ﻻ يوجد ملخص باللغة العربية
We present a new extended and detailed set of models for Classical Cepheid pulsators at solar chemical composition ($Z=0.02$, $Y=0.28$) based on a well tested nonlinear hydrodynamical approach. In order to model the possible dependence on crucial assumptions such as the Mass-Luminosity relation of central Helium burning intermediate-mass stars or the efficiency of superadiabatic convection, the model set was computed by varying not only the pulsation mode and the stellar mass but also the Mass-Luminosity relation and the mixing length parameter that is used to close the system of nonlinear hydrodynamical and convective equations. The dependence of the predicted boundaries of the instability strip as well as of both light and radial velocity curves on the assumed Mass-Luminosity and the efficiency of superadiabatic convection is discussed. Nonlinear Period-Mass-Luminosity-Temperature, Period-Radius and Period-Mass-Radius relations are also computed. The theoretical atlas of bolometric light curves for both the fundamental and first overtone mode has been converted in the Gaia filters $G$, $G_{BP}$ and $G_{BR}$ and the corresponding mean magnitudes have been derived. Finally the first theoretical Period-Luminosity-Color and Period-Wesenheit relations in the Gaia filters are provided and the resulting theoretical parallaxes are compared with Gaia Data Release 2 results for both fundamental and first overtone Galactic Cepheids.
Classical Cepheids in open clusters are key ingredients for stellar population studies and the characterization of variable stars, as they are tracers of young and massive populations and of recent star formation episodes. Cluster Cepheids are of par
The flux-weighted gravity-luminosity relation (FWGLR) is investigated for a sample of 477 classical Cepheids (CCs), including stars that have been classified in the literature as such but are probably not. The luminosities are taken from the literatu
We present a well-defined and characterized all-sky sample of classical Cepheids in the Milky Way, obtained by combining two time-domain all-sky surveys: Gaia DR2 (Gaia Collaboration et al. 2018) and ASAS-SN (Shappee et al. 2014). We first use parall
In the Gaia era, the membership analysis and parameter determination of open clusters (OCs) are more accurate. We performed a census of OCs classical Cepheids based on Gaia Early Data Release 3 (EDR3) and obtained a sample of 33 OC Cepheids fulfillin
We present homogeneous and accurate iron abundances for almost four dozen (47) of Galactic Cepheids using high-spectral resolution (R$sim$40,000) high signal-to-noise ratio (S/N $ge$ 100) optical spectra collected with UVES at VLT. A significant frac