Science Current Events | Science News | Brightsurf.com
 

Rogue stars ejected from the galaxy are found in intergalactic space

May 01, 2012

It's very difficult to kick a star out of the galaxy.

In fact, the primary mechanism that astronomers have come up with that can give a star the two-million-plus mile-per-hour kick it takes requires a close encounter with the supermassive black hole at the galaxy's core.

So far astronomers have found 16 of these "hypervelocity" stars. Although they are traveling fast enough to eventually escape the galaxy's gravitational grasp, they have been discovered while they are still inside the galaxy.

Now, Vanderbilt astronomers report in the May issue of the Astronomical Journal that they have identified a group of more than 675 stars on the outskirts of the Milky Way that they argue are hypervelocity stars that have been ejected from the galactic core. They selected these stars based on their location in intergalactic space between the Milky Way and the nearby Andromeda galaxy and by their peculiar red coloration.

"These stars really stand out. They are red giant stars with high metallicity which gives them an unusual color," says Assistant Professor Kelly Holley-Bockelmann, who conducted the study with graduate student Lauren Palladino.

In astronomy and cosmology, "metallicity" is a measure of the proportion of chemical elements other than hydrogen and helium that a star contains. In this case, high metallicity is a signature that indicates an inner galactic origin: Older stars and stars from the galactic fringes tend to have lower metallicities.

The researchers identified these candidates by analyzing the millions of stars catalogued in the Sloan Digital Sky Survey.

"We figured that these rogue stars must be there, outside the galaxy, but no one had ever looked for them. So we decided to give it a try," said Holley-Bockelmann, who is studying the behavior of the black hole at the center of the Milky Way galaxy.

Astronomers have now found evidence for giant black holes at the centers of many galaxies. They estimate that the Milky Way's central black hole has a mass of four million solar masses. They calculate that the gravitational field surrounding such a supermassive black hole is strong enough to accelerate stars to hypervelocities.

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 towards the black hole, its companion is flung outward at a tremendous velocity.

A second scenario takes place during periods when the central black hole is in the process of ingesting a smaller black hole. Any star that ventures too close to the circling pair can also get a hypervelocity kick.

Red giant stars are the end stage in the evolution of small, yellow stars like the Sun. So, the stars in Holley-Bockelmann's rogues' gallery should have been small stars like the Sun when they tangled with the central black hole. As they traveled outward, they continued to age until they reached the red giant stage. Even traveling at hypervelocities, it would take a star about 10 million years to travel from the central hub to the spiral's edge, 50,000 light years away.

"Studying these rogue stars can provide us with new insights into the history and evolution of our home galaxy," said Holley-Bockelmann. The researchers' next step is determine if any of their candidates are unusually red brown dwarfs instead of red giants. Because brown dwarfs produce a lot less light than red giants, they would have to be much closer to appear equally bright.

###

Heather Morrison at Case Western Reserve University, Patrick Durrell and John Feldmeier at Youngstown State University, Robin Ciardullo and Richard Wade at Pennsylvania State University, and J. Davy Kirkpatrick and Patrick Lowrance at the California Institute of California also contributed to the research, which was funded by grants from the National Science Foundation and the Department of Education's Graduate Assistance in Areas of National Need fellowship.

Vanderbilt University


Related Black Hole Current Events and Black Hole News Articles


Scientists discover how supermassive black holes keep galaxies turned off
An international team of scientists has identified a common phenomenon in galaxies that could explain why huge numbers of them turn into cosmic graveyards.

Supermassive black holes in 'red geyser' galaxies cause galactic warming
An international team of scientists, including the University of Kentucky's Renbin Yan, have uncovered a new class of galaxies, called "red geysers," with supermassive black hole winds so hot and energetic that stars can't form.

Supermassive black hole wind can stop new stars from forming
Scientists have uncovered a new class of galaxies with supermassive black hole winds that are energetic enough to suppress future star formation.

Hubble finds clues to the birth of supermassive black holes
Astrophysicists have taken a major step forward in understanding how supermassive black holes formed. Using data from Hubble and two other space telescopes, Italian researchers have found the best evidence yet for the seeds that ultimately grow into these cosmic giants.

NASA scientist suggests possible link between primordial black holes and dark matter
Dark matter is a mysterious substance composing most of the material universe, now widely thought to be some form of massive exotic particle.

Astrophysicists from the IAC discover an intense wind in the neighborhood of a black hole
V404 Cygni is a black hole within a binary system located in the constellation of Cygnus. In such systems, of which less than 50 are known, a black hole of around 10 times the mass of the Sun is swallowing material from a very nearby star, its companion star.

Hubble spies a spiral snowflake
Together with irregular galaxies, spiral galaxies make up approximately 60 percent of the galaxies in the local universe.

Intense wind found in the neighborhood of a black hole
An international team of astrophysicists, including Professor Phil Charles from the University of Southampton, have detected an intense wind from one of the closest known black holes to the Earth.

UCI astronomers determine precise mass of a giant black hole
Astronomers from the University of California, Irvine and other universities have derived a highly precise measurement of the mass of a black hole at the center of a nearby giant elliptical galaxy.

NASA's Fermi Telescope helps link cosmic neutrino to blazar blast
Nearly 10 billion years ago, the black hole at the center of a galaxy known as PKS B1424-418 produced a powerful outburst. Light from this blast began arriving at Earth in 2012.
More Black Hole Current Events and Black Hole News Articles

Black Hole (Pantheon Graphic Novels)

Black Hole (Pantheon Graphic Novels)
by Charles Burns (Author)


Winner of the Eisner, Harvey, and Ignatz Awards

The setting: suburban Seattle, the mid-1970s. We learn from the outset that a strange plague has descended upon the area’s teenagers, transmitted by sexual contact. The disease is manifested in any number of ways — from the hideously grotesque to the subtle (and concealable) — but once you’ve got it, that’s it. There’s no turning back.

As we inhabit the heads of several key characters — some kids who have it, some who don’t, some who are about to get it — what unfolds isn’t the expected battle to fight the plague, or bring heightened awareness to it , or even to treat it. What we become witness to instead is a fascinating and eerie portrait of the nature of high school alienation itself — the savagery,...

Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved

Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved
by Marcia Bartusiak (Author)


The contentious history of the idea of the black hole—the most fascinating and bizarre celestial object in the heavens

For more than half a century, physicists and astronomers engaged in heated dispute over the possibility of black holes in the universe. The weirdly alien notion of a space-time abyss from which nothing escapes—not even light—seemed to confound all logic. This engrossing book tells the story of the fierce black hole debates and the contributions of Einstein and Hawking and other leading thinkers who completely altered our view of the universe.

Renowned science writer Marcia Bartusiak shows how the black hole helped revive Einstein’s greatest achievement, the general theory of relativity, after decades during which it had been pushed into the...

Death by Black Hole: And Other Cosmic Quandaries

Death by Black Hole: And Other Cosmic Quandaries
by Neil deGrasse Tyson (Author)


“[Tyson] tackles a great range of subjects . . . with great humor, humility, and―most important― humanity.” ―Entertainment Weekly Loyal readers of the monthly "Universe" essays in Natural History magazine have long recognized Neil deGrasse Tyson's talent for guiding them through the mysteries of the cosmos with clarity and enthusiasm. Bringing together more than forty of Tyson's favorite essays, ?Death by Black Hole? explores a myriad of cosmic topics, from what it would be like to be inside a black hole to the movie industry's feeble efforts to get its night skies right. One of America's best-known astrophysicists, Tyson is a natural teacher who simplifies the complexities of astrophysics while sharing his infectious fascination for our...

Black Holes: A Very Short Introduction (Very Short Introductions)

Black Holes: A Very Short Introduction (Very Short Introductions)
by Katherine Blundell (Author)


Black holes are a constant source of fascination to many due to their mysterious nature. This Very Short Introduction, addresses a variety of questions, including what a black hole actually is, how they are characterized and discovered, and what would happen if you came too close to one.

Professor Katherine Blundell looks at the seemingly paradoxical, mysterious, and intriguing phenomena of black holes. Outlining their nature and characteristics, both those resulting from the spectacular collapse of heavy stars, and the giant black holes found at the centres of galaxies, she separates scientific fact from science fiction, and demonstrates the important role they play in the cosmos.

ABOUT THE SERIES:
The Very Short Introductions series from Oxford University Press contains...

Black Holes and Time Warps: Einstein's Outrageous Legacy (Commonwealth Fund Book Program)

Black Holes and Time Warps: Einstein's Outrageous Legacy (Commonwealth Fund Book Program)
by Kip S. Thorne (Author), Stephen Hawking (Foreword)


Ever since Albert Einstein's general theory of relativity burst upon the world in 1915 some of the most brilliant minds of our century have sought to decipher the mysteries bequeathed by that theory, a legacy so unthinkable in some respects that even Einstein himself rejected them. Which of these bizarre phenomena, if any, can really exist in our universe? Black holes, down which anything can fall but from which nothing can return; wormholes, short spacewarps connecting regions of the cosmos; singularities, where space and time are so violently warped that time ceases to exist and space becomes a kind of foam; gravitational waves, which carry symphonic accounts of collisions of black holes billions of years ago; and time machines, for traveling backward and forward in time.

...

Black Holes: Everything You Need to Know About Black Holes and Black Hole Physics (space exploration, space, astronomy, Cosmology)

Black Holes: Everything You Need to Know About Black Holes and Black Hole Physics (space exploration, space, astronomy, Cosmology)



Everything you Need to Know about Black Holes and Black Hole Physics!

Black Holes have been, and are still to this day, one of the great mysteries of cosmology. They have inspired the imaginations of generations when looking out into space and have been the focus of astronomy for years. Today, much is known about black hole physics and the characteristics of these great beasts of space. This book will bring you up to speed with what we know today about black holes.


Here Is A Preview Of What You'll Learn...Black Hole FundamentalsBlack Hole HistoryBlack Hole FormationBlack Hole AnatomyEvent HorizonSpace and TimeEntering a Black HoleCosmology and AstronomySchwarzschild RadiusPrimordial Black HoleSupermassive Black HoleStellar Black HoleSingularityPhoton...

Black Hole Blues and Other Songs from Outer Space

Black Hole Blues and Other Songs from Outer Space
by Janna Levin (Author)


The authoritative story of the headline-making discovery of gravitational waves—by an eminent theoretical astrophysicist and award-winning writer.


From the author of How the Universe Got Its Spots and A Madman Dreams of Turing Machines, the epic story of the scientific campaign to record the soundtrack of our universe.
 
Black holes are dark. That is their essence. When black holes collide, they will do so unilluminated. Yet the black hole collision is an event more powerful than any since the origin of the universe. The profusion of energy will emanate as waves in the shape of spacetime: gravitational waves. No telescope will ever record the event; instead, the only evidence would be the sound of spacetime ringing. In 1916, Einstein predicted the existence of...

Black Holes (True Books: Space (Paperback))

Black Holes (True Books: Space (Paperback))
by Ker Than (Author)


- Clean new design for easy readability and comprehension
- Updated text presented in a lively, continuous narrative
- New center-spread "sidebar" feature presenting material in a fun, creative way
- Excellent age-appropriate introduction to curriculum-relevant subjects
- "Important Words" glossary clarifies subject-specific vocabulary
- "Resources" section encourages independent study
- Index makes navigating subject matter easy

Black Holes and Baby Universes and Other Essays

Black Holes and Baby Universes and Other Essays
by Stephen W. Hawking (Author)


NEW YORK TIMES BESTSELLER

THIRTEEN EXTRAORDINARY ESSAYS SHED NEW LIGHT ON THE MYSTERIES OF THE UNIVERSE—AND ON ONE OF THE MOST BRILLIANT THINKERS OF OUR TIME.
 
In his phenomenal bestseller A Brief History of Time, Stephen Hawking literally transformed the way we think about physics, the universe, reality itself. In these thirteen essays and one remarkable extended interview, the man widely regarded as the most brilliant theoretical physicist since Einstein returns to reveal an amazing array of possibilities for understanding our universe.

Building on his earlier work, Hawking discusses imaginary time, how black holes can give birth to baby universes, and scientists’ efforts to find a complete unified theory that would predict everything in the universe. With his...

A Black Hole Is Not a Hole

A Black Hole Is Not a Hole
by Carolyn Cinami DeCristofano (Author), Michael Carroll (Illustrator)


Get ready to S-T-R-E-T-C-H your mind!

What is a black hole? Where do they come from? How were they discovered? Can we visit one? Carolyn Cinami DeCristofano takes readers on a ride through the galaxies (ours, and others), answering these questions and many more about the phenomenon known as a black hole.

In lively and often humorous text, the book starts off with a thorough explanation of gravity and the role it plays in the formation of black holes. Paintings by Michael Carroll, coupled with real telescopic images, help readers visualize the facts and ideas presented in the text, such as how light bends, and what a supernova looks like.

A BLACK HOLE IS NOT A HOLE is an excellent introduction to an extremely complex scientific concept. Back matter includes a timeline...

© 2016 BrightSurf.com