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Searching the Skies: Students Observe Pulsars at the Arecibo Observatory

by Sue Kropp

Stinebring taking a break from the observatory at the beach.


Lead Image: Searching the Skies
left to right: Aaron Webber '03, Henry Barnor '04, Daniel Berwick '05, Alex Hill '04, with the telescope's receiver in the background.

JULY 10 , 2002--"The hundreds of billions of stars that make up the Milky Way and the interstellar medium--the gas molecules and dust particles that exist between the stars--are constantly rotating around the center of the galaxy, much like the planets rotate around the sun," says Associate Professor of Physics Dan Stinebring. "There are also pockets of turbulent gases within the interstellar medium that create small, swirling motions within the medium. Studying this more detailed motion of interstellar gases can help us understand how our galaxy works."

Earlier this summer, Henry Barnor '04, Alex Hill '04, Aaron Webber '03, and Daniel Berwick '05 accompanied Stinebring to the National Astronomy and Ionosphere Center in Arecibo, Puerto Rico, to explore this turbulence further. The team spent two weeks recording and studying data gathered from pulsars--highly magnetized neutron stars that spin quickly, emitting radio waves--with support from the National Science Foundation.

"Working at Arecibo was exciting as an undergraduate," Webber says. "It was definitely a good experience to meet other scientists and see the different projects that they were working on."

For four hours most afternoons and from 12:30 a.m. to 4:00 a.m. every night for two weeks (observing time is allocated on a competitive basis to researchers around the world), Stinebring and his students had their chance to use Arecibo's mammoth radio telescope. The students would point the telescope toward the pulsar they wanted to study, calibrate the device, and run a computer program to collect data at different frequencies over a specific period of time.

"I kind of expected the operating technicians at Arecibo to set the telescope's coordinates for us," says Berwick. "Instead, we got to do this as part of our research. After we punched a few keystrokes into the computer, the telescope would move and point toward the part of the sky we wanted to observe. It was amazing."

After the observatory's computers collected the necessary data, Stinebring's student research team ran another program, which they wrote themselves, to process the information and create three-dimensional graphs of the spectra that had been observed by the telescope.

"The radio waves that we collected are scattered in space by electrons in the interstellar medium," Berwick says. "By looking at the distortion that this scattering creates, we can learn more about pulsars, and explore the composition of the medium, too."

A view overlooking the 305-meter diameter Arecibo radio telescope. The spherical radome, which is suspended 130 meters above the surface, houses two additional reflectors and the radio receivers. The 900 tons of steel and advanced electronics are held up by the three 120-meter tall concrete support towers.

Stinebring and his students are spending the rest of the summer analyzing the data they've collected and constructing a model to explain why and how the radio waves from pulsars are scattered before they reach the Earth.

"We set out this summer to test the ideas we had gathered about this phenomenon from previous research," says Stinebring. "So far, our preliminary analysis is supporting our predictions, which is every exciting."




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