Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



STELLAR CHEMISTRY
Who stole all the stars
by Staff Writers
Melbourne, Australia (SPX) Oct 14, 2016


File image.

Investigating the millions of missing stars from the centres - or cores - of two big galaxies, astronomers at Swinburne University of Technology say they may have solved this cosmic whodunit, and the main culprits are not the usual suspects.

While the scientists confirm that one of the depleted cores is the largest ever detected, they report that it may not have formed in the manner previously thought.

In normal sized galaxies, the density of stars increases smoothly as you move towards their centre. However, for decades astronomers have observed a star shortage in the centres of many big galaxies.

"The smaller of the two galaxies that we examined - the one with the smaller depleted core - likely formed from the collision of two similar galaxies, each seeded with a massive black hole several billion times the mass of our Sun," says lead-author Dr Paolo Bonfini, now at the Universidad Nacional Autonoma de Mexico.

"In this well studied process, the black holes migrate towards the centre of the newly-forged galaxy by ousting the stars already there, hurling them outward in a gravitational sling-shot manoeuvre. Pairs of massive black holes effectively work together and gang up on individual stars in a galaxy's core."

Co-author of the study, Swinburne's Professor Alister Graham, says even less fortunate stars that venture too close to either black hole can be torn apart and swallowed.

"These cataclysmic events produce high-energy UV and X-ray flares as we briefly see into a star's hot interior while it is shredded by the immense gravitational field around each black hole. When the black holes themselves finally merge, a series of gravitational waves are also emitted," says Professor Graham.

However, simulations have shown that if a galaxy collision involves a larger galaxy consuming a smaller satellite galaxy, then things can be different.

If the captured galaxy has a densely crowded centre of its own, then this tightly bound region can survive largely intact during the cannibalistic affair, with only the outer stars stripped-off.

"The captured galaxies move towards the centre of the large galaxy in a braking process that pumps stars out of the core of the large galaxy," says Professor Ben Moore, galaxy modeler and Director at the University of Zurich's Center for Theoretical Astrophysics and Cosmology in Switzerland.

"Simulations have shown that they do this in such a way that a core of constant stellar density is created, around which the semi-digested satellites then hover."

Unlike the smaller of the two galaxies studied by the scientists, the stars in the core of the bigger galaxy are uniform in their distribution and this galaxy also contains several dense knots of stars near the edge of its core.

One of these `knots' is a whopping 45 billion times the mass of our Sun - nearly the entire stellar mass of our own Milky Way galaxy - and therefore capable of causing a lot of damage.

Furthermore, the larger galaxy's giant core, discovered in 2012 by Marc Postman at the Space Telescope Science Institute in the USA, is unusual in that it is some ten times larger than those typically observed in other big galaxies.

"We suspect that this giant core primarily formed from captured satellite galaxies, rather than massive black holes," Professor Graham says. "Indeed, the culprits appear to have quite literally been caught in the act."

The bigger galaxy, known as 2MASX J17222717+3207571, is 75 times more massive than the Milky Way, and it is the brightest amid a large cluster of galaxies in the direction of the Hercules Constellation. The smaller galaxy with the smaller core, known as 2MASX J09194427+5622012, is about 30 times the mass of the Milky Way and is near the Ursa Major constellation. Both galaxies are roughly 4 billion light years away.

This research helps to open a new window on the study of galaxy cores and the processes that shape the evolution of massive galaxies. The future James Webb Space Telescope, expected to be launched in 2018, will enable astronomers to better image more galaxy cores and hopefully reveal how often hapless satellite galaxies are consumed.

This research has been published in The Astrophysical Journal.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Swinburne University of Technology
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

Previous Report
STELLAR CHEMISTRY
Discovery of an extragalactic hot molecular core
Sendai, Japan (SPX) Oct 12, 2016
Astronomers have discovered a 'hot molecular core,' a cocoon of molecules surrounding a newborn massive star, for the first time outside our Galaxy. The discovery, which marks the first important step for observational studies of extragalactic hot molecular cores and challenges the hidden chemical diversity of our universe, appears in a paper in The Astrophysical Journal Volume 827. The sc ... read more


STELLAR CHEMISTRY
Spectacular Lunar Grazing Occultation of Bright Star on Oct. 18

Small Impacts Are Reworking Lunar Soil Faster Than Scientists Thought

A facelift for the Moon every 81,000 years

Hunter's Supermoon to light up Saturday night sky

STELLAR CHEMISTRY
Ready for the Red Planet

What! - Go To Mars?

Modeling floods that formed canyons on Earth and Mars

NASA's MAVEN Mission Gives Unprecedented Ultraviolet View of Mars

STELLAR CHEMISTRY
Beaches, skiing and tai chi: Club Med, Chinese style

NASA begins tests to qualify Orion parachutes for mission with crew

New Zealand government open-minded on space collaboration

Growing Interest: Students Plant Seeds to Help NASA Farm in Space

STELLAR CHEMISTRY
China closer to establishing permanent space station

Ambitious space satellite projects set for liftoff

China to enhance space capabilities with launch of Shenzhou-11

China launches 2 astronauts for 33-day mission

STELLAR CHEMISTRY
Tools Drive NASA's TReK to New Discoveries

Hurricane Nicole delays next US cargo mission to space

Automating sample testing thanks to space

Orbital CRS-5 launching hot and bright science to space

STELLAR CHEMISTRY
US-Russia Standoff Leaves NASA Without Manned Launch Capabilities

Swedish Space Corporation Celebrates 50th Anniversary of Esrange Space Center

Ariane 5 ready for first Galileo payload

More commercial spaceports going ahead

STELLAR CHEMISTRY
Proxima Centauri might be more sunlike than we thought

Stars with Three Planet-Forming Discs of Gas

TESS will provide exoplanet targets for years to come

The death of a planet nursery?

STELLAR CHEMISTRY
Mars astronauts face chronic dementia risk from cosmic ray exposure

U.S. State Dept. approves $194 million radar sale to Kuwait

Lego-like wall produces acoustic holograms

Efficiency plus versatility




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






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news 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. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. 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