Felipe Espinoza Arancibia

Centrum Astronomiczne im. M. Kopernika PAN

Sesja VI: Gwiazdy, układy gwiazd oraz materia międzygwiazdowa

Czwartek 14.09.2023 11:15 – 11:28

abstrakt:
The instability strip (IS) of classical Cepheids has been extensively studied theoretically. Comparison of the theoretical IS edges with those obtained empirically, using the most recent Cepheids catalogs available, can provide us with insights into the physical processes that determine the position of the IS boundaries. We investigate the empirical positions of the IS of the classical Cepheids in the Large Magellanic Cloud (LMC) using data of classical fundamental-mode and first-overtone LMC Cepheids from the OGLE-IV variable star catalog, together with a recent high-resolution reddening map from the literature. We studied their position on the Hertzsprung-Russell diagram and determined the IS borders by tracing the edges of the color distribution along the strip. The results obtained show a break located at the Cepheids’ period of about 3 days, which was not reported before. This phenomenon adds complexity to the typically assumed shape of the IS.
Furthermore, our empirical borders show good agreement with theoretical ones published in the literature. This proves that our empirical IS is a useful tool to put constraints on theoretical models.