Seminarium odbywa się w środy o 11:15 w warszawskim oddziale Centrum Astronomicznego lub w wersji online na platformie Zoom. Językiem wykładowym jest angielski; seminarium prowadzi dr Stanisław Bajtlik (bajtlik@camk.edu.pl). Zapraszamy również osoby spoza Centrum Astronomicznego. W sprawie szczegółów technicznych prosimy kontaktować się e-mailowo z dr. Stanisławem Bajtlikiem.
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.
Journal Club odbywa się w poniedziałki o 11:15 w Sali Seminaryjnej warszawskiego Centrum Astronomicznego. Językiem wykładowym jest angielski. Spotkania prowadzą koordynatorzy Journal Club. Osoby zainteresowane wygłoszeniem prezentacji zachęcamy do kontaktowania się poprzez email: journalclub(@camk.edu.pl).
Gergely Hajdu (NCAC, Warsaw)
based on https://ui.adsabs.harvard.edu/abs/2026ApJ...998L..27V/abstract from van Dokkum et al. (Feb 2026).
