BOWLING GREEN STATE UNIVERSITY


Students Andy Broderick (left) and Steve Dembkowski (right) work with Dr. Andrew Layden (center) studying pulsating stars.

Students Andy Broderick (left) and Steve Dembkowski (right) work with Dr. Andrew Layden (center) studying pulsating stars.

Stargazing students at BGSU seek answer to decades-old question

Some of Dr. Andrew Layden’s students have spent their summers staring at the stars.

But it’s not just any stars they’ve been watching since 1999. The stargazers have trained their BGSU telescope on a particular class of the celestial bodies in an effort to resolve a 50-year dispute.

Layden, physics and astronomy, has enlisted nearly 20 undergraduate and graduate students—many for more than one year—to study pulsating RR Lyrae stars. “We’re looking at these things as part of a project to figure out what their true wattage is,” he explains. “Our goal is to end, once and for all, the arguments about what their luminosity is.”

That figure is currently estimated at 30-50 times the luminosity of the sun, according to Layden, and to narrow it down, he adds, researchers must also determine how far away the stars are.

Known to exist for roughly 100 years, RR Lyrae stars pulsate “very strongly and very regularly,” causing their size to vary by 15-20 percent twice a day, he says. As they get larger and smaller, they get brighter and fainter as well. At the same time, gas on the stars’ surface changes temperature, causing changes in color—they’re blue, or hotter, at their brightest and red, or cooler, when dimmest, he notes.

The BGSU students take pictures of the stars with a telescope-mounted camera, then measure their luminosity on the pictures and chart the changes over time on a graph. This summer, those students have been nighttime observers Steve Dembkowski, a sophomore from Strongsville with a minor in physics, and Ryan Lorek, a physics major from Fostoria who graduated in May, along with Andy Broderick, who has done daytime computer work as well as observation. A senior physics major from Newark, Broderick will be working with Layden again this fall on an independent study research project.

Finding the stars’ distance from Earth is the other part of the equation. They’re scattered around the galaxy, from 3,000-7,000 light years away, Layden points out, saying that estimates have varied by about 10 percent over the last 50 years or so. He is part of a 20-year project with NASA to build a Space Interferometry Mission (SIM) satellite that would be able to accurately measure distances to celestial objects. Original plans called for a 2009 launch, but the project—involving more than 100 scientists working on roughly a dozen distance-measuring studies—is now on hold indefinitely, he says, mentioning 2015 as a possible alternative date.

Layden’s hopeful, however, that an eventual combination of the SIM satellite and measurements of the stars’ brightness by telescope will enable an accurate determination of the disputed wattage.

Two of his former students, Jeff Gregorsok and Goldwater Scholar Katie Guldenschuh, presented a paper about the Variable Star Project at the American Astronomical Society’s national conference in 2004. And Broderick says his work with Layden has taught him a lot not only about variable stars and scientific observation but also about “how to read and what to look for in a scientific paper. Probably most importantly,” he adds, “I’ve learned how science is really done, by real scientists, in the read world.”

In 2006, Layden’s efforts with students were rewarded with BGSU’s Elliott L. Blinn Award for Faculty-Undergraduate Basic Research/Creative Work, which included $4,000 for continued support of undergraduate research. That money “kept summer students going,” as well as some independent study projects, says Layden, who may apply this fall for a National Science Foundation grant for a different vein of the same study.

“For the foreseeable future,” he predicts, “I still see us using the telescope to look at variable stars.”

August 6, 2007