I will present the newest results from our project which aim is to increase the number of known Cepheids in double-lined binary (SB2) systems from 6 to even 100 or more. Such an increase will allow us, among others, to measure Cepheid masses for a large sample of these important stars. Currently, only 6 accurate masses are available, which hinders our understanding of the physical properties of Cepheids. At the same time, Cepheids are widely used for essential measurements (extragalactic distances, the Hubble constant). Examining Cepheid period-luminosity relations we selected as binary candidates, outlying Cepheids that are too bright for their periods. Up to now, we confirmed 60 as SB2 systems, while for 37 we detected a significant orbital motion of the components.
I will show the preliminary orbits of these systems and summarize their properties. We identified systems with orbital periods even 5 times shorter than the shortest reported before and those with mass ratios significantly different from 1 (suggesting merger events in the past). These features are essential to understanding how multiplicity affects: 1) the creation and destruction of Cepheids’ progenitors, and 2) the global properties of Cepheids. We will also present 9 new systems composed of two Cepheids (only one such system is known), and several wide-orbit systems, that may serve in the future for independent and accurate geometrical distance measurements to other galaxies.
Horarios: December 1, 2023 11:30
Publicado por: Claudia Aguilera