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We argue that outward transport of energy by convection and photon diffusion in a common envelope evolution (CEE) of giant stars substantially reduces the fraction of the recombination energy of hydrogen and helium that is available for…
We discuss an evolutionary dark energy model, based on the presence of non-equilibrium effects on the dark energy constituents, which are described via a bulk viscosity contribution. We implement the proposed dynamics by the analysis of the…
Both rotation and interactions with binary companions can significantly affect massive star evolution, altering interior and surface abundances, mass loss rates and mechanisms, observed temperatures and luminosities, and their ultimate…
We briefly summarize the impact of the chemical peculiarities associated to the multiple population phenomenon in Galactic Globular Clusters, on the evolutionary properties and spectral energy distribution of second generation stars, in…
Common-envelope (CE) evolution is an outstanding open problem in stellar evolution, critical to the formation of compact binaries including gravitational-wave sources. In the ``classical'' isolated binary evolution scenario for double…
The discovery via gravitational waves of binary black hole systems with total masses greater than $60M_\odot$ has raised interesting questions for stellar evolution theory. Among the most promising formation channels for these systems is…
We present a comparative study between the results of most hydrodynamic simulations of the common envelope binary interaction to date and observations of post common envelope binaries. The goal is to evaluate whether this dataset indicates…
Be stars are rapidly rotating B type stars. The origin of their rapid rotation is not certain, but binary interaction remains to be a possibility. In this work we investigate the formation of Be stars resulting from mass transfer in…
Asymptotic giant branch (AGB) stars play a significant role in our understanding of the origin of the elements. They contribute to the abundances of C, N, and approximately $50\%$ of the abundances of the elements heavier than iron. An…
Although planets have been found orbiting binary systems, whether they can survive binary interactions is debated. While the tightest-orbit binaries should host the most dynamically stable and long-lived circumbinary planetary systems, they…
We calculate the orbital evolution of binary systems where the primary star is an evolved red giant branch (RGB) star, while the secondary star is a low-mass main sequence (MS) star or a brown dwarf. The evolution starts with a tidal…
In the era of advanced electromagnetic and gravitational wave detectors, it has become increasingly important to effectively combine and study the impact of stellar evolution on binaries and dynamical systems of stars. Systematic studies…
Stellar astrophysicists are increasingly taking into account the effects of orbiting companions on stellar evolution. New discoveries, many thanks to systematic time-domain surveys, have underlined the role of binary star interactions in a…
Binary stars are pairs of stars that are gravitationally bound, providing in some cases accurate measurements of their masses and radii. As such, they serve as excellent testbeds for the theory of stellar structure and evolution. Moreover,…
We study dynamics of $\Lambda(t)$ cosmological models which are a natural generalization of the standard cosmological model (the $\Lambda$CDM model). We consider a class of models: the ones with a prescribed form of…
We investigate the common envelope binary interaction, that leads to the formation of compact binaries, such as the progenitor of Type Ia supernovae or of mergers that emit detectable gravitational waves. In this work we diverge from the…
In this paper we emphasize the close connection between the chemical and spectrophotometric evolution of stellar systems: Chemical yields from stars correspond to a precise fraction of their emitted light. We translate this concept…
It is now clear that central star binarity plays a key role in the formation and evolution of planetary nebulae, with a significant fraction playing host to close-binary central stars which have survived one or more common envelope…
The current gravitational wave (GW) detectors have successfully observed many binary compact objects, and the third generation ground-based GW detectors such as Einstein telescope and space-borne detectors such as LISA will start their GW…
There are important but unresolved processes in the standard formation scenarios of double compact star binaries (DCBs; BH-BH, BH-NS, NS-NS systems), such as mass transfer and the common envelope (CE) phase. We analyze the effects of…