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03/28/94

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Telescope groundbreaking boost to astronomy program

STANFORD -- After years of borrowing time from other institution's telescopes or analyzing data collected by others, Stanford astronomers finally are getting a large telescope they can call their own.

Stanford's share of the project may only be 10 percent, or about 25 observing nights a year. And the telescope itself may be over 1,200 miles away in west Texas. Nonetheless, the scientists are elated.

"This vaults us into the big leagues," said Stanford assistant professor of physics Roger W. Romani before departing for the telescope groundbreaking that was held on Friday, March 25, at the University of Texas' McDonald Observatory, 185 miles southeast of El Paso.

UT and Pennsylvania State University are the founding partners in the project. Stanford and two German universities - the Ludwig Maximilian University in Munich and the Georg-August University in Gottingen - are junior partners.

Romani and physics professor Vahe Petrosian, who heads the astronomy program, will represent the campus at the ceremony.

Stanford has a small but extremely energetic astronomy program. Its eight active faculty members come from the physics, applied physics and electrical engineering departments and are involved in a variety of research projects totaling $5 million annually. The program supports up to 30 graduate students and has a small student observatory that is used to teach about 300 undergraduates annually.

Possession of a piece of the William P. Hobby-Robert E. Eberly Telescope therefore represents a major new asset for the program. When completed in 1996, the instrument will become one of the world's largest and most powerful optical telescopes. It also is relatively inexpensive, costing an estimated $13.5 million, compared to $100 million for the comparably sized Keck Telescope constructed recently in Hawaii.

The bargain-basement price is due in large part to the fact that the telescope has been designed for a special purpose: making spectroscopic observations of stars, galaxies and other celestial objects. It will not be as good as the Keck Telescope at making regular images of such objects, but it should be unrivaled in its ability to record their optical spectra - the variations in intensity of the light they emit over a range of different colors or wavelengths.

Spectral analysis provides large amounts of information that scientists can use in searching for planets in orbit around other stars, measuring the surface activity of stars, determining the distance of galaxies, learning more about the invisible dark matter that is thought to surround many galaxies, and refining theories about star formation and evolution.

Because of its special purpose, experts at Pennsylvania State University were able to use innovative design features to keep costs down. For example, considerable savings were realized by keeping the telescope's 33-foot primary mirror stationary rather than making it rigid enough to move without flexing. It is the first optical telescope that will use a system of smaller mirrors as a movable "tracker" to point the telescope, instead of moving the entire instrument, including the primary mirror.

"It's a lot of Big Bang for the buck," Romani said.

Once the new telescope is up and running, the astrophysicist has several specific research projects in mind.

One is an attempt to "weigh" exotic objects called neutron stars and black holes. These are the collapsed cores of exploded stars and are made up of material weighing millions of tons per ounce that is produced when atoms are squeezed so hard that their nuclei fuse together. By measuring the position and velocity of companion objects and disks of gas and dust circling such objects, Romani hopes to calculate their mass. Among other things, this could help answer the long-standing question of the existence of black holes - collapsed objects surrounded by such strong gravitational fields that not even light can escape.

Another program that Romani plans to carry out in collaboration with Petrosian involves the study of what are called gravitational lenses. Massive celestial objects, such as galaxies, cause space in their vicinity to curve. So light from more distant objects that passes nearby is bent, much like light passing through a glass lens. The new telescope's spectroscopic ability should allow the scientists to obtain estimates of the distance of extremely faint galaxies that exhibit lens effects, enabling them to make improved measurements of their mass.

In yet another collaboration, Romani will be working with associate professor of physics Peter Michelson who studies celestial sources of X- rays and Gamma rays. The scientists will use the spectroscopic telescope to provide additional information on these objects, which are among the most dynamic in the heavens.

When the Hobby-Eberly Telescope starts to operate in 1997, two Stanford scientists also will be spending much of their time in Texas. The Physics Department has approved two new positions for scientists whose research will involve using the telescope. "It's proving to be a great recruitment tool," Romani said.

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