The winners of the Maria Skłodowska-Curie and Pierre Curie Polish-French Science Award are Professor Grzegorz Pietrzyński of the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences in Warsaw and Professor Pierre Kervella of the Paris Observatory (Observatoire de Paris). Pierre Kervella of the Paris Observatory, for combining complementary experiments in stellar interferometry and observations of binary stars to precisely determine the distance to the Large Magellanic Cloud and thus create a reference point for measuring distances between galaxies to better measure the expansion of the universe.

Joint Research Description

The scientific collaboration of Grzegorz Pietrzyński and Pierre Kervell has been developing within the framework of the Araucaria Project, which has continued for more than 13 years. The work has resulted in 35 publications in peer-reviewed scientific journals (including several in the prestigious Nature), cited more than 1090 times. It has also laid the groundwork for the training and development of many graduate candidates and postdoctoral researchers, who are now pursuing their scientific careers at the world?s most renowned research centers.

The winners are tackling one of the biggest problems in cosmology: the determination of absolute distances in the universe. This is an extremely ambitious undertaking, which seeks to determine not only the scale but also the physical nature of various objects. Knowledge of cosmic distances also allows for describing the rate at which the universe is expanding and may lead to revealing the nature of the ? so far enigmatic ? dark energy. The research by the winners? teams has made it possible to precisely determine the distance to the Large Magellanic Cloud (LMC).

The LMC is the satellite galaxy closest to the Milky Way, which is the most important calibrator of the cosmic distance ladder. The distance to the LMC is now the basis for almost all empirical determinations of the so-called Hubble constant, which in turn, is crucial to understanding the evolution of the universe and investigating the nature of dark energy. Until recently, one of the main challenges in determining the Hubble constant has been the unsatisfactory precision of measuring the distance to the LMC.

To solve the above problem, Professors Pietrzyński and Kervella combined several techniques used in modern astrophysics. Their methods include stellar interferometry performed by the French team, while the Polish team focuses on observations of eclipsing binary stars that orbit their centers of mass. This allowed the teams to determine the distance to the LMC with the highest accuracy ever ? that of one percent ? and to determine that the Large Magellanic Cloud lies 49.59 kiloparsecs away from Earth (about 161,000 light-years). Moreover, the methodology proposed by the winners lets scientists calibrate other methods that will allow measuring distances to very distant corners of the universe. Achieving this goal was possible thanks to the exchange of knowledge and synergistic integration of different research approaches used by the collaborating teams.

About the winners

Grzegorz Pietrzyński (born in 1971 in Nowy Dwór Mazowiecki, Poland) is a Professor of Astronomy at the Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences in Warsaw, founder and head of the international Araucaria Project, which aims to calibrate the cosmic distance ladder, and the initiator and director of the Polish Cerro Amazones Observatory in Chile.

Prof. Grzegorz Pietrzyński_fot. Magdalena Wiśniewska-Krasińska_Archiwum FNP

Prof. Grzegorz Pietrzyński_photo: Magdalena Wiśniewska-Krasińska_FNP Archives

Pietrzyński graduated from the Faculty of Physics at the University of Warsaw, where he received his Ph.D. and later his habilitation degree. He collaborated with Princeton University, the European Southern Observatory, and he worked at the Warsaw University Observatory for 20 years. He lectured at research institutions in Japan, Germany, France, Belgium, Italy, and China, among other countries. In 2014, he received the title of full professor of physical science.

His scientific output includes more than 400 publications, which have appeared in the most prestigious journals ? including Nature, Science, Astrophysical Journal, and Astronomical Journal ? which were cited more than 23,000 times.

Pietrzyński is the recipient of many prestigious Polish and foreign research grants, including two prestigious grants from the European Research Council (Advanced and Synergy), the Nature journal award for outstanding scientific contribution, and the Marie Sklodowska-Curie Award in Physics from the Polish Academy of Sciences. Moreover, he received funding from the FOCUS and TEAM programmes of the Foundation for Polish Science and won the 2021 FNP Prize, which is considered the most important scientific award in Poland.

Pierre Kervella (born in 1973 in Annonay, France) is a Professor of Astronomy at Laboratory for Space Science and Astrophysical Instrumentation (LESIA), Paris Observatory at PSL Research University.

Prof. Pierre Kervella_fot. Laurence Honnorat_s

Prof. Pierre Kervella_photo: Laurence Honnorat

His research interests include Cepheids and the cosmic distance ladder, high-precision astrometry for stellar and exoplanet physics, and mass loss of red supergiants.

Kervella completed a double master?s degree in astrophysics and space science and in mechanical engineering at the University of Paris. There, he also defended his doctoral thesis and received professorship. He has won numerous awards and grants, organized several prestigious scientific conferences and authored nearly 250 publications (including four in Nature and one in Science).

Besides scientific work, Kervella is involved in educational and advisory activities: he was director of education at the Paris Observatory from 2019 to 2021 and an advisor to the European Commission from 2007 to 2020.