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RAS PN09/37 (NAM24): "Pillars of Creation" Formed in the Shadows

Last Updated on Thursday, 23 April 2009 18:59
Published on Thursday, 23 April 2009 00:00
607px_Eagle_nebula_pillars.jpgResearch by astronomers at the Dublin Institute of Advanced Studies suggests that shadows hold the key to how giant star-forming structures like the famous “Pillars of Creation” take shape.  The pillars are dense columns within giant clouds of dust and gas where massive stars form.  Several theories have been proposed to explain why the pillars develop around the edge of ionised gas bubbles surrounding young, very hot stars. Using computer models, the Dublin group has found that partially-shadowed clumps of gas tend to creep towards darker areas, causing pile-ups behind dense knots of gas and dust that screen the intense ultraviolet light emitted by the stars.
Jonathan Mackey, who is presenting the results at the European Week of Astronomy and Space Science in Hatfield said, “We created a simulation with a random distribution of lots of dense clouds with different sizes and shapes.  We found that in certain cases a number of clouds can merge together in the shadows to form structures that look very like observed pillars.  They are sufficiently dense to match the observations, can form in about 150 000 years and can survive for about 100 000 years.  Although this is a preliminary study, we believe our results are quite robust and will be confirmed by more detailed modelling.”

The team, led by Dr Andrew Lim, found that the configuration of clumps of gas had to be favourable for the pillars to form.  Some age estimates put the Eagle Nebula pillars at no more than 100 000 years old, and models show that the shadow from a single clump would not attain the density to form a pillar in that relatively short timescale.

“Many of our models do not produce pillars that are as long and narrow as those in the Eagle Nebula, at least not at the observed gas density.  It needs the right configuration of dense clumps of gas to form a long pillar.  Unless the shadowed region is already very dense to begin with, it just takes too long to collect and organise the gas into a pillar,” said Lim.

The group plans to add increasing levels of realism to the model over the next couple of years, bringing in more accurate representations of the complex chemistry of interstellar gas, the effects of radiation from diffuse sources.  Adding in the effects of gravity will also be important as the pillars contain dense gas condensations which are in the process of collapsing under their own weight to form the next generation of stars.
Mackey said, "Gravity is relatively unimportant when the pillars are forming, but there comes a point when they get very dense and it cannot be ignored any longer.  We plan to include gravitation in future work so that we can study the next generation of stars which are forming in the pillars."

IMAGES:
Images can be found at:
http://www.dias.ie/elephant/index.html

NOTES FOR EDITORS

THE EUROPEAN WEEK OF ASTRONOMY AND SPACE SCIENCE
More than 1000 astronomers and space scientists will gather at the University of Hertfordshire for the European Week of Astronomy and Space Science (EWASS), incorporating the 2009 Royal Astronomical Society National Astronomy Meeting (RAS NAM 2009) and the European Astronomical Society Joint Meeting (JENAM 2009). The meeting runs from 20th to 23rd April 2009.
 
EWASS is held in conjunction with the UK Solar Physics (UKSP) and Magnetosphere Ionosphere and Solar-Terrestrial Physics (MIST) meetings. The conference includes scientific sessions organised by the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) and the European Space Agency (ESA).
EWASS is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Hertfordshire, Hatfield.
THE ROYAL ASTRONOMICAL SOCIETY

The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.

CONTACTS:

Jonathan Mackey
Dublin Institute for Advanced Studies,
31 Fitzwilliam Place
Dublin 2, Ireland.
Tel: +353-86-0509310
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Andrew Lim
Dublin Institute for Advanced Studies,
31 Fitzwilliam Place
Dublin 2, Ireland.
E-mail:  This email address is being protected from spambots. You need JavaScript enabled to view it.