'U' researchers bring dark matter, spectra and dwarf galaxies to light

The construction of the Detroit Observatory in 1854 ushered in a new era for the University. Its reputation as a research institution began to develop then, and has expanded exponentially ever since. And the astronomy department, which has played an intricate role throughout this history, continues to do so today. Discoveries are being made about our universe at sites in Ann Arbor and at facilities worldwide.

Research has improved in part thanks to modern instruments, such as one designed by University assistant astronomy Prof. Gary Bernstein. Two years ago he completed a useful creation: His Big Throughput Camera collects light faster than any other astronomical instrument in existence.

Courtesy of Gary Bernstein A photograph taken by the Big Throughput Camera, built by a University professor.

"The currency of our trade is light," he said. "The more we can collect, the more we can do."

The BTC is being used for many projects. Bernstein uses it to study how bending light in the universe distorts what we see. Much is hidden to our eyes, he said.

"We believe 90 percent of the matter in the universe takes some invisible form ... it's called the dark matter," he said. To learn about this, he is "taking pictures of millions of galaxies and looking for very subtle distortions."

Our galaxy has about 10 billion stars, and about 100 billion galaxies can be seen. Each picture he takes "has tens of thousands of galaxies in it," he said. "If we had to do them one at a time, we'd never get there."

Chris Smith, a postdoctoral fellow in the department of astronomy, is in Chile using the camera now. He is studying two nearby galaxies, known as the Large and Small Magellanic Clouds. These galaxies are close enough to us to allow for the study of detail, he wrote in an e-mail, but they are "far enough away that we can see the 'big picture,' the whole galaxy."

In his research, he has discovered several supernova remnants. He described these as "remnants of stars that have exploded, leaving bubbles of gas and driving a shock wave, or sonic boom, into the surrounding interstellar gas."

Bernstein's camera was installed at a government-owned observatory in Chile two years ago. It will be in use for at least several years, and may be moved to the Magellan telescope when that is finished.

The Magellan telescope, the first part of which will be completed around the year 2000, will be the largest private astronomy facility in the southern hemisphere. The $67.7 million project, a collaboration of five universities in which the University of Michigan has a 10 percent share, will have a huge impact on research, Bernstein said.

Other University research projects include the Michigan Spectral Catalogue (HD Project), which aims to reclassify all of the Henry Draper stars using the Morgan/Keenan system. The Henry Draper Stars were originally classified before 1920, and the system is ready to be updated. Led by Nancy Houk, a University research scientist, this reclassification will stretch from the South Pole to the North Pole. The results will be published in seven volumes, the fifth volume of which is in progress.

"Because we now have better spectra (small images) of the stars, you will be able to tell a lot about the stars; if it is a dwarf or a giant," Houk said. This research, she said, will have broad applications in astronomical research worldwide.

There are a number of other projects in the works as well. Among them are the projects of associate Prof. Mario Mateo and Rackham student Kristen Chiboucas, who are striving to better understand the construction, formation and evolution of galaxies.

Mateo is studying dwarf galaxies, the most common type of galaxy in the universe. Made up of faint, old stars, dwarf galaxies are very hard to see.

"It's tricky," Mateo said of studying them. "They're very puny galaxies ... They are just fascinating little things."

Mateo is finding that the simple systems can have complex histories, and he has found a dwarf galaxy that seems to have formed stars three or four times in its lifetime, a rare phenomenon. Some dwarf galaxies are forming stars right now, helping astronomers gain a better understanding of the origin of galaxies. However, there is still much to be learned, such as why stars are forming in the first place.

"There's so much we don't know," explained Mateo. "There is no rhyme nor reason to what they are doing."

The galaxies are revealing evidence of dark matter, said Mateo, who said understanding dark matter keeps scientists busy.

"It's a problem that's really resisting everybody's efforts," he said and hoped researchers would learn more about it soon. "I hope I'm around still when that happens."

He's also studying the relationship between dwarf galaxies and larger ones. To do this, he looks at the distribution of stars in our galaxy for evidence of broken-up old galaxies. He is taking a different approach than other astronomers, by looking at closer galaxies, which he refers to as "local areas of the universe."

"You can reconstruct the past by looking locally," he said. He explained that looking far away is like looking into the past because light has taken a while to reach us.

Mateo said astronomers have learned much in the past decade. Ten years ago, astronomers didn't know that galaxies could be so different. "It's really been exciting in the last few years," he said.

These research projects are just a taste of that going on. Resources, as well as new and improved technology, play a role in this surge of astronomy research.

Michigan's involvement with such major research projects as the Magellan will, said astronomy Prof. Douglass O. Richstone, "allow the University to play a leading role in the golden age of cosmic exploration now in its infancy."

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