Weronika Narloch (CAMK, Warsaw)
Since its discovery by Henrietta Swan Leavitt, the period-luminosity relation (also known as the Leavitt Law) for pulsating stars has been a useful tool for measuring cosmic distances. Over time, it has become a crucial rung of the so-called extragalactic distance ladder, important for measuring the famous Hubble constant, which can be interpreted as the rate of expansion of the universe. For this reason, period-luminosity relationships have become the object of interest for the Araucaria group. In this talk, I would like to present our recent efforts to calibrate these relations for different types of pulsating stars in our Galaxy, in the Sloan bands.
Amit Kumar Mandal (Center for Theoretical Physics, Polish Academy of Science, Warsaw)
This talk will focus on understanding the innermost structure of Active Galactic Nuclei (AGNs), which cannot be resolved by any existing imaging techniques, through multi-wavelength observations. The flux variability of AGN serves as a powerful tool to map the extent of both the dusty torus and the broad line region (BLR) surrounding the central supermassive black hole (SMBH). Reverberation mapping (RM) is a key technique that enables estimates of SMBH mass (M_BH) across a range of redshifts. RM relies on measuring the time delay between variations in the continuum emission and the corresponding response from the line-emitting gas and the reprocessed torus emission. In this talk, I will focus on constraining the torus size-luminosity relation in AGNs by utilizing optical data from ground-based surveys such as ASAS-SN, CRTS, PTF, and ZTF, along with infrared data from the Wide-field Infrared Survey Explorer (WISE) in the W1 and W2 bands. Additionally, I will briefly discuss accretion disk continuum reverberation mapping, which helps to determine the size of the continuum-emitting region in the accretion disk and its correlation with key AGN parameters, including luminosity and accretion rate.
Knut Olsen (NOIRLab, Arizona)
I will present an overview of the Vera C. Rubin Observatory project and its planned Legacy Survey of Space and Time (LSST), scheduled to start in 2025. The overview will include LSST’s science goals, the status of the construction project, the plans for operations (including the role of the Rubin In-Kind program), and the planned observing strategy.
Arkadiusz Orłowski (Department of Artificial Intelligence, Institute of Information Technology, SGGW, Warsaw)
Thibault Boulet (Institute of Astrophysics and Space Sciences, University of Porto, Portugal)
Understanding the Milky Way's formation and evolution requires precise stellar age determination across its components. Recent advances in asteroseismology, spectroscopy, stellar modeling, and machine learning, along with all-sky surveys, have provided reliable stellar age estimates. We aim to furnish accurate age assessments for the Main Red Star Sample within the APOGEE DR17 catalogue. Leveraging asteroseismic age constraints, we employ machine learning to achieve this goal. We explore optimal non-asteroseismic stellar parameters, including Teff, L, [C/N], [Mg/Ce], [α/Fe], U(LSR), and 'Z' vertical height from the Galactic plane, to predict ages via categorical gradient boost decision trees. Our model, trained on merged samples from TESS and APOKASC-2 catalogs, achieves a median fractional age error of 20.8%, with a relative difference between the learning curves of 4.77%. For stars older than 3 Gyr, the error ranges from 7% to 23%; for those between 1 and 3 Gyr, it is 26% to 28%; and for stars younger than 1 Gyr, it is 43%. Applied to 125,445 stars, our analysis confirms the flaring of the young Galactic disc and reveals an age gradient among the youngest Galactic plane stars. We also identify two groups of metal-poor ([Fe/H] < -1 dex) and young (Age < 2 Gyr) stars exhibiting peculiar chemical abundances and halo kinematics. One of these groups is likely a remnant of the third gas infall episode that started around 2.7 Gyr ago.
Piotr Wielgórski (CAMK PAN, Warsaw)
