As a first-year history major, Catherine Zucker (Col ’15) took an introductory astronomy course for non-majors. And she’s come light years since then.
In January, Zucker presented her research on the structure of the Milky Way galaxy at the American Astronomical Society conference, the nation’s largest conference for astronomers.
Professor Kelsey Johnson, who taught that introductory class, suggested a summer research position for Zucker. “It was a coincidence that I took that class and that [Johnson] thought I would be a good astronomer,” says Zucker, now a double major in history and astrophysics.
She says she got hooked on studying the universe after asking so many questions in that first class. Throughout middle and high school, Zucker explains, everything you learn has a set answer. But when she began studying astronomy, Zucker would ask questions that didn’t have known answers. “People didn’t know the answers because they haven’t figured it out yet,” she says. As a budding astronomy researcher, Zucker relishes the thought of uncovering answers. “You’re pushing the boundaries of knowledge and you’re working on things that no one has ever worked on before,” she says.
Zucker’s latest research is the discovery of “galactic bones”— dense, infrared, dark clouds that are a new class of astronomical objects, she explains. “They’re really long, skinny filaments,” she says. “We think that they define the centers of the spiral arms of our galaxy.” Identifying galactic bones will help scientists create a more accurate picture of the Milky Way, which has been difficult to study due to both the galaxy’s disc-like shape and Earth’s vantage point from within that disc.
The first galactic bone, dubbed Nessie because of its resemblance to the shape of the Loch Ness Monster, was discovered in 2013 by Harvard University astronomy professor Alyssa Goodman. Last summer, Goodman served as an adviser to Zucker as she interned at the Harvard–Smithsonian Center for Astrophysics.
There, Zucker experienced the creativity and thrill of discovery involved in bone hunting. She combed through extensive survey images from NASA’s Spitzer Space Telescope that revealed long, dense, skinny clouds that appear dark when contrasted with the bright light shining from the center of our galaxy. Zucker’s research yielded 10 potential galactic bones that were more difficult to find than Nessie, given Earth’s vantage point. She says her research focused on proving that the first bone wasn’t just a fluke, but rather one of many galactic bones to be found within the Milky Way’s spiral arms.
“We had no idea what other bones would look like—it’s hard to classify a group of objects when you only have one of those objects,” she says. Zucker helped shape the criteria to determine what qualifies as a galactic bone: for example, a filament must be at least 50 times as long as it is wide and have a velocity that matches a spiral arm. “I had a lot of freedom to figure out what should be defined as a bone and what shouldn’t,” says Zucker.
Zucker and her professors think that in theory there should be thousands of discoverable bones. “My research confirmed that this was not just a random occurrence, but that there’s a new class of objects that we can use to map our galaxy,” she says.
After graduation, Zucker plans to return to Harvard to continue galactic bone research on her way to a Ph.D. and a career of finding answers to unknown questions. For instance, although astronomers think there are four arms in the Milky Way, Zucker says, “We’re not exactly sure how many spiral arms our galaxy has—it’s an open question.”