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




Subscribe to our free daily newsletters



From Galaxy Collisions To Star Birth: ISO Finds The Missing Link

This picture shows the colliding galaxies known as Antennae (NGC4038/4039) located 60 million light years away in the constellation Corvus. Data from ESA's Infrared Space Observatory (ISO) have provided the first direct evidence that shock waves genarated by the collision excite the gas and create the right conditions for star formation. The excited gas is observed in the overlapping region (enclosed within the white dashed lines). New stars will be born there and in the course of the next million year they will make the Antennae galaxies twice as bright in the infrared. Credits: HST image, ESA/NASA.
Paris (ESA) Mar 30, 2005
Data from ISO, the infrared observatory of the European Space Agency (ESA), have provided the first direct evidence that shock waves generated by galaxy collisions excite the gas from which new stars will form.

The result also provides important clues on how the birth of the first stars was triggered and speeded up in the early Universe.

By observing our galaxy and others, scientists have long concluded that the explosion of massive stars like supernovae generates shock waves and 'winds' that travel through and excite the surrounding gas clouds.

This process triggers the collapse of nearby gas that eventually leads to the birth of new stars, like a domino effect.

The signature of this process is the radiation emitted by molecular hydrogen. When hydrogen molecules are 'excited' by the energy of a nearby explosion, they emit a distinctive type of radiation that can be detected in the infrared.

This type of radiation is also observed in places where galaxies have collided with one another and the formation of new stars goes at a very high rate.

So far, however, there was no clear picture of what happens in the time between the collision of two galaxies and the birth of the first new stars.

The missing link has now been found by a team of German astronomers that have analysed ISO data of the galaxy pair nicknamed the 'Antennae' (NGC 4038/4039).

These two galaxies, located 60 million light-years away in the constellation 'Corvus' (the Crow), are currently at an early stage of encounter.

The scientists noticed that the overlapping region of the two colliding galaxies is very rich in molecular hydrogen, which is in an excited state.

In particular, the radiation from molecular hydrogen is evenly strong in the northern and southern areas of the overlap region.

Much to the team's surprise, however, there are too few supernova explosions or regions of intense star formation there to explain the observed molecular hydrogen emission.

So, the excitation of the molecular hydrogen must be the signature of that observationally rare pre-star birth phase in which hydrogen is excited by the mechanical energy produced in the collision and transported by shock waves.

In other words, these results provide the first direct evidence of the missing link between gas collision and the birth of the first stars.

The team estimates that when the gas will collapse to form new stars, during the next million years, the Antennae galaxy will become at least two times brighter in the infrared.

The astronomers believe that star formation induced by shocks may have played a role in the evolution of proto-galaxies in the first thousand million years of life of our Universe.

Shock waves produced through the collision of proto-galaxies may have triggered the condensation process and speeded-up the birth of the very first stars.

These objects, made up of only hydrogen and helium, would otherwise have taken much longer to form, since light elements such as hydrogen and helium take a long time to cool down and condense into a proto-star.

Shock waves from the first cloud collisions may have been the helping hand.

Related Links
ISO
ISO major achievements
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

Born Again Sols Could Bring Life Again To Dying Stellar Systems
Washington DC (SPX) Mar 29, 2005
Dying stars may warm previously frozen worlds around them to the point where liquid water temperature exists long enough for life to form, according to a new analysis of the evolution of habitable zones around stars by an international team of astronomers.



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






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 1995-2016 - 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.