center, which implies that there is an unexpected new class of hypervelocity star, one with a different ejection mechanism."

Astrophysicists calculate that a star must get a million-plus mile-per-hour kick relative to the motion of the galaxy to reach escape velocity. They also estimate that the Milky Way's central black hole has a mass equivalent to four million suns, large enough to produce a gravitational force strong enough to accelerate stars to hyper velocities. The typical scenario involves a binary pair of stars that get caught in the black hole's grip.

As one of the stars spirals in toward the black hole, its companion is flung outward at a tremendous velocity. So far, 18 giant blue hypervelocity stars have been found that could have been produced by such a mechanism.

Now Palladino and her colleagues have discovered an additional 20 sun-sized stars that they characterize as possible hypervelocity stars.

"One caveat concerns the known errors in measuring stellar motions," she 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."

The astronomers are following up with additional observations.

The new rogues appear to have the same composition as normal disk stars, so the astronomers do not think that their birthplace was in the galaxy's central bulge, the halo that surrounds it, or in some other exotic place outside the galaxy.

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

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

.


Related Links
Vanderbilt University
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





STELLAR CHEMISTRY
Massive stars mark out Milky Way's 'missing' arms
Leeds UK (SPX) Dec 23, 2013
A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA's Spitzer Space Telescope that only showed two arms. The new research, which is published online today [17 December] in the Monthly Notices of the Royal Astronomical Society, is part of the RMS Survey, which was launched by academics at the Univers ... read more


STELLAR CHEMISTRY
Wake Up Yutu

Chang'e-3 satellite payload APXS obtained its first spectrum of lunar regolith

Chang'e 3 Lander and Rover From Above

China's moon rover "sleeps" through lunar night

STELLAR CHEMISTRY
Who Wants to Go to Mars - One Way?

More than 1,000 chosen for one-way Mars reality-TV mission

One-way trip to Mars? Sign me up, says Frenchwoman

Clues from Orbit Aiding Exploration Of Opportunity Rover

STELLAR CHEMISTRY
Toymakers target 'kidults' at high-tech Hong Kong fair

Earthly politicians seek roadmap for space exploration

An astronaut's rhythm

China has world's most outbound tourists

STELLAR CHEMISTRY
China launches communications satellite for Bolivia

China's moon rover continues lunar survey after photographing lander

China's Yutu "naps", awakens and explores

Deep space monitoring station abroad imperative

STELLAR CHEMISTRY
Obama Administration Extends ISS Until at Least 2024

NASA extends space station life to 2024

New Science Bound for Station on Orbital's Cygnus

CU-Boulder to fly antibiotic experiment on ants to space station

STELLAR CHEMISTRY
Cygnus Heads to Space for First Station Resupply Mission

Orbital to attempt launch to space station Thursday

Orbital Sciences launches second mission to space station

'20 years of toil has paid off' Says Radhkrishnan

STELLAR CHEMISTRY
NASA's Kepler Provides Insights on Enigmatic Planets

Research: Smaller exoplanets found to be covered in gas

Newfound planet is Earth-mass but gassy

Planet-hunting telescope camera returns first images of exoplanets

STELLAR CHEMISTRY
3D printing poised to shake up shopping

RAMBO a small but powerful magnet

Sony unveils game service as PS4 sales top 4.2 million

S. Asia takes 71 percent of market for ship breaking




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement