Related papers: Formation of a rapidly rotating classical Be-star …
Some contracting or expanding stars are thought to host a large-scale magnetic field in their radiative interior. By interacting with the contraction-induced flows, such fields may significantly alter the rotational history of the star.…
We study the dynamics of a star orbiting a merging black-hole binary (BHB) in a coplanar triple configuration. During the BHB's orbital decay, the system can be driven across the apsidal precession resonance, where the apsidal precession…
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…
Long-term evolution of a stellar orbit captured by a massive galactic center via successive interactions with an accretion disc has been examined. An analytical solution describing evolution of the stellar orbital parameters during the…
Rotation is thought to be a major factor in the evolution of massive stars, especially at low metallicity, with consequences for their chemical yields, ionizing flux and final fate. Determining the natal rotation-rate distribution of stars…
The formation of a star is a dynamic process fed by the gravitational collapse of a molecular cloud core. Theoretical models and observations suggest that the majority of this infalling material settles into a protoplanetary disk before…
We report on a mechanism which may lead to a spin-up of the surface of a rotating single star leaving the Hayashi line, which is much stronger than the spin-up expected from the mere contraction of the star. By analyzing rigidly rotating,…
It is usually accepted to consider an apsidal motion in binary stars as a direct confirmation that a substance inside stars is not uniformly distributed. It is shown in this paper that the apsidal motion in binary systems observation data…
We study the angular momentum evolution of binaries containing two white dwarfs which merge and become cool helium-rich supergiants. Our object is to compare predicted rotation velocities with observations of highly evolved stars believed…
We consider the gas dynamics in an accreting binary system of degenerate stars within the framework of the Newtonian approximation. In such a system, the accretion stream can impact the surface of a white dwarf (WD) or neutron star (NS) as…
Rapid rotation in field red giant stars is a relatively rare but well-studied phenomenon; here we investigate the potential role of planet accretion in spinning up these stars. Using Zahn's theory of tidal friction and stellar evolution…
In the past decade, a consensus has emerged regarding the nature of classical Be stars: They are very rapidly rotating main sequence B stars, which, through a still unknown, but increasingly constrained process, form an outwardly diffusing…
Accretion is the prime mode of star formation, but the exact mode has not yet been identified in the Herbig Ae/Be mass range. We provide evidence that the the maximum variation in mass-accretion rate is reached on a rotational timescale,…
The attracting properties of gravity enable matter present in cores to collapse into stars with seven orders of magnitude change in space and time making modelling of star formation a challenging multi-scale process. To circumvent this…
The understanding of the rotational evolution of early-type stars is deeply related to that of anisotropic mass and angular momentum loss. In this paper, we aim to clarify the rotational evolution of rapidly rotating early-type stars along…
Studies of stellar magnetism at the pre-main sequence phase can provide important new insights into the detailed physics of the late stages of star formation, and into the observed properties of main sequence stars. This is especially true…
Using the formalism of general relativity for axially symmetric gravitational fields and their sources - rotating compact stars - a perturbation theory with respect to angular velocity is developed and physical quantities such as mass,…
Close stellar binaries are prone to undergo a phase of stable mass transfer in which a star loses mass to its companion. Assuming that the donor star loses mass along the instantaneous interstellar axis, we derive the orbit-averaged…
We compare the angular momentum extracted by a wind from a pre-main-sequence star to the torques arising from the interaction between the star and its Keplerian accretion disk. We find that the wind alone can counteract the spin-up torque…
We investigate the gas structures around young binary stars by using three-dimensional numerical simulations. Each model exhibits circumstellar disks, spiral arms, and a circumbinary disk with an inner gap or cavity. The circumbinary disk…