相关论文: Abell 41: nebular shaping by a binary central star…

We present low and high resolution long-slit spectra of three bipolar planetary nebulae (PNe) with bright central cores: A79, He2-428 and M1-91. He2-428 and M1-91 have high density (from 10^3.3 to 10^6.5 cm^-3) unresolved nebular cores that…

Close binary central stars of planetary nebulae are key in constraining the poorly-understood common-envelope phase of evolution, which in turn is critical in understanding the formation of a wide-range of astrophysical phenomena (including…

We report a multi-wavelength study of two evolved planetary nebulae (PNs) M 2-55 and Abell 2. Deep optical narrow-band images ([O III], H?, and [N II]) of M 2-55 reveal two pairs of bipolar lobes and a new faint arc-like structure. This…

Eight planetary nebulae have been identified as `born-again', a class of object typified by knotty secondary ejecta having low masses ($\sim$$10^{-4}$ M$_{\odot}$) with nearly no hydrogen. Abell 30, the archetype of the class, also belongs…

The shaping of various morphological features of planetary nebulae (PNe) is increasingly linked to the role of binary central stars. Identifying a binary within a PN offers a powerful tool with which to directly investigate the formation…

Planetary nebulae are traditionally considered to represent the final evolutionary stage of all intermediate-mass stars ($\sim$0.7-8Msol). Recent evidence seems to contradict this picture. In particular, since the launch of the Hubble Space…

Using the Planetary Camera on board the Hubble Space Telescope we have measured the projected separation of the binary components in the nucleus of the planetary nebula Abell 35 to be larger than 0.08 arcsecs but less than 0.14 arcsecs. The…

A number of efforts are underway to detect close binary stars in planetary nebulae. The primary goal of these studies is to determine the binary fraction of central stars. The next stage is a detailed analysis of the binaries to determine…

Close binary central stars of planetary nebulae (PNe) must have formed through a common envelope evolution during the giant phase experienced by one of the stars. Transfer of the angular momentum from the binary system to the envelope leads…

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 LMC is ideal for studying the co-evolution of planetary nebulae (PNe) and their central stars, in that the debilitating uncertainties of the Galactic PN distance scale and selection biases from attenuation by interstellar dust do not…

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…

We report the discovery of a planetary nebula centered on the poorly studied symbiotic binary star DT Ser. In a few other symbiotic stars spatially resolved nebulae have been discovered: however, only one of them might be a genuine…

Planetary Nebulae represent a powerful window into the evolution of low-intermediate mass stars that have undergone extensive mass-loss. The nebula manifests itself in an extremely wide variety of shapes, but exactly how the mass lost is…

We have conducted a detailed multi-wavelength study of the peculiar nebula Abell 48 and its central star. We classify the nucleus as a helium-rich, hydrogen-deficient star of type [WN4-5]. The evidence for either a massive WN or a low-mass…

It is now clear that a binary formation pathway is responsible for a significant fraction of planetary nebulae, and this increased sample of known binaries means that we are now in a position to begin to constrain their influence on the…

I list the 16 planetary nebulae (PNe) known to contain close-binary nuclei, and show that the nebulae generally have axisymmetric structures, including elliptical, bipolar, or ring morphologies. The orbital periods range from 2.7 hr to 16…

Abell 70 is a planetary nebula (PN) whose nucleus at optical wavelengths is a G8 star with enhanced carbon and s-process abundances--a "barium star." The cool star is a binary companion of the true, hot central star. In several other…

We conduct three-dimensional hydrodynamical simulations of two opposite jets launched obliquely to the orbital plane around an asymptotic giant branch (AGB) star and within its dense wind, and demonstrate the formation of a `messy'…

The morphology of planetary nebulae emerging from the common envelope phase of binary star evolution is investigated. Using initial conditions based on the numerical results of hydrodynamical simulations of the common envelope phase it is…