Related papers: Bipolar rings from jet-inflated bubbles around evo…
The morphologies of planetary nebula have long been believed to be due to wind shaping processes in which a fast wind from the central star impacts a previously ejected envelope. Asymmetries assumed to exist in the slow wind envelope lead…
We study the dynamics of stellar wind bubbles around hydrogen-deficient stars using numerical simulations with time- and ion dependent cooling. We consider two types of hydrogen-deficient stars, massive WR stars, producing Ring Nebulae, and…
We calculate the X-ray emission from the shocked fast wind blown by the central stars of planetary nebulae (PNs) and compare with observations. Using spherically symmetric self similar solutions, we calculate the flow structure and X-ray…
By conducting three-dimensional (3D) hydrodynamical simulations we find that jets that a main sequence companion launches as it orbits inside the wind acceleration zone of an asymptotic giant branch (AGB) star can efficiently remove mass…
We conduct a three-dimensional hydrodynamical simulation to study the interaction of two opposite inclined jets inside the envelope of a giant star, and find that the jets induce many vortexes inside the envelope and that they efficiently…
Using a code that employs a self-consistent method for computing the effects of photo-ionization on circumstellar gas dynamics, we model the formation of wind-driven nebulae around massive stars. We take into account changes in stellar…
We present a semi-analytic model for shaping the nebula around eta Carinae that accounts for the simultaneous production of bipolar lobes and an equatorial disk through a rotating surface explosion. Material is launched normal to the…
We present a model for the formation of massive ($M > 10 M_\odot$) stars through accretion-induced collisions in the cores of embedded dense stellar clusters. This model circumvents the problem of accreting onto a star whose luminosity is…
Planetary nebulae often have asymmetric shapes, which could arise due to collimated jets from evolved stars before evolution to the planetary nebula phase. The source of jet collimation in these stars is unknown. Magnetic fields are thought…
We explore a new, efficient mechanism that can power toroidally magnetized jets up to two to three times their original terminal velocity after they enter a self-similar phase of magnetic acceleration. Underneath the elongated outflow lobe…
We carry out high resolution two-dimensional radiation-hydrodynamic numerical simulations to study the formation and evolution of hot bubbles inside planetary nebulae (PNe). We take into account the evolution of the stellar parameters, wind…
In this paper we explore the dynamics of ionization bounded planetary nebulae after the termination of the fast stellar wind. When the stellar wind becomes negligible, the hot, shocked bubble depressurizes and the thermal pressure of the…
I discuss some observational properties of aspherical nebulae around massive stars, and conclusions inferred for how they may have formed. Whether or not these ideas are applicable to the shaping of planetary nebulae is uncertain, but the…
Massive protostars attain high luminosities as they are actively accreting and the radiation pressure exerted on the gas in the star's atmosphere may launch isotropic high-velocity winds. These winds will collide with the surrounding gas…
We explore the observational characteristics of jet-driven supernovae by simulating bipolar-jet-driven explosions in a red supergiant progenitor. We present results of four models in which we hold the injected kinetic energy at a constant…
We present three-dimensional hydrodynamic simulations of the interaction of a slow wind from an asymptotic giant branch(AGB) star and a jet blown by an orbiting companion. The jet or "Collimated Fast Wind" is assumed to originate from an…
I derive constraints on jet properties for inflating pairs of bubbles in planetary nebulae and clusters of galaxies. This work is motivated by the similarity in morphology and some non-dimensional quantities between X-ray-deficient bubbles…
Non-axisymmetric features are found in the core collapse of a rapidly rotating massive star, which might have important implications for magnetic field amplification and production of a bipolar outflow that can explode the star, as well as…
Massive stars in young massive clusters insert tremendous amounts of mass and energy into their surroundings in the form of stellar winds and supernova ejecta. Mutual shock-shock collisions lead to formation of hot gas, filling the volume…
We present new binary stellar evolution models that include the effects of tidal forces, rotation, and magnetic torques with the goal of testing Planetary Nebulae (PNe) shaping via binary interaction. We explore whether tidal interaction…