Seminaria

"Copernicus’s Mathematical Astronomy in "De revolutionibus": A Very Short Introduction"

Jarosław Włodarczyk (Institute for the History of Science, PAN, Warsaw)

Nicolaus Copernicus (1473–1543) propelled one of the greatest revolution in science and his heliocentric cosmology radically changed the relationship between man and the universe. However, to prove his concept of cosmos, Copernicus had to create mathematical models of the movements of planets. He devoted five of the six books of his "De revolutionibus" (On the Revolutions, 1543) to this task. As he himself argued, “mathematics is written for mathematicians”. In my lecture I shall outline Copernicus’s mathematical astronomy and its early reception in the form of the first Copernican astronomical tables which allowed to calculate the positions of the planets for any time.

"A multiphase study of theoretical and observed light curves of classical Cepheids in the Magellanic Clouds"

Felipe Espinoza Arancibia (NCAC, Warsaw)

We present an analysis of the theoretical and observed light-curve parameters of the fundamental mode (FU) classical Cepheids in the Magellanic Clouds in V- and I- photometric bands. The state-of-the-art 1D non-linear radial stellar pulsation (RSP) code in MESA (MESA-RSP) has been utilized to generate the theoretical light curves using four sets of convection parameters. Theoretical light curves with two chemical compositions: Z = 0.008 and Z = 0.004 appropriate for the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC), respectively, covered a wide range of periods (3 1), and all periods. The multiphase relations obtained from theoretical and observed light curves in the PL/PC/AC plane are found to be dynamic in nature, with the effect more pronounced at Φ ~ 0.75-0.85. Furthermore, a contrasting behaviour of the theoretical/observed multiphase PL and PC relations between the short and long periods has been found for both LMC and SMC. The analysis shows that multiphase PL relations are more stringent to test the models with observations over the FPs. Distances to the LMC/SMC determined using long period Cepheids are found to be in good agreement with the literature values when the term R21 is added to the PL relation.

K. Kurbah et al., MNRAS (2023)