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Seminarium środowe



15.04.2026

"Star formation efficiencies in core-collapse supernovae"

Martin Solar (Adam Mickiewicz University, Poznań)

Core-collapse supernovae are very energetic explosions that have a significant impact in the interstellar medium within galaxies. However, it is not well understood how progenitors of core-collapse supernovae form, evolve, and explode. In this talk, I plan to constrain the core-collapse supernova progenitor properties studying their star formation efficiency (or molecular gas depletion time) environments. In summary, it is found that interacting massive binaries occur in regions of intense, efficient star formation rather than simply higher gas content.


22.04.2026

"State transitions in Changing-Look AGNs"

Biswaraj Palit (CAMK PAN, Warsaw)

The changing-look (CL) behavior in active galactic nuclei (AGNs) is characterized by dramatic fluctuations in the overall brightness of sources, leading to restructuring of circum-nuclear environments such as the inner accretion geometry, broad line region (BLR), and outflows. They offer a rare opportunity to witness accretion state transitions in real time, akin to those seen in stellar-mass X-ray binaries (XRBs). In this talk, I will present a decade long multiwavelength study of the Seyfert galaxy, which captures a complete spectral state transition--from a faint, hard X-ray phase to a bright, UV- and soft X-ray-dominated state within just $\sim$10 years. Using diagnostics like the X-ray loudness parameter ($\alpha_{\rm OX}$) and the hardness-intensity diagram (HID), we identify a critical Eddington ratio ($\lambda_{\rm Edd} \sim 0.02$) marking the onset of inner accretion flow restructuring. These findings provide strong evidence that CLAGNs trace accretion physics analogous to XRBs, scaled up in mass but compressed in time.


29.04.2026

"The Sun and Its Active Cousins: Magnetic Activity Across Late-Type Stars"

Kamil Bicz (University of Wrocław)

Magnetic activity in late-type stars includes a variety of phenomena driven by the interaction between convection, rotation, and magnetic field generation. Using the Sun as a reference, I will discuss how the physical processes change as we look at lower-mass, faster-rotating stars. This includes the transition from partially to fully convective stars, occurring around spectral types M3–M4. I will present results from starspot modeling of active late-type stars, comparing spot temperatures, sizes, and distributions with those of the Sun. Finally, I will focus on stellar flares, which are the most energetic expressions of magnetic activity. I will demonstrate how flare occurrence, energy, and physical parameters can differ from the values seen in the Sun.


06.05.2026

"tba"

Przemysław Mróz (Astronomical Observatory, Warsaw University)


13.05.2026

"TBA"

Maciek Wielgus (Instituto de Astrofísica de Andalucía, IAA-CSIC, Granada, Hiszpania)


20.05.2026

"What Are We Learning About Super-Eddington Accretion Disks From Simulations?"

Patrick C. Fragile (Charleston College)

Accretion of gas onto black holes is one of the most important processes shaping our Universe. Understanding extremely high rates of accretion (dubbed `super-Eddington') is vital to explaining the challenging observation that supermassive black holes (SMBHs) are fully formed at redshifts >7. It is also important to understanding astrophysical objects such as tidal disruption events (TDEs) and ultra-luminous X-ray sources (ULXs). While we are able to perform observations of super-Eddington accreting systems, to understand them more fully, we must turn to numerical studies. In this talk, I will present the results of some recent super-Eddington disk simulations and discuss some of the interesting things we are learning.


27.05.2026

"tba"

Bogumił Pilecki (CAMK, Warsaw)


03.06.2026

""

Samik Mitra (Astrophysics and Relativity Group International Centre for Theoretical Sciences, Bengaluru, India)