młody mężczyzna , w tle gwiazdy — Dr Piotr Antoni Kołaczek-Szymański in Białków Observatory, photo: private archive and an astrophotography from European Southern Observatory’s webpage (ESO/José Francisco, josefrancisco.org).

Dr Piotr Antoni Kołaczek-Szymański receives the Prime Minister’s Award

Two researchers from the University of Wrocław were awarded this year’s Prime Minister’s Award in the category for an outstanding doctoral dissertation: dr Piotr Antoni Kołaczek-Szymański from the Institute of Astronomy, and dr Rafał Muda from the Institute of Psychology.

Dr Piotr Antoni Kołaczek-Szymański discusses his doctoral thesis titled “Ekscentryczne zmienne elipsoidalne oraz ich oscylacje wzbudzane pływowo i o początkach” (eng. The Eccentric Ellipsoidal Variables and Their Tidally Excited Oscillations)and reflects on the beginnings of his fascination with astronomy.

Dr Kołaczek-Szymański remarks on his award: “I am honored to have received the Prime Minister’s Award, as I am certain that my doctoral dissertation had to compete with many highly interesting theses. I view this award as a recognition of astronomical research among other empirical sciences. From my perspective, as I grow older, I increasingly notice that astronomy and astrophysics are truly unique compared to other sciences, as they blend strict mathematical theories with profound philosophical questions about the nature of the universe, its meaning, and our place within it. These questions fuel not only academic discussions but also, often without our awareness, our perception of life depends on how we answer them. The opportunity to be in the presence of and collaborate with those who strive to solve the endless mysteries of the cosmos is a great privilege.”

The astronomer evocatively discusses the results of his doctoral thesis: “As Earthlings, we have direct access to only one star, the Sun. However, one glance at the clear night sky (but maybe not from the Market Square in Wrocław during the full moon) will make it apparent that our “daystar” is only one of many stars existing in the “vacuum” of the Universe. We estimate that in the Milky Way alone, there are over one hundred billion stars, which is even more impressive if you were to write down all those zeros: 100 000 000 000! Then, if you were to think about all the other hundreds of billions of galaxies, you could get a migraine, since the numbers become truly astronomical.”

Eccentric binary black holes and stellar evolution

Dr Kołaczek-Szymański states: “ Even though we might suspect that there is a similar amount of argument for and against the Sun being in some way exceptional, it can be said without a doubt that its life and death will be rather uneventful (although that cannot be said for its third planet). This is not the case for the so-called massive stars, i.e., stars with a mass approximately eight times greater than that of the Sun. Their evolution is associated with intense stellar winds driven by strong radiation pressure, and they meet their end in a spectacular supernova explosion, which John Craig Wheeler once described as a true cosmic catastrophe. There is at least one more difference between massive stars and their less massive siblings, such as our Sun. The former almost always have star companions, which are almost exclusively massive stars as well. We refer to this as a binary system, and the evolution of the components in such systems is much more complex than the evolution of a single star, such as the Sun. The issues of star binarity and their fundamental impact on our understanding of the structure and evolution of those “cosmic reactors” have significantly influenced modern astrophysics, thanks to, for instance, the growing field of gravitational-wave astronomy and the techniques developed for their detection. It is the binary systems with massive stars that leave behind eccentric binary black holes and binary neutron stars, which, through merging, create the sources of gravitational waves that penetrate the Earth. Therefore, to study these systems containing the remnants of stellar evolution, one must know everything there is to know about the life and interactions between the stars in a binary system. This was precisely the context for my doctoral dissertation.”

Heartbeat stars

Massive binary systems are often characterized by highly elliptical orbits, which vastly differ from the circular ones. What that means is that the stars in such a system periodically come closer and further away from each other. Once they reach periastron of their orbit (the moment in their movement on the orbit when they are the closest to one another), both of the stars are deformed as a result of tidal forces (the same ones that take place between the Earth and the Moon). When combined with the mutual increase in brightness and Doppler beaming, a characteristic light “pulsation” appears, which can be recorded on Earth from hundreds or thousands of parsecs. Precisely because of the unusual shape of the light curves of those binary systems, they are sometimes called heartbeat stars, or, more accurately, eccentric ellipsoidal variables.

Binary star systems are like children on a swing

Dr Kołaczek-Szymański explains: “As a result of periodically changing tidal forces, another interesting phenomenon occurs: tidally excited oscillations. Even though the name seems to suggest an awfully complicated process, it could be explained with a simple everyday analogy. Each day, playgrounds in Wrocław are filled with children. Some of them enjoy playing on swings; one of the kids will help their playmate by pushing the swing. The problem is that pushing the swing is rather exhausting and takes a lot of work. Every swing enthusiast knows that playing on a swing does not last forever due to what a physicist would call resistive forces. Sooner or later, the person making the swing move will be tired enough to stop pushing the swing to the great dissatisfaction of the kid on the swing. Stars in a binary system are analogous to this situation. Just like the child pushing the swing, one of the stars can throw another off-balance with its tidal interactions and force it to periodically pulsate. However, those pulses have a cost; just like pushing a swing, they require physical effort, and only the gravitational potential energy and the total angular momentum can “spin” the binary system. The stars convert that momentum into kinetic and thermal energy connected with tidally excited oscillations. As a result, the orbit becomes more circular and shortens; the stars can now rapidly approach each other. Here we circle back to the problem with the “desertion” of the person making the swing move. What is the stellar equivalent of getting tired? Turns out that a binary system can use so much of its potential energy and angular momentum that both stars get dangerously close, and they can no longer continue their stable trajectory on the orbit around a common center of mass. What happens then is one of the most fascinating phenomena in the Universe: two stars become one, which has new special properties. Therefore, tidally excited oscillations are a unique type of stellar pulsation, because they shape the evolution of binary systems, and sometimes they can affect the fate of those systems. Searching for their observational examples and later analyzing them is essential to improve our models of tidal interaction in binary and multiple star systems.

Thanks to the realization of his doctoral project, over one thousand new heartbeat binary systems have been discovered in the Milky Way and the Magellanic Clouds, the latter being the satellite galaxies of the former. An absolute novelty is also the discovery of over 150 modes of tidally excited oscillations in the previously mentioned systems. Those observations, alongside the effects of theoretical simulations, largely contribute to the expansion of knowledge about tidal interaction in eccentric binary systems.

Astronomy lessons before learning how to read and write

Dr Piotr Antoni Kołaczek-Szymański’s fascination with astronomy started at the age of four. He reminisces: “I would sneak to my parents’ bookcase to get the thick tome of Astronomia Ogólna by prof. Eugeniusz Rybka (a famous Polish astronomer, who for some time was the director of the astronomical observatory at the University of Wrocław). My dad kept this book after taking an astronavigation course years prior. Even though I did not know how to read or write, the pictures stimulated my imagination and captivated me with their mystery and promise to discuss profound topics. Many times, I would almost obsessively copy one of the pictures, the figure of the Solar System, using crayons. Those were my first astronomy lessons.”

He adds: “After being enchanted with the beauty of sciences, during the last year of middle school, I decided to become an astronomer, which became even clearer once I participated in the National Astronomy Olympiad multiple times in high school. In the meantime, I was partaking in astrophotography, which taught me a lot about observational astrophysics. Studying astronomy was inevitable in my case, and the Institute of Astronomy of the University of Wrocław was chosen for many reasons.” Dr Kołaczek-Szymański wrote his bachelor’s and master’s dissertations on observational astrophysics of stars. During his graduate studies, he had the opportunity to work under prof. Andrzej Pigulski (from the Institute of Astronomy of the University of Wrocław) as a scholar for a project funded by NCN titled “Asteroseismology of hot stars in the era of space observations and massive photometry.” He states: “It was the perfect opportunity for me to learn about the analysis of photometric data from satellites and Fourier analysis of time series. After graduating, I decided to continue learning more about my interests, and I enrolled in the Doctoral School at the University of Wrocław under the guidance of prof. Andrzej Pigulski. I started applying for observation time at leading astronomical observatories and working with astrophysicists from Białków Observatory at the University of Wrocław. Thanks to my collaboration with astrophysicists from Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences in Warsaw, I had the opportunity to carry out astronomical observations for the Araucaria Project in the Polish astronomical observatory Cerro Armazones in Chile.” On top of gaining scientific experience, his PhD studies at the University of Wrocław allowed him to gain didactic experiences as well, as he led many practical and laboratory classes for participants of astronomy and math courses. As part of his doctoral project, he was the principal investigator for his first NCN PRELUDIUM grant, titled “Observational analysis and theoretical modeling of tidal effects in eccentric binary systems containing massive components.” He explains: “Especially that last part helped me to grow as a researcher, since I was fully responsible for the realization of research purposes, time management, and thanks to the granted resources, I could participate in and present my findings at many international conferences and workshops.”

Nowadays, he is an assistant professor at the Institute of Astronomy of the University of Wrocław, and as part of his post-doctoral internship, he is continuing his research with experts on massive binary star systems and their emission of X-rays from the Université de Liège in Belgium. At the same time, he is actively working with astrophysicists from Wrocław as part of the NCN OPUS grant, called “Binarity as a clue for understanding the origin of blue large-amplitude pulsators (BLAPs).” He is also a member of the Polish Astronomical Society.

The articles that contributed to dr Piotr Antoni Kołaczek-Szymański’s doctoral dissertation were published in prestigious international journals such as Astronomy&Astrophysics, The Astrophysical Journal, or The Astrophysical Journal Supplement Series and can be found online under those titles:

About the award

Each year, as a recognition of scientific achievements, the Polish Prime Minister grants the Prime Minister’s Award in three categories:

for an outstanding doctoral dissertation
for highly advanced scientific research that fulfills a postdoctoral degree
for significant scientific achievements, including artistic creation, or implementation activities

The Prime Minister can grant no more than 45 awards each year, including 25 for doctoral dissertations, 10 for significant achievements qualifying for a postdoctoral degree, and another 10 for the last category. This year, 43 individuals were awarded.

Written by: dr. Piotr Antoni Kołaczek-Szymański

Date of Publication: 25.11.2024
Added by: E.K.

Translated by Marta Kawik (student of English Studies at the University of Wrocław) as part of the translation practice.