Related papers: From Bipolar to Elliptical: Morphological Changes …
Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). A binary companion is increasingly gaining support as a…
Astrophysical outflows treated initially as spherically symmetric often show evidence for asymmetry once seen at higher resolution. The preponderance of aspherical and multipolar planetary nebulae (PN) and pre-planetary nebulae (PPN) was…
During the last years, many observational studies have revealed that binaries play an active role in the shaping of non spherical planetary nebulae. We review the different works that lead to the direct or indirect evidence for the presence…
Bipolar planetary nebulae (PNe) are thought to result from binary star interactions and, indeed, tens of binary central stars of PNe have been found, in particular using photometric time-series that allow detecting post-common envelope…
The transition from Asymptotic Giant Branch star to Planetary Nebula is short-lived and mysterious. Though it lasts only a few thousand years, it is thought to be the time when the asymmetries observed in subsequent phases arise. During…
Despite numerous efforts, the transition from Asymptotic Giant Branch (AGB) stars to Planetary Nebulae (PN) is a poorly understood phase of stellar evolution. We have therefore carried out interferometric (VLA) radio observations of a…
In this paper, a time-dependent magnetohydrodynamic model is presented which aimed at understanding the superwind production by an evolved AGB star and the consecutive formation of a dense circumstellar envelope around it. We know…
Planetary Nebulae (PNe) have been used satisfactory to test the effects of stellar evolution on the Galactic chemical environment. Moreover, a link exists between nebular morphology and stellar populations and evolution. We present the…
Since various structural components of planetary nebulae manifest themselves differently, a combination of optical, infrared, submm, and radio techniques is needed to derive a complete picture of planetary nebulae. The effects of projection…
We show that there are strong links between certain types of asymmetrical Planetary Nebulae (PNe) and symbiotic stars. Symbiotics are binaries and several have extended optical nebulae all of which are asymmetrical and ~-40% are bipolar.…
We discuss the formation of globules in planetary nebulae, typified by those observed in the Helix Nebula. We show that the properties of the globules, their number, mass, separation, and overall geometry strongly support a scenario in…
At the end of their lives low mass stars such as our Sun lose most of their mass. The resulting planetary nebulae show a wide variety of shapes, from spherical to highly bipolar. According to the generalized interacting stellar winds model,…
As mass-losing asymptotic giant branch (AGB) stars evolve to planetary nebulae (PNe), the mass outflow geometries transform from nearly spherical to extreme aspherical. The physical mechanisms governing this transformation are widely…
Planetary nebulae (PNe) can be roughly categorized into several broad morphological classes. The high quality images of PNe acquired in recent years, however, have revealed a wealth of fine structures that preclude simplistic models for…
This paper explores the effects of post-AGB winds driven solely by magnetic pressure from the stellar surface. It is found that winds can reach high speeds under this assumption, and lead to the formation of highly collimated…
We present new analytical solutions for the dynamics of planetary nebulae. These equations consider the temporal variation of the mechanical luminosity as well as the common envelope evolution scenario. By comparing a database of nebulae…
We review work on the evolution of planetary nebulae and proto-planetaries via magneto-rotational mechanisms showing that a dynamo generated magnetic field can produce the energy and momentum needed to drive pPN and PNe outflows. Angular…
Bipolar expansion at various stages of evolution has been recently observed in a number of AGB stars. The expansion is driven by bipolar jets that emerge late in the evolution of AGB winds. The wind traps the jets, resulting in an…
We conduct 2D numerical simulations of jets expanding into the slow wind of asymptotic giant branch stars. We show that the post-shock jets' material can explain the observed extended X-ray emission from some planetary nebulae (PNs). Such…
With the use of high-resolution ALMA observations, complex structures that resemble those observed in post-AGB stars and planetary nebulae are detected in the circumstellar envelopes of low-mass evolved stars. These deviations from…