We developed a self-consistent stellar-nebular model for NGC 7009. This model reproduces the available observations ranging from optical to UV. The combined approach to the modeling process produces more constraints and thus more trustworty results. After obtaining the model, we perform a comparative study of the chemical composition of He, N, O, Ne, Cl, and S in the nebula and its central star. Concluding that the stellar composition agrees with the nebular composition with t2 ≠ 0.00.

A review of some earlier exact analytic solutions of monochromatic stationary vector radiative transfer equation in homogeneous infinite medium is given. It is stressed that Green's functions for plane-parallel, spherical and cylindrical symmetry are expressed through derivatives and integrals from basically one and the same set of functions.

Explicit expressions for the differential operator of stationary quasi-monochromatic polarized radiative transfer equation in Euclidean space with piecewise homogeneous real part of the effective refractive index are obtained in circular cylindrical, prolate spheroidal, elliptic conical, classic toroidal and simple toroidal coordinate system.

We have used the SuperCOSMOS Hα Survey to look for faint outer structures such as halos, ansae and jets around known planetary nebulae across 4000 square degrees of the southern Milky Way. Our search will contribute to a more accurate census of these features in the Galactic PN population. Candidate common-envelope PNe have also been identified on the basis of their microstructures. We also intend to determine more reliable distances for these PNe, which should allow a much better statistical basis for the post-AGB total mass budget. Our survey offers fresh scope to address this important issue.

We present preliminary results obtained from the analysis of very deep echelle spectra of a dozen planetary nebulae with [WC] or weak emission lines (wels) central stars. The computed abundance discrepancy factors (ADFs) are moderate, with values lower than 4. In principle, no evidence of the H-poor metal enriched inclusions proposed by Liu et al. (2000) have been found. However, a detailed analysis of the data is in progress.

The 3-D and kinematic structure of the Eskimo nebula, NGC 2392, has been notoriously difficult to interpret given its complex morphology, multiple kinematic components and its nearly pole-on orientation along the line of sight. Here we present the most comprehensive high resolution spectroscopic mapping of the Eskimo planetary nebula to date. The data consist of 21 spatially resolved, long-slit echelle spectra tightly spaced over the Eskimo and along its bipolar jets. This data set allowed us to construct a velocity-resolved [NII] channel map of the nebula with a resolution of 10 km/s that disentagles the differente kinematic components of the nebula and reveals clearly for the first time the kinematic expansion pattern for each of the components. The spectroscopic information is combined with a HST image to construct the first detailed three dimensional model of the Eskimo with the code SHAPE. With this model we demostrate that the Eskimo is nearly a twin to the Saturn nebula, but rotated 90° to the line sight. Furthermore, we show that the main characteristics of our model apply to the general properties of the group of elliptical planetary nebulae with ansae, once the orientation is considered.

The Local Group dwarf irregular galaxy IC 10 is the nearest starburst galaxy (at 725 kpc) and presents extended and complex HI kinematics. It is believed that IC 10 is still experiencing an intense and very recent burst of star formation, likely triggered by infalling gas from an extended envelope which is counter-rotating with respect to the galaxy proper rotation. In this contribution we summarize our preliminary results (Gonçalves et al. 2011, in prep.) obtained by performing a kinematic analysis of the PN population of IC 10. Our aim is to explore the kinematic connection of its intermediate to old stellar populations with that obtained from HI observations. Some PNe were found at large galactocentric distances and could therefore represent a trace of past tidal interactions.

Dwarf galaxies are crucial to understand the formation and evolution of galaxies, since they constitute the most abundant galaxy population. Abundance ratios and their variations due to star formation and inflow/outflow of gas are key constraints to chemical evolution models. The determination of these abundances in the dwarf galaxies of the Local Universe is thus of extreme importance. NGC 185 is one of the four brightest dwarf companions of M31, but unlike the other three it has an important content of gas and dust. Interestingly enough, in an optical survey of bright nearby galaxies NGC 185 was classified as a Seyfert galaxy based on its integrated emission-line ratios in the nuclear regions. However, although its emission lines formally place it in the category of Seyfert it is probable that this galaxy does not contain a genuine active nucleus. In this contribution, we resume, firstly, our results of an empirical study of the galaxy, on which we characterise its emission-line population and obtain planetary nebulae abundance ratios (Gonçalves et al. 2012). And, secondly, we discuss our attempt to identify the possible ionization mechanisms for NGC 185 enlighting the controversial classification of this galaxy dwarf spheroidal (dSph) as well as Seyfert, via stellar population synthesis and chemical evolution modelling (Martins et al. 2011).

We present preliminary results from low resolution spectroscopic observations of planetary nebulae located in the southern Milky Way disk.

We report on the ongoing study of the infrared properties of different types of planetary nebulae based on the data from recent photometric and spectroscopic infrared surveys. We present our first results concerning the relation between nebular morphology and infrared properties using the observations from the AKARI mission.

Kn 26 is a recently identified planetary nebula (PN). To confirm its nature and study its spatio-kinematical structure, we have obtained high spatial-resolution optical and near-IR narrowband images, high-dispersion long-slit echelle spectra, and intermediate-resolution spectroscopic observations. The new data confirm the PN nature of Kn 26 and reveal features typical of bipolar PNe: hourglass morphology, H2 emission, and nitrogen enrichment. A detailed analysis of its morphology and kinematics, however, suggests the presence of one additional pair of bipolar lobes that would make Kn 26 a new member of the class of quadrupolar PNe.

We present XMM-Newton and Chandra observations of the born-again planetary nebula A 30. These X-ray observations reveal a bright unresolved source at the position of the central star whose X-ray luminosity exceeds by far the model expectations for photospheric emission and for shocks within the stellar wind. We suggest that a “born-again hot bubble” may be responsible for this X-ray emission. Diffuse X-ray emission associated with the petal-like features and one of the H-poor knots seen in the optical is also found. The weakened emission of carbon lines in the spectrum of the diffuse emission can be interpreted as the dilution of stellar wind by mass-loading or as the detection of material ejected during a very late thermal pulse.

We present new observations in the radio continuum of 31 planetary nebulae at 5 and 8 GHz with the Australian Telescope Compact Array. The observations are used to invesigate properties of the interstellar extinction toward Galactic Bulge.

We discuss the results of the search for [WR] central stars in binary systems. GLMP 160 is the first [WR] central star in a binary system known. We analyze photometry, spectroscopy and imaging of this system.

We carefully consider numerous explanations for the sulfur abundance anomaly in planetary nebulae. No one rationale appears to be satisfactory, and we suggest that the ultimate explanation is likely to be a heretofore unidentified feature of the nebular gas which significantly impacts the sulfur ionization correction factor.

We present chemical evolution models for the dwarf irregular NGC 6822, using chemical abundances of Planetary Nebulae (PNe) and HII regions and also the mass of gas (Mgas) as observational constraints. Chemical evolution models have been calculated to reproduce the abundances as derived from both, collisionally excited lines (CELs) and recombination lines (RLs). In our models, the chemical contribution of low and intermediate mass stars (LIMS) is time delayed, while for the massive stars the chemical contribution is instantaneous, as in Franco & Carigi (2008). The chemical contribution of SNIa is included in our model, thus we are also able to reproduce the observational Fe/H abundance obtained from A stars.

We report the optical and infrared studies of a sample of five new planetary nebulae (PNe) in the IPHAS and DSH catalogues. The PN status of these objects was confirmed by optical narrow-band imaging and low resolution spectroscopy. One object (IPHASX J195248.8+255359) is found to be a bipolar PN with faint Hα lobes and a bright core in [O iii].

We have analyzed the HST images of ten young planetary nebulae (PNe) and found them to possess multipolar structures. Concentric arcs and 2-D rings are also found in some objects.

Production of multicharge ions due to generation of hot expanding plasma blobs, short-living “compound particles”, at high-velocity collisions between dust grains of a planetary nebula and dust particles of the interstellar medium is analytically considered. Dependence of the multiplicity of charge of produced ions on the relative velocity of colliding dust particles is determined.

A trigonometric parallax distance is measurable for a planetary nebula if it harbors H2O (or OH) maser spots. We have demonstrated it for H2O maser sources, K3-35, IRAS 19312+1950 and IRAS 18286-0959 using the VLBI Exploration of Radio Astrometry (VERA). They are post-AGB stars and exhibit peculiar morpho-kinematical structures like a bipolar planetary nebula or a bipolar molecular jet (water fountain). The luminosities and secular motions of these sources derived from the trigonometric distances and proper motions of the H2O masers suggest that their parental stars may be intermediate-mass (2M⊙ < M* < 8 M⊙) evolved stars.