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By Jeff Austin
When biologists or chemists need to test a hypothesis, they have an endless variety of lab equipment and substances with which to conduct research. But how do astrophysicists experiment on a star?
In the case of Richard H. Durisen, professor of astronomy at IUB, one solution borrows technology from the world of motion picture and television special effects. Using a Silicon Graphics workstation and specialized software, Durisen and his colleagues are creating and analyzing three-dimensional models of newborn stars generated by complex computer calculations.
Stars are born when huge gas clouds are compressed by gravity. The gases form a rapidly rotating disk around a central "protostar." It was from such a disk spinning around the sun that the earth and other planets formed.
Until the 1980s, astrophysicists could only analyze star formation in terms of lengthy equations that were difficult to solve with pencil and paper. Then, supercomputers like the Cray Y-MP made it possible to calculate the behavior of protostellar gas disks and animate the results.
Now, calculations that once required a supercomputer are being carried out on the fourth floor of Swain Hall West in the Astronomy Department's new Remote Observing Station and Scientific Visualization Lab. The facility has been operating for about two months and was funded by the National Science Foundation with matching funds from IU Research and the University Graduate School.
"It's really quite remarkable," Durisen said. "We can now do those calculations we were doing on a Cray on a workstation. It's not as fast as a Cray, but it's our own machine, so we can dedicate much more time to doing what we do. We're really quite a lot farther along now in terms of the size of the computational grid we can use and the complexity of the physics of the object under examination"
Currently, Durisen and his colleagues are the only researchers in the world who employ fully three-dimensional models, including data for the central star, the star/disk boundary and the disk outer boundary.
If printed out, the calculations for the models would fill the average high school library. The process of calculating data for every part of the star and disk is more painstaking, but yields a simulation that more closely resembles what actually occurs when a star forms.
Essential to the success of the project is doctoral candidate Robert Link, who was hired as a research assistant through Durisen's NASA grant from the "Origins of the Solar System" program. Link has taken on much of the responsibility for generating the computer animations in addition to his own doctoral work.
"I started working with Professor Durisen before I had a doctoral project," said Link, who is also working with Michael Pierce, assistant professor of astronomy at IUB, on questions surrounding the expansion of the universe. "I had a class with Professor Durisen my first semester here, and we got along pretty well. So, when I needed someone to help me with 'getting my feet wet' in research, I went to him. Working on star formation has taught me a number of skills I've been able to use in my own research."
In recognition of his expertise in star formation theory, Durisen recently received a research award from the Alexander von Humboldt Foundation and the Federal Republic of Germany. The award provides foreign scholars the opportunity to further their research at German institutions during visits of up to a year.
"Interestingly, though," he said, "one of my first projects when I visit Germany will be a paper and pencil project, not a computer simulation. I will be working with the director of the Max Planck Institute for Extraterrestrial Physics on formation theory for certain types of meteorites. While I'm there, near Munich, I will certainly also take advantage of their resources to continue my work on hydrodynamic simulations of these rotating gas disks and on simulations of the effects of meteoroid bombardment on Saturn's rings."