Stellar Detective: A profile of professor Mercedes Richards

Printed on the pages of Mercedes Richards' high school yearbook, a friend's parting sentiment reads: "Mad Mercy! Her ambition is to obtain a Ph.D. in Astronomy!" Like only a few of her classmates back in Kingston, Jamaica, Richards, now professor of astronomy and astrophysics at Penn State, loved looking up at the skies. "I made a decision 'round about 6th grade or so that I wanted to be an astronomer," she declares.

Having set her sights on the stars at such a young age, Richards has since become one. After academic stops at the University of Virginia and the Institute for Advanced Study in Princeton, she joined the Penn State faculty in 2001. In 2008, in recognition of her record of international accomplishment, she was awarded Jamaica's highest academic honor, the Musgrave Gold Medal. "Mad Mercy" has come a long way, but it hasn't always been easy. "The road I have traveled has not been smooth," she says. "There have been some obstacles."

A Star is Born

"The stars in Jamaica are really, really beautiful," Richards remembers. "My father and I would just sit outside and talk about life and philosophy under the canopy of the skies. More than anything else I wanted to understand what was going on. Why do stars shine?"

Richards credits her father—a police detective—for bestowing on her the skills of observation and deduction, and she is grateful to her mother—an accountant—for instilling in her the importance of precision in her work. While raising her in a suburb of Kingston, her father often took her to a nearby botanical garden shortly after dawn. In the early morning quiet, father and daughter sat in awe of the nature around them ("It was like being in a place of worship"), and her father taught her to identify the nuanced varieties of plant species.

Today, Richards uses that same set of skills to examine the stars. "What I do is definitely detective work," she explains. "Astronomers want to know what happened. We look for evidence. We have to piece it all together like forensic scientists of the sky."

Richards' research specialty is binary stars, systems of two stars orbiting around a common center. Binaries are important to astronomers because their orbital patterns, determined by the gravity that binds them, provide a direct method for calculating a star's mass. But binary stars are more than cosmic dance partners; they often behave somewhat like sibling rivals, interacting in ways that can lead to cataclysmic tantrums. "Most of the exciting things that happen in the sky occur in binaries," says Richards.


NASA

Neutron star EXO 0748-676 (blue sphere) is part of a binary star system, and its neighboring star (yellow-red sphere) supplies the fuel for the thermonuclear bursts.

If a young star like our Sun, for instance, pairs with a white dwarf—a small, super-dense star that has burned most of its fuel—the white dwarf's superior gravity strips gaseous matter from the surface of its partner, she explains. "The gas flows around the white dwarf and piles up like a traffic jam." Called an accretion disk, this growing pile-up becomes increasingly pressurized, eventually triggering a thermonuclear reaction. These fantastic explosions known as novae and supernovae can emit more energy than our Sun will generate throughout its entire life span.

Finding Flow

Because vast distance prevents astronomers from actually seeing the build-ups to these calamities, they use a process called spectral analysis to learn what's happening. As a prism separates sunlight into its rainbow of component parts, or spectra, a spectrometer splits the accretion disk's electromagnetic radiation into characteristic patterns. Richards studies these patterns like fingerprints, determining a star's elemental composition and its motion relative to Earth. It's a task, she says, that reminds her of her childhood, and being dazzled by the colors cast by crystal chandeliers.

To test the gas-flow model she created for her doctoral thesis, Richards borrowed a technique from the medical field. "Astro-tomography is very much like taking a CAT scan of the stars," she explains. "We get many spectral observations from all around our patient—the binary system—as it moves in relation to the Earth. Then we add all those observations together. The resulting composite image shows us how the gas moves between the stars." Using this method, she not only confirmed her model's accuracy, but also showed that the force of gravity operates between binary stars just as predicted by the laws of physics. While compiling tomographs of several binary pairs she saw "a beautiful image of gas flowing along the predicted path," she remembers.

Richards has continued to model gas flows between binaries to the present day, currently in collaboration with a team of Russian scientists. ("It's interesting because we communicate by email and we've never actually met in person," she says.) Her dream is to one day create a full-blown three-dimensional model of these flows. "It's going to take a while," she laughs. "But I'm like a dog with a bone. I'm not letting go."

Planetary Politics

While planets aren't her specialty, Richards was involved in one of the more high-profile astronomical decisions of recent years as a voting member at the 2006 meeting of the International Astronomical Union (IAU) in Prague. There, to the dismay of schoolchildren and skywatchers around the world, Pluto was stripped of its status as a full-fledged planet.

Given recent discoveries of more and more planet-like objects at the edge of our solar system and beyond, she says, "It was obvious that Pluto didn't belong with the larger planets." Though she acknowledges that behind-the-scenes politics made the decision controversial, in the end she cast her vote to change the definition of a planet and re-categorize Pluto as a dwarf.

Last fall, when she received the email explaining that she had won the Musgrave Gold Medal, Richards at first thought it was a joke. Vaguely recognizing the email's author, she telephoned her mother in Jamaica before deleting it, and found that indeed the Institute of Jamaica had chosen to recognize her with its most prestigious honor, reserved for Jamaicans who have made "a significant international impact" through academic accomplishment. Only 14 other scientists have received the gold medal in the award's 111-year history.

In her acceptance speech in Kingston, Richards urged the government of Jamaica to have a higher regard for science. "In Jamaica the cultural stuff—Bob Marley, dance, history—is perceived to be closer to people's lives than science," she explains. "Science is thought of as something that weird people do. I'm hoping kids will learn to see that science is something natural and positive."

"I disagree when people say that what astronomers do is useless," she adds. "Astronomy has an influence on every aspect of our lives. The time on your watch is set by astronomers," she says, tapping her wrist.

Debts Repaid

The high school that Richards attended in Kingston, St. Hugh's, was segregated by gender; her classmates, as well as her teachers, were all female. "Having those female teachers gave me a boost," she recalls. "As a young woman I could say, "Hey, I can be like them." Thus inspired, she was able to soldier on through graduate school at the University of Toronto at a time when she says an all-male faculty tended to be tough on female students. The early encouragement also helped in her first academic position in a department where she was the only female faculty member.

Today, as a tenured full professor at Penn State, Richards loves inspiring her students ("infecting" them, as she puts it) with a passion for science. "I think I would lose something very important if I were locked away just doing research and not teaching," she says. Named a Harlow Shapley Visiting Lecturer in astronomy by the American Astronomical Society in 2004, she visits college campuses throughout the United States, Canada, and Mexico.

Back home, she teaches Astro 001, an introductory course in which hundreds of non-science majors enroll each semester. "I feel I'm on a mission," she says. "It's very important for us to pass on an understanding and an appreciation of science because these students are going to be running the government and our universities. I want them to say ten years from now, "Wow, I enjoyed that class. Science is fun."

Her busy academic schedule allows her little free time. Even leisure reading—detective novels are among her favorites—is a luxury, she says. "I don't really have enough time for friends," she admits. But for "Mad Mercy" Richards, "That's part of the price you pay if you want to be successful in any field."

"I love the feeling that I have when I discover something new," she says. "And I try to pass on the excitement of astronomy to as many people as possible."

Mercedes Richards, Ph.D., is professor of astronomy and astrophysics in the Eberly College of Science, mrichards@astro.psu.edu.

Last Updated August 05, 2009