For M1-91 we find that the ratio of the 6717/6731 [S II] narrow band images shows two symmetrical very collimated high density regions, or jets, along the major axis.

We infer many properties of M 1-92 from the similarity of the spectral features with the symbiotic star MWC 560. We show that M 1-92 could also have a jet along the major axis and that from the NW knot we receive scattered light from the central region that has traveled along the line of symmetry.

Supersonic and even hypersonic outflows have been found in a wide variety of PNe using the Manchester Echelle spectrometer (MES; Meaburn et al. 1984). Dramatic examples of these extreme motions found over many years are highlighted here for comparison with their most recent discovery in the bipolar PN, MyCn 18.

In 1997 and 1998 we observed 16 PN with the ESO 1.4 m CAT telescope, in the Hα and [NII] lines. We selected 9 PN with fairly symmetric line profiles, these PN we analyzed with the “Torun codes”.

We have recently completed a comprehensive analysis of the morphological and kinematical properties of ~ 50 PNe which are known to possess low-ionization (micro)structures (LISs; Gonçalves et al. 2001). This study has shown that density is a crucial parameter for distinguishing among several physical processes responsible for their formation and evolution.

We are at present analysing long-slit, medium-resolution optical spectra of 18 PNe in order to determine the physical parameters of the LISs and their environments. These data were obtained with the 1.5 m Danish (ESO) and the 2.5 m Isaac Newton (ORM) telescopes.

Here we show the first results of this survey, presenting the density variation of NGC 7009 and comparing it with the derived densities of K 4-47 and Wray 17-1.

Recently, high-resolution imaging surveys of young planetary nebulae (PNe) and protoplanetary nebulae (PPNe) have revealed that the majority of these objects are characterised by multipolar bubbles distributed roughly point-symmetrically around the central star (e.g. Sahai & Trauger 1998, Sahai 2000). Sahai & Trauger (1998) have proposed that episodic high-speed jet-like outflows, operating during the protoplanetary or very late-AGB phase, are the primary agent for shaping PNe. OH and H2O masers provide a unique and crucial probe of the kinematics of the circumstellar material in PPNe, because of the general lack of other emission-line diagnostics. Here we present new results from our ongoing study of PPNe using HST images with interferometric OH & H2O maser-line data to unravel their detailed spatio-kinematic structure (e.g. Sahai et al. 1999a, Sahai, Claussen, & Morris 2002).

Using a sample of 29 bipolar Planetary Nebulae (BPNe) we show correlations between the luminosity and SED shape with the inclination to the line of sight of the objects polar axes. The presence of an equatorial “doughnut” of material around the central object can explain both these correlations and also and the bipolar shape.

In this paper, the Helix nebula (NGC 7293) is postulated to be a fractal describable by a Julia set. In order to support this hypothesis, a cometary filament is chosen from the periphery of the shell and is analyzed using an automated software. The box dimension of NGC 7293 is found to be 1.841059.

Using Hα images from the Southern H-Alpha Sky Survey Atlas (SHASSA) we have discovered a “cometary tail” of ionized matter extending at least 30 arcmin from the main body of the planetary nebula Sh 2-68 (PN G030.6+06.2). This tail is aligned with the proper motion of the central star and is obviously a contrail of material left behind by Sh 2-68 moving in a Galactic Disk orbit. The tail's existence is a direct confirmation of Sh 2-68's interaction with the interstellar medium (ISM) and highlights the possibly important role of the ISM's magnetic field.

We have applied the “Torun models” to the PN Wray 16-423, and found evidence for an embedded shock in the nebula.

The central star V4334 Sgr (Sakurai's Nova) of the planetary nebula PN G010.4+04.4 underwent in 1995–1996 the rare event of a very late helium flash shell burning. The rapid formation of a dust shell allows a precise model, basing on the dust formation history instead of the commonly used average dust formation rate and mass loss. The model applies a complete dust grain size distribution, and transiently heated grains. Only the fitting of the visual light curve gives already the complete spectral energy distribution (SED) model. No adjustment with the infrared data points is needed.

XSHAPE has been developed to aid the better understanding of the 3D morphologies and kinematics of PNe and novae, by producing models which closely predict the observed 2D images and long-slit spectra of these objects. Early successes include plausible simulations for the elliptical PN Sa 2-21 and the nova HR Del.

An observational program for study dynamics of planetary nebulae with the help of RRL is discussed. The expansion velocities may be found from observations of radio recombination lines in different wavelength. The method is free of the microturbulence problem inherent in standard spectroscopic methods. Set of theoretical models was computed for NGC 7027. Observations of RRL with n > 150 may allow making choice between models with high and low microturbulence.

Optical spectra and images in the main optical emission lines were obtained for 21 type I planetary nebulae (PNe). IR images directed towards the detection of shocked molecular hydrogen were secured in 17 of these objects. No evidence of shocked H2 could be found in A 14 and Sh 2-71, and its existence needs to be confirmed in JnEr 1 and M 1-57. Bipolarity is obvious in most of these sources. A 24, JnEr 1 and M 3-5 may be bipolars seen nearly pole-on. The chemical composition of nearly half of these objects indicates that third dredge-up episodes may have occured in their progenitor star. The presence of shock waves in the ionized component is inferred in 9 PNe, where the temperature ratio T(O+2)/T(N+) is large and the Hα/[S II]6724 line ratio small, a typical combination in shock excited plasmas. A larger sample of type I PNe shows that small Hα/[S II]6724 line ratios are usually associated with large temperature ratios.

Multiwavelength and multitechnique observations towards NGC 6309 are presented. The data consist of λ3.6-cm continuum, ground- and space-based imaging, and high and low-dispersion longslit spectra. The structure of the central region seems to be a distorted, ring of 20″ in diameter. The lack of [N II] emission is conspicuous, as revealed by imaging and low dispersion spectra. Notably, the kinematics of the point-symmetric (PS) structures of NGC 6309 indicates the presence of lobes or cavities as those generally found in bipolar nebulae. The results lead to conclude that the origin of this peculiar morphology is not related to BRETs, but rather to that of a bipolar PN with PS structures in its lobes.

This is a short report on the study of internal motions of selected Planetary nebulae. We have studied this subject with both high (4 or 8 Å/mm) and intermediate (20 Å/mm) dispersion spectrographs. During the course of this work we noticed the existence of a high velocity gas flow distinct from the well known expanding gas, but with smaller velocities than stellar winds (Yadoumaru & Tamura 1994 on Abell 30; Otsuka & Tamura, 2001 on H 4-1). We present subsequent results obtained with the intermediate dispersion spectrograph about 10 selected planetary nebulae. The analyses were made by multiple Gaussian method on the emission line profiles of Hα. High velocity gas flows were recognized by a weak broad wing component.

The origin of the wide range of morphologies observed in planetary nebulae (PNe) is not well established. The influence of a binary companion of the central star can naturally explain this variety of morphologies, but very few PNe have known binary central stars. The evolution of the binary system with mass loss may result in the displacement of the central star from the nebular center. The large sample of PNe observed by HST is being used to search for de-centered central stars. Preliminary results indicate that the occurrence of de-centered central stars is widespread among all morphological types of PNe.

IC 4634 is a planetary nebula with a striking point-symmetric morphology. Strings of line-emitting knots, particularly bright in [N II] emerge from its bright Hα core. These strings bend in opposite directions on either side of the nucleus. We have obatined sub-arcsecond monochromatic imagery that neatly reveals its main morphological components. Additionally, we also present a comprehensive kinematic mapping of the nebula, consisting of several long-slit echelle positions across the main components of the nebula.

High resolution spectroscopic data of a sample consisting of 24 planetary nebulae (PNe) with WR-type nuclei ([WC]) from the list of Tylenda et al. (1993) plus 1 late-[WC] presented by De Marco et al. (2001), and 7 PNe with weak emission line stars (WELS) nuclei listed in Tylenda et al. (1993) are analyzed. The data were collected using the 2.1 m telescope at the Observatorio Astronómico Nacional, San Pedro Mártir, México and were used to determine the expansion velocity (Vexp) of the gaseous component in each sample object in the following ions: [N II]λA6584, [O II]λ3729, [O III]λA5007, Hβ, HeI λ5876, and HeII λ4686. A sample of 8 non-WR type (typical) PNe were observed as a controlo sample. All observational data were systematically gathered using the REOSC Echelle Spectrograph on 1995 July 29–31, 1996 June 14–17, 1997 August 3–4, 1998 December 11–14, 1999 October 4–7, and 2000 November 1–3. In order to take the highest Vexp of the gesous component in each ion, it was taken the half width of the line at one tenth of the maximum intensity when the line featured either a single Gaussian profile or a Gaussian with extended wings profile. For two-peaks profiles, Vexp was measured taking into account both the peak-to-peak displacement and the HW of the lines.

Up to now, ten planetary nebulae are regarded as halo planetary nebulae (halo PNe). We obtained low- and moderate-dispersion spectra of the spatially resolved halo planetary nebula H4-1 in the wavelength region of λλ3700-6800 Å with the Cassegrain Spectrograph of 74-inch telescope at Okayama Astronomical Observatory. In the moderate dispersion observation, we were able to obtain [O III] λλ4959,5007 and Hα of H4-1 at several position angles (P.A.). The image was spatially resolved and its apparent angluar size should be less than 10″.0.

Recent applications of PN to the study of galactic chemical evolution are reviewed, such as PN and stellar populations, abundance gradients, including their space and time variations, determination of the He/H radial gradient and of the helium-to-metals enrichment ratio, and the [O/Fe] x [Fe/H] relation in the solar neighbourhood and in the galactic bulge.