Grant Donnelly ’19, a John Carroll University graduate with a major in physics and a minor in mathematics, is expanding the boundaries of physics through his Ph.D. research at the University of Toledo. Under the guidance of his current advisor, Dr. J.D. Smith, Donnelly is investigating the cosmic characteristics of interstellar dust as part of an active research fellowship and observing program. He and his colleagues recently had their research published in The Astrophysical Journal.
Advancing Research in Astrophysics
Donnelly is exploring how dust behaves and evolves in space using data from NASA and other research facilities. His work focuses on refining models of how light interacts with cosmic dust, a crucial aspect of understanding galaxy formation and the life cycle of stars.
“I study the smallest of these dust particles, which are actually much more like smoke or soot than the dust we’re used to on Earth,” Donnelly explains. “Astronomers really care about dust because it acts like a filter when we try to observe stars or galaxies behind it. The better we understand the properties of the dust, the better we can interpret what’s behind it.”
Interstellar dust—tiny particles composed mainly of carbon and silicon—plays a crucial role in how light travels through the galaxy. Donnelly’s research explores how this dust interacts with light and how it responds to intense environments, particularly those around supermassive black holes. “For some galaxies, the central black holes are swallowing matter rapidly and emitting huge amounts of radiation. That radiation can destroy—or technically, sublimate—dust. So by studying the dust, we’re actually studying how black holes affect their galaxies.”
Foundation for Scientific Success at JCU
While at John Carroll, Donnelly was mentored by Dr. Jeff Dyck, Professor of Physics, and actively engaged in undergraduate research. “When I was at JCU, we had a great group of very supportive and engaged faculty and students,” Donnelly recalls. “For a physics department of our size, we had some great equipment for hands-on experiments—I still clearly remember testing the resistance of a superconductor.”
Perhaps most influential to Donnelly was being selected to participate in the University’s Summer Undergraduate Research Fellowship (SURF) program, supported by the Colleran Weaver Fund, in 2018. Donnelly worked with Scholar-in-Residence Dr. Robert Kehoe on a project that deepened his interest in astrophysics and set the foundation for his future studies. That summer, Donnelly studied variable stars—stars that change brightness over time—and discovered three new ones, which turned out to be pairs of stars orbiting so closely they were touching. This project opened the door for his senior research on Cepheid variable stars and led to developing a method to measure how their pulsation periods change over time.
“The SURF program at JCU is probably the most significant reason I am working on a Ph.D. right now,” he said. “Getting into grad school for astrophysics is extremely competitive, and undergraduate research experience is the single most important thing you can do. SURF gave me that opportunity.”
That early experience turned out to be similar to the daily work Donnelly now performs in graduate school. “I didn’t know it at the time, but the process of research I learned through SURF mirrors what I do now. That experience helped me realize I enjoy research, and that I wanted to pursue it further.”
As Donnelly continues his research on interstellar dust, he remains deeply rooted in the lessons and values instilled at John Carroll. “JCU gave me the kind of individualized attention and support that made all the difference,” he shared. “It’s where I found my footing as a scientist.”
John Carroll’s physics program emphasizes hands-on learning and mentorship, which assisted Donnelly on the way to his success. As Donnelly continues his doctoral research, he remains a proud Blue Streak, an example of how John Carroll’s liberal arts foundation and strong STEM curriculum can launch students into cutting-edge scientific careers.