Are we alone? This is the question that drives Ekrem Esmer, a McDonnell Center Postdoctoral Fellow at WashU, in his search for exoplanets. While most studies focus on single star systems, Esmer investigates the less-explored realm of multistellar systems, which are abundant throughout the galaxy. His research aims to determine whether planets similar to the fictional Tatooine from Star Wars can form and thrive in multistellar environments, and if such planets could potentially support life.

Planets orbiting binary stars are rarely detected, with only about one being found for every 100 planets discovered around single stars. This scarcity may stem from a variety of factors. Challenges in planet formation could arise due to the complex gravitational interactions between multiple stars, which may hinder the formation of planets. Orbital dynamics in multistellar systems are also more intricate, leading to unstable planetary orbits where planets might struggle to maintain their positions or could be ejected from the system altogether. Additionally, observational bias plays a role; detecting planets in multistellar systems is inherently more difficult due to the added complexity in distinguishing planetary signals from the multiple stellar components that could mask or mimic planetary signatures.

Esmer's work involves measuring the frequency of circumbinary planets in the galaxy, using data primarily from NASA's Transiting Exoplanet Survey Satellite (TESS). He is a member of AstroMusers and collaborates closely with Tansu Daylan, an assistant professor of physics and fellow of the McDonnell Center for the Space Sciences at WashU, known for his expertise in exoplanets and TESS data. 

Esmer employs a technique for detecting variations in eclipse timings of binary star systems, similar to the method used in the first exoplanet discovery in 1992. Using this approach, he discovered two planets orbiting the binary system Kepler-451 in 2022. He also conducts simulations of binary systems with planets to estimate detection rates. In these simulations, he generates synthetic binary star systems, adds planets to them, distributes them across a simulated sky, and models their observations as if performed by TESS. He then applies the same detection technique to these simulated observations to evaluate the efficiency of planet discovery.

Looking ahead, Esmer plans to apply different detection techniques to enhance the overall sensitivity to circumbinary planets. By combining various methods, he aims to provide a more accurate estimate of the abundance of these planets in the galaxy.

Esmer earned his undergraduate and graduate degrees from Ankara University in Turkey, where he first collaborated with Daylan during his graduate years, forming a professional partnership that continues to thrive.

Beyond Washington University, Esmer co-leads two externally funded research projects in Turkey. These projects focus on detecting planets around evolved binaries and developing direct imaging target lists in multistellar systems.

Esmer feels that scientists have a responsibility to engage with the public, and he does this by organizing Astronomy on Tap events in St. Louis. Astronomy on Tap STL is part of a global initiative to bring astronomy to the general public. “Astronomy is naturally engaging and accessible for public outreach, so it plays an important role in connecting science and academia with the public,” he says. The program typically features monthly astronomy talks during the academic year, making complex astronomical concepts accessible to everyone.

Daylan remarked on his contributions, saying: "It's been an immense pleasure to work with and mentor Ekrem. His arrival has contributed to the rapid growth of our new planetary astrophysics research thrust at WashU. Moreover, his help in organizing Astronomy on Tap is instrumental in translating astronomical research for the public in an accessible way.”

Apart from his research, Esmer contributes to the academic community through teaching. In his previous position, he taught undergraduate-level astronomy courses, and he continues to complement that experience at WashU. In the fall of 2024, he covered a couple of lectures for Daylan's course, Physics 1210, Gateway Expeditions into Exoplanets.

He has also mentored several graduate students, supporting their development in data analysis, orbital modeling, and project design in exoplanet science.

Living in St. Louis has been a great experience for Esmer. He and his wife Işıl Esmer, an astronomer who focuses on promoting STEM education among children, live near Forest Park. Together, they frequently enjoy the cultural and recreational offerings of St. Louis, including visits to the Art Museum, Missouri History Museum, St. Louis Zoo, Gateway Arch, St. Louis Ballet, Union Station, and the St. Louis Aquarium. Esmer has the City Museum on his list of places to visit in the near future. He is especially interested in St. Louis’s historic role in early western expeditions.