Related papers: Counteracting Tidal Circularization with the Grazi…
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…
Stars are generally spherical, yet their gaseous envelopes often appear non-spherical when ejected near the end of their lives. This quirk is most notable during the planetary nebula phase when these envelopes become ionized. Interactions…
I discuss the relationship between mass loss and nucleosynthesis on the Asymptotic Giant Branch (AGB). Because of thermal pulses and possibly other mixing processes, products of nucleosynthesis can be brought to the surface of AGB stars,…
Binary post-asymptotic giant branch (post-AGB) stars are products of a poorly understood binary interaction process that occurs during the AGB phase. These systems comprise of a post-AGB primary star, a main-sequence secondary companion and…
We conduct 3D numerical simulations of the winds collision process in the massive binary system Eta Carinae, and conclude that accretion occurs during periastron passage. We include radiative cooling of the two winds, one from each star,…
The binary characteristics of asymptotic giant branch (AGB) stars are imprinted in the asymmetric patterns of their circumstellar envelopes. We develop a simple method for constraining the orbital parameters of such binary stars from the…
We study how tides in a binary system induce some specific internal shear mixing, able to substantially modify the evolution of close binaries prior to mass transfer. We construct numerical models accounting for tidal interactions,…
Binarity is believed to dramatically affect the history and geometry of mass loss in AGB and post-AGB stars, but observational evidence of binarity is sorely lacking. As part of a project to look for hot binary companions to cool AGB stars…
It is generally acknowledged that the mass loss of Asymptotic Giant Branch (AGB) stars undergoes variations on different time scales. We constructed models for the dust envelopes for a sample of AGB stars to assess whether mass-loss…
I suggest the existence of an extended zone above the surface of asymptotic giant branch (AGB), as well as similar stars experiencing high mass loss rates. In addition to the escaping wind, in this zone there are parcels of gas that do not…
Observations suggest that many, if not all, post AGB systems evolve through an aspherical outflow phase. Such outflows require a sufficient engine rotational energy which binaries can provide. Via common envelope evolution, binaries can…
In this introduction to the Third Congress of Vienna on AGB stars I first try to highlight why it is so hard to cope with the AGB evolutionary phase. This phase is indeed dominated by three main physical processes concerning bulk motions of…
Current implementations of the stellar atmosphere typically derive boundary conditions for the interior model from either grey plane-parallel atmospheres or scaled solar atmospheres, neither of which can be considered to have appropriate…
We study systems of close orbiting planets evolving under the influence of tidal circularization. It is supposed that a commensurability forms through the action of disk induced migration and orbital circularization. After the system enters…
Using recent results on the operation of turbulent dynamos, we show that a turbulent dynamo can amplify a large scale magnetic field in the envelopes of asymptotic giant branch (AGB) stars. We propose that a slow rotation of the AGB…
We perform the first systematic study on how dynamical stellar tides and general relativistic (GR) effects affect the dynamics and outcomes of binary-single interactions. For this, we have constructed an N-body code that includes tides in…
A rich zoo of peculiar objects forms when Asymptotic Giant Branch (AGB) stars, undergo interactions in a binary system. For example, Barium (Ba) stars are main-sequence and red-giant stars that accreted mass from the outflows of a former…
We study the tidal evolution of a binary system consisting of a 1.4 Msun compact object in elliptic orbit about a 10 Msun uniformly rotating main sequence star for various values of the initial orbital parameters. We apply our previously…
Many astrophysical binaries, from planets to black holes, exert strong torques on their circumbinary accretion disks, and are expected to significantly modify the disk structure. Despite the several decade long history of the subject, the…
Common envelope evolution (CEE) is believed to be an important stage in the evolution of binary/multiple stellar systems. Following this stage, the CE is thought to be ejected, leaving behind a compact binary (or a merger product). Although…