Juan Pablo Hidalgo (University of Rome)
Large-scale magnetic fields have been observed in about 10% of main-sequence early-type stars. Notably, chemically peculiar Ap/Bp stars can host surface magnetic fields with mean strengths between 200 G and 30 kG. Unlike late-type stars, whose magnetic fields have complex geometries and are likely generated by convective dynamos, the observed magnetic fields of early-type stars have simpler geometries, and are stable over long timescales, with virtually no variability over several decades. Because these stars have thick radiative envelopes and convective cores, surface dynamos are unlikely to account for the observed magnetism. Consequently, the origin of these magnetic fields remains uncertain. In this talk, I will review recent progress in some of the main theories proposed to explain the magnetism in early-type stars, exploring dynamos hosted by their convective cores, and their interaction with fossil fields inherited from earlier evolutionary stages. Furthermore, I will discuss ongoing simulations of pre-main-sequence stellar evolution aimed at constraining the structure and properties of these primordial fields.
Bogumił Pilecki (CAMK, Warsaw)
Since 2020, we have been systematically identifying and characterizing double-lined (SB2) binary Cepheids in the Large Magellanic Cloud, the Small Magellanic Cloud, and the Milky Way. Our primary detection method exploits the apparent overbrightness of Cepheids as a signature of a luminous companion, complemented by searches for systems composed of two Cepheid components. This effort has increased the known sample of confirmed SB2 Cepheids to 62 objects —an order-of-magnitude improvement over previous numbers— and expanded the number of double-Cepheid binaries from one to ten. For 37 systems, we detected anticorrelated orbital motion of both components, providing definitive proof of binarity. Preliminary orbital solutions have been derived for 24 systems with periods up to seven years, and full spectroscopic orbits have been determined for 15 systems with periods up to 3 years. I will present the orbital and physical properties of these binaries and discuss their implications for Cepheid multiplicity, evolution, and origin. Remarkably, at least 10% of them exhibit evidence of past mergers, suggesting that a significant fraction of Cepheids may form through binary interaction. I will also address the possible consequences of these findings for calibrating the Cepheid distance scale.
Leda Berni (INAF- Osservatorio Astrofisico di Arcetri (Florence, Italy))
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.
Dominika Król (Harvard Smithonian CfA)
Maciek Wielgus (Instituto de Astrofísica de Andalucía, IAA-CSIC, Granada, Hiszpania)
Laetitia Gibaud (Department of Physics, University of Białystok)
Samik Mitra (Astrophysics and Relativity Group International Centre for Theoretical Sciences, Bengaluru, India)
