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Steve Kawaler, Physics and Astronomy, (515) 294-9728
Skip Derra, News Service, (515) 294-4917
ASTRONOMICAL NETWORKS USE EARTH AS A TELESCOPE
AMES, Iowa Astronomers, always looking for larger, more-powerful telescopes to peer into the skies with, are now using the Earth itself as a telescope platform.
By connecting several individual observatories via communications networks like the Internet, astronomers have been successful in using the connected telescopes as a single instrument the size of Earth, says Steve Kawaler, professor of physics and astronomy at Iowa State University. Doing this has not only breathed new life into observatories, but also has led to unprecedented views of astronomical objects.
Kawaler will describe the international astronomical efforts of the Whole Earth Telescope (WET) at the 2001 American Association for the Advancement of Science meeting in San Francisco, Feb. 15-20. Kawaler's presentation is part of the symposium, "A Telescope the Size of Earth: Global Astronomy Networks," which will be 9 a.m.-12 noon, Feb. 18. Kawaler helped organize the symposium with fellow ISU astronomer Lee Anne Willson.
Symposium speakers will make presentations on several worldwide observing efforts. Through cooperation of astronomical teams across the globe, several efforts have been underway including a survey of the entire sky, 24-hour observational coverage of a single astronomical object and very- long-baseline interferometry for high spatial resolution in the radio region of the spectrum.
The WET is both special and typical of these collaborations, which must cut through geographical and political barriers, said Kawaler, WET director. The WET is a network of 29 small- to medium-sized optical observatories in dozens of countries ranging from Austria to Chile, China and the United States. It is headquartered at Iowa State University.
"By linking these telescopes together," Kawaler said, "we can monitor astronomical objects in ways that were simply not possible before. We can learn more about these objects because we can monitor them around the clock, essentially using Earth's rotation and turning on and off observatories as they come into and pass out of the viewing area of an object."
"The WET basically is astronomy via the web," Kawaler added. "Through the use of the Internet we can have observational data from virtually anywhere in the world sent to us for analysis and interpretation."
Kawaler uses white dwarf star observations with the WET as an example of the unique capabilities of such a collaboration. White dwarf stars represent the final phase of the life of a star like our Sun. Studying white dwarfs not only allows astronomers to study what will happen to the Sun and solar system, but also show astronomers the physics of matter under extreme conditions. Through WET observations, astronomers can probe the interiors of white dwarfs and other stars through the new science of stellar seismology.
"Certain stars undergo natural vibrations that can be detected with sensitive time-series photometry and/or spectroscopy," Kawaler said. "Since the signal we seek is an unbroken time-series to allow determination of the vibration frequencies, data from a single-site is usually incapable of uniquely identifying the pulsation modes, no matter how large the telescope being used.
"In many cases, observational goals can be achieved using smaller telescopes in well-coordinated global networks," Kawaler said. "These networks can provide extended monitoring of target stars continuously for days to weeks."
Over the years, WET has observed dozens of stars in 20 separate observing campaigns, Kawaler added. Among the more interesting subjects is a star (BPM 37093) that could be made up of crystalline carbon and oxygen.
Another important project involves a pair of stars (PG 1336) that orbit each other 10 times a day and are separated from each other only by a bit more than the distance of the Earth to the moon (roughly 230,000 miles). One of those two stars also vibrates quickly, giving astronomers a way to study how this system was formed and hinting as to what its future might hold.
"Above all, perhaps, the WET demonstrates how the pursuit of science can transcend political and cultural boundaries," Kawaler said. "International cooperation doesn't only have to be a response to a global crisis, but also can be for the joy of discovery."
Ames, Iowa 50011, (515) 294-4111
Published by: University Relations,
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