Subscribe free to our newsletters via your
. 24/7 Space News .




STELLAR CHEMISTRY
Riddle of Galactic Thin-Thick Disk Solved
by Staff Writers
Potsdam, Germany (SPX) Apr 30, 2015


The Milky Way analog galaxy, NGC 891. Overlaid are color curves that show the flares from groups of stars with similar ages. When all stars are put together, the disk has constant thickness, shown by the straight white lines. Image courtesy Adam Block, Mt. Lemmon SkyCenter, University of Arizona / Ivan Minchev, AIP. For a larger version of this image please go here.

A long-standing puzzle regarding the nature of disk galaxies has finally been solved by a team of astronomers led by Ivan Minchev from the Leibniz Institute for Astrophysics Potsdam (AIP), using state-of-the-art theoretical models.

The new study shows that groups of stars with the same age always flare as the result of massive galactic collisions. When taken all together, these flares, nested like the petals of a blooming rose, puff up the disk and constitute what astronomers call the "thick" disk.

"We were able to show for the first time that galactic thick disks are not composed only of old stars but must also contain young stars at larger distances from the galactic center," explains Minchev.

"The flaring seen in groups of stars with the same age is caused mostly by the bombardment of small satellite galaxies. These cosmological car crashes pummel the young disk and cause it to swell and flare. "

To arrive at this new result, the team ran numerical simulations on massive super computers and examined the structure of their simulated galaxies. The scientists grouped stars by common age and looked at where they were located. What they found was that stars of a given age group constituted a disk with flared edges, much like the mouth of a trumpet.

This flaring is unavoidable, being caused when the main galaxy collides with smaller galaxies - a generic feature of how scientists believe galaxies form. Since the oldest stars formed in the inner region of the galaxy, for them this flaring occurs closer to the center, while for the younger stars it occurs at the periphery of the galaxy. When put together, the combination of flaring from all the stars produces the elusive thick disk, as observed.

One of the most fascinating aspects of galaxies is that their stars can be separated into two components: a fluffy thick disk that enshrouds a thin disk. Until now the understanding has been that stars in the thick disk were the oldest. In observations of the Milky Way the oldest stars are found to be closer to the center, while younger stars are more extended.

Scientists agree that this separation is likely due to an "inside-out" formation scenario, wherein the Milky Way forms stars first in its center and later in its outer region, much like how cities grow radially from a medieval center to modern suburbs.

Observing the structure of the Milky Way is tricky, since we are located within its disk, roughly half way from the center. Instead, astronomers have to rely on the stars that surround us and build a model from this limited perspective.

Nevertheless, if the Milky Way were similar to other galaxies and its thick disk were composed only of old, centrally concentrated stars, then one would naively expect its thick disk to be short. But in other galaxies the thick disks are observed to be as extended as the galaxies themselves. Minchev's results resolve this contradiction by requiring that thick disk stars become younger in the disk outskirts.

"With our new understanding of the formation of, and interplay between, galactic thin and thick disks, we have moved much closer to solving one of the most fundamental problems of Galactic astrophysics.," concludes Ivan Minchev.

"Our predictions will soon be tested with data from the Gaia space mission and using high precision instruments, such as MUSE on the Very Large Telescope."


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
Astrophysics Potsdam
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








STELLAR CHEMISTRY
Water could have been abundant in the first billion years
Boston MA (SPX) Apr 29, 2015
How soon after the Big Bang could water have existed? Not right away, because water molecules contain oxygen and oxygen had to be formed in the first stars. Then that oxygen had to disperse and unite with hydrogen in significant amounts. New theoretical work finds that despite these complications, water vapor could have been just as abundant in pockets of space a billion years after the Big Bang ... read more


STELLAR CHEMISTRY
Russia Invites China to Join in Creating Lunar Station

Japan to land first unmanned spacecraft on moon in 2018

Dating the moon-forming impact event with meteorites

Japan to land probe on the moon in 2018

STELLAR CHEMISTRY
Rover on the Lookout for Dust Devils

UAE opens space center to oversee mission to Mars

Robotic Arm Gets Busy on Rock Outcrop

Mars might have liquid water

STELLAR CHEMISTRY
The Mysteries of Astronautics

General Dynamics Integrates NASA's SGSS Infrastructure

India Role Model in Space Science Benefiting Common Man

Space law is no longer beyond this world

STELLAR CHEMISTRY
Xinhua Insight: How China joins space club?

Chinese scientists mull power station in space

China completes second test on new carrier rocket's power system

China's Yutu rover reveals Moon's "complex" geological history

STELLAR CHEMISTRY
Progress Incident Not Threatening Orbital Station, Work of Crew

Russia loses control of unmanned spacecraft

Japanese astronaut to arrive in ISS in May

Liquid crystal bubbles experiment arrives at International Space Station

STELLAR CHEMISTRY
Ariane 5 gives dual lift" to the THOR 7 and SICRAL 2 satellites

Ariane 5's first launch of 2015

Sentinel-2A payload processing begins for Vega launch in June

45th Space Wing successfully launches first-ever Turkmenistan satellite

STELLAR CHEMISTRY
Titan's Atmosphere Useful In Study Of Hazy Exoplanets

Tau Ceti Probably not the next Earth

Astronomers join forces to speed discovery of habitable worlds

Robotically discovering Earth's nearest neighbors

STELLAR CHEMISTRY
Fast and accurate 3-D imaging technique to track optically trapped particles

Mechanical cloaks of invisibility - without complicated mathematics

ASC Signal To Supply Globecomm With Earth Stations and Upgrades

Reducing big data using quantum theory




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - 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. 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 All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.