Paula R. T. Coelho
Research
I study how galaxies evolve by reading the light of their stars. We cannot visit distant galaxies, and we cannot resolve their individual stars—all we receive is their combined light. Yet that light carries a fossil record: the imprint of the stellar births and chemical enrichment. Much like an archaeologist who reconstructs past civilizations from fragments, we use the fossil light of living stars to reconstruct the history of galaxies.
This is, at its core, an inverse problem. From the integrated signal, we develop and validate methods to infer the underlying distribution of stellar properties like ages and chemical compositions. It requires building synthetic data of stars and stellar populations, confronting them with observations, and being honest about what we can and cannot confidently know.
Stellar Spectral Libraries
What we see in galaxies is mostly the light of stars—many stars, with different properties. So we need large collections of stars with well characterised properties: Stellar Spectral Libraries.
Stellar Population Models
The mixtures of stars are not random, they obey the laws of stellar and chemical evolution. We combine individual stars into meaningful integrated light via Stellar Population Modelling.
Stellar Clusters
Stellar Clusters are the simpler—though not simple—cases of stellar populations. Since all stars form in clusters, one can think of galaxies as a mixture of stellar clusters.
Extragalactic Archaeology
We compare our simulated data with observed real clusters and galaxies. Like archaeologists, we use fossil records—the light of living stars—to reconstruct the past.
The four pillars are not independent lines of work, they are a single research programme seen from different angles. Building the foundational ingredients, understanding and questioning what they allow us to infer, validating them against real systems where both the matches and the mismatches are informative. Some of this work has found unexpected applications beyond my field, a reminder that careful foundations travel further than their original intentions.
Pleiad
Our group's name comes from PopuLações Estelares IntegrADas, which means Integrated Stellar Populations. We use the light of stars to understand the evolution of galaxies. We work across the four pillars above: from building the theoretical ingredients—stellar spectral libraries and population models—to applying them to real observations of stellar clusters and galaxies. We bridge theory and observation, connecting the physics of individual stars to the integrated light of distant systems.
Teaching
I have been teaching at the graduate and undergraduate levels in Physics and Astronomy since 2010. Most of my courses are at the University of São Paulo; in 2024, I gave guest lectures at the University of Lancaster, UK, on galaxy archaeology and stellar population models.
My classroom is not primarily a lecture hall. I cap expository time to make space for what I think matters more: discussion of texts, hands-on work in the computing lab, journal clubs, and student-led seminars. This mix accommodates different learning styles and connects theory to practice. Student evaluations confirm the approach, with consistently high ratings in didactics and encouragement of critical thinking.
I am also thinking seriously about the role of generative AI in education. Students already use these tools—often to bypass learning rather than deepen it. Rather than policing that, I am exploring how to bring AI intentionally into the classroom as a thinking partner: teaching students to engage mindfully, develop collaborative fluency with this technology, and strengthen rather than shortcut their understanding.
Mentoring
Over the years I have mentored more than twenty students—undergraduates, graduates, and post-docs. My approach gives abundant autonomy, fosters international networking and collaboration, and supports students as whole human beings navigating a competitive field. Research is hard enough without having to do it alone.