Related papers: ate helium flash in V605 Aql: PNe evolution and sh…
The central star of this nebula has an observed intense magnetic field and the fast wind is no longer present, indicating that a back flow process has probably developed. Long-slit, spatially resolved echelle spectra have been obtained…
Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al. (2015), we undertook deep Halpha imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre…
NGC 1360 is a large planetary nebula (PN) without an obvious shell morphology. We have analyzed H-alpha images and high-dispersion echelle spectra of NGC 1360 in order to construct spatio-kinematic models and to determine its density…
Detached shells are believed to be created during a thermal pulse, and constrain the time scales and physical properties of one of the main drivers of late stellar evolution. We aim at determining the morphology of the detached dust shells…
The commonly accepted mechanism governing the formation of the nascent wind in oxygen-rich AGB stars combines an initial boost above the photosphere, given by shock waves resulting from stellar pulsations and convective cell granulation,…
A spherical planetary nebula is described as a geometric model. The nebula itself is considered as a thin-shell which visualized as a boundary of two spacetimes. The inner and outer curvature tensors of the thin-shell are found in order to…
We present first results of a study of the halo kinematics for a sample of early type galaxies using planetary nebulae (PNe) as kinematical tracers. PNe allow to extend up to several effective radii (Re) the information from absorption line…
This review describes some general properites of proto-planetary nebulae with particular emphasis on the recent work of morpholgical studies. The weight of observational evidence shows that proto-planetary nebulae (PPNe) are most certainly…
The number of plausible associations of extended VHE (TeV) sources with pulsars has been steadily growing, suggesting that many of these sources are pulsar wind nebulae (PWNe). Here we overview the recent progress in X-ray and TeV…
In this brief review, I discuss recent developments in the study of pulsar-powered nebulae ("plerions"). The large volume of data which has been acquired in recent years reveals a diverse range of observational properties, demonstrating how…
We present a 142-ks Chandra observation of the enigmatic combination supernova remnant G310.6-1.6 consisting of a bright pulsar-wind nebula driven by an energetic pulsar, surrounded by a highly circular, very faint shell with a featureless,…
Planetary nebulae (PNe) exist in a range of different morphologies, from very simple and symmetric round shells, to elliptical, bipolar, and even quadrupolar shapes. They present extremely complex ensembles of filaments, knots, ansae, and…
We discuss the basic physical model and the relevant processes responsible for creating and shaping planetary nebulae out of a cool AGB wind envelope. We show that a hydrodynamical treatment along the upper AGB leads quite naturally to more…
We present an infrared (IR) characterization of the born-again planetary nebulae (PNe) A30 and A78 using IR images and spectra. We demonstrate that the carbon-rich dust in A30 and A78 is spatially coincident with the H-poor ejecta and…
V4444 Sgr (Nova Sgr 1999) has been recently suggested to be a possible recurrent nova based on the detection of the preexisting dust, which may have been formed in a previous outburst. We examined this possibility using the available…
FUSE spectroscopy has proved that extremely hot hydrogen-deficient post-AGB stars (PG1159 stars) display matter on their surface that usually remains hidden in the region between the H- and He-burning shells of the former AGB star. Hence,…
The detection and study of molecular gas in born-again stars would be of great importance to understand their composition and chemical evolution. In addition, the molecular emission would be an invaluable tool to explore the physical…
In this paper we explore the evolution of a PWN while the pulsar is spinning down. An MHD approach is used to simulate the evolution of a composite remnant. Particular attention is given to the adiabatic loss rate and evolution of the…
CONTEXT: Until now, only one planetary nebula (PN) has been known in the Fornax dwarf spheroidal galaxy. AIMS: The discovery of a second PN candidate, associated with one of the 5 globular clusters in the Fornax dwarf, is reported. METHODS:…
The remarkable Crab Nebula is powered by an energetic pulsar whose relativistic wind interacts with the inner parts of the Supernova Remnant SN1054. Despite low-intensity optical and X-ray variations in the inner Nebula, the Crab has been…