We present a systematic observational study of 32 PNe that present point-symmetric structures, multiple bipolar outflows or other related features.

Planetary nebulae (PNe) in the Magellanic Clouds (LMC, SMC) offer a unique opportunity to study both the population and evolution of low- and intermediate-mass stars in an environment which is free of the distance scale bias that hinders Galactic PN studies. The emission shown by PNe in the 5–40 $\mu$m range is characterized by the presence of a combination of solid state features (from the dust grains) and nebular emission lines superimposed on a strong dust continuum. We acquired low resolution IRS spectroscopy of a selected sample of LMC and SMC PNe whose morphology, size, central star brightness, and chemical composition are known. The data have been acquired and reduced, and the IRS spectra show outstanding quality as well as very interesting features. The preliminary analysis presented here allows to determine strong correlations between gas and dust composition, and nebular morphology. More detailed analysis in the future will deepen our knowledge of the mass-loss mechanism, its efficiency, and its relation to PN morphology.

We have observed the X-ray brightest planetary nebula BD +30° 3639 with the new Japanese astronomical satellite Suzaku. With its superior spectral resolution back-illuminated CCD camera, a blend of K-lines from highly ionized C, N, O elements are successfully resolved into individual species, and an extremely high relative abundance ratio of C/O $\sim$ 40 is obtained. This strongly suggests the direct measurement of the helium shell-burning products.

We are preparing a catalog of extragalactic planetary nebulae. The current number of entries is $\sim$8,000 objects, with the largest samples coming from the Local Group (SMC, LMC, M33, and M31), but with representation from over 55 galaxies. The catalog is expected to be complete in late 2007.

We present VLA (Very Large Array) observations of the 1720, 1667, 1665 and 1612 MHz OH maser emission from the central region of K 3–35. Circular polarization was found in the 1720, 1665, and 1612 MHz transitions. An estimate of the magnitude of the magnetic field, derived from the 1665 lines, toward this young planetary nebula is $\sim$ 0.14 mG at a radius of $\sim$ 250 AU.

We present the results of a small mid-infrared imaging survey of planetary nebulae. Of 21 objects observed 19 were resolved. Only in NGC 6210 was there a marked contrast between the dust morphology and the emission line morphology. For all the other objects the dust and the gas must be well mixed even in the faint lobes of bipolar objects such as Fg3, Pe1-7, and NGC 6881.

We report on our studies of the physical structure of the planetary nebula (PN) NGC 7662. Using (3D) Integral Field Spectroscopy we have been able to measure the electron temperature more accurately and at a larger number of radial locations than before. Here we briefly present our method by which we find a strong positive temperature gradient with increasing radius. According to hydrodynamic models a hot halo, when compared to the central star, can be the product of the passage of an ionization front (e.g. Marten 1993). Such a gradient is not found in equilibrium models, and this finding – when confirmed for other objects – strongly advocates the use of hydrodynamic models when modeling PN halos.

Here we are reporting the detection of HCO$^+$ ($J=1\rightarrow 0$) emission as well as weak emission of CO($J=1\rightarrow 0$) toward the planetary nebula (PN) K 3-35 as a result of a molecular emission survey carried out toward this source. K 3-35 is remarkable because it is one of the two PNe that are known to exhibit water maser emission. In this nebula, the emission is present in the central region as well as at a distance of $\simeq$ 5000 AU away from the center. The presence of molecular emission reveals some clues that could lead to the understanding of the persistence of water molecules in its envelope. We also report new spectra of the CO ($J=2\rightarrow 1$) transition. From the CO emission we have obtained a value for the excitation temperature of the molecular gas of $\simeq$ 20 K. Using this result, we have estimated a molecular mass for the envelope of $\simeq$0.017 $M_{\odot}$, and that the abundance for the HCO$^{+}$ is 6.1 $\times 10^{-7}$.

We present results of a quantitative spectral analysis of a sample comprising eleven hydrogen deficient post-AGB stars of the spectral type PG 1159 with state-of-the-art NLTE model atmospheres. For all objects high resolution spectra obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) are available. The FUV spectra of PG 1159 stars are dominated by lines of helium, carbon and oxygen, and for the first time we also identified lines of several trace elements as sulfur and silicon which allow to determine the abundances of light metals in the atmospheres of these stars. As these stars show nuclear processed former intershell matter on their surface, the determined abundances also allow us to constrain the predictions of evolutionary models and element abundances in AGB stars.

HST multi-epoch images and VLT integral-field, high resolution spectroscopy allowed us a robust determination of the 3-D geometry and orientation of the nebula surrounding He 2-147, and to measure its apparent expansion in the plane of the sky. Applying the expansion parallax method results in a distance which is significantly shorter that the one obtained via the period-luminosity (P-L) relationship for the Mira component. We show how allowing for shock excitation of the nebula, as suggested by the extremely broad nebular line profiles, enables both distance derivations to be reconciled.

We report preliminary results of a spectral line survey of NGC 7027 in the $\lambda$ 3 mm and 1.3 mm bands using the Arizona Radio Observatory (ARO) 12-m and 10-m telescopes. To a sensitivity limit of $\sim$10-20 mK, we have detected 34 lines, including hydrogen recombination lines and rotational transitions of CN, CO, CCH, CO$^+$, HCO$^+$, and their isotopes.

We developed a new quick pseudo-3D photoionization code based on Cloudy (Ferland et al.) and IDL (RSI) tools. The code is running the 1D photoionization code Cloudy various times, changing at each run the input parameters (e.g. inner radius, density law) according to an angular law describing the morphology of the object. Then a cube is generated by interpolating the outputs of Cloudy. In each cell of the cube, the physical conditions (electron temperature and density, ionic fractions) and the emissivities of lines are determined. Associated tools (VISNEB and VELNEB_3D) are used to rotate the nebula and to compute surface brightness maps and emission line profiles, given a velocity law and taking into account the effect of the thermal broadening and eventually the turbulence. Integrated emission line profiles are computed, given aperture shapes and positions (seeing and instrumental width effects are included). The main advantage of this tool is the short time needed to compute a model (a few tens of minutes).

We have studied the emission from the core of the Butterfly Nebula. We have tried to interpret the Balmer line profiles, double lines in emission. These profiles are not only observed in M2-9, but are also present in other objects of similar morphology.

During an ongoing search for small planetary nebulae in the southern hemisphere 24 candidates have been found and spectroscopically observed in a region of 45 square degrees.

We report on the progress of our on-going campaign to monitor the evolution of the VLTP objects V4334 Sgr and V605 Aql, as well as the suspected (V)LTP object CK Vul. V4334 Sgr does not show signs of increased ionization compared to our previous observations in 2004. We obtained the first radio detection of V605 Aql, indicating a strong increase in radio flux since 1987. We also present the first radio detection of CK Vul and discuss the expansion of the material ejected during the 1670 event.

Using the [O III] 5007 Planetary Nebula Luminosity Function (PNLF) distance indicator, we can double the number of known distances to nearby Type Ia SNe, and hence improve their zero point calibration while searching for systematic offsets in SN Ia luminosities between young populations (spiral galaxy) and old populations (ellipticals). We report three new PNLF distances and two new lower limits for five galaxies (NGC 524, 1316, 1380, 1448, & 4526) that have hosted well-observed Type Ia SNe. From the PNLF, we find a Hubble constant of 75 km/s/Mpc, whereas we derive H$_0$=72 from Cepheids and H$_0$=73 from SBF.

A better understanding of the nature of the molecular and ionized gas envelopes of planetary nebulae (PNe) is important both to our understanding of their contribution to the ISM and to the evolution of PNe themselves. Using HST's unprecedented resolution and sensitivity for near-IR observations, we are studying the distribution and intensity of molecular gas emission from PNe.

Hydrodynamical simulations played an important role in understanding the dynamics and shaping of planetary nebulae in the past century. However, hydrodynamical simulations were just a first order approach. The new millennium arrived with the generalized understanding that the effects of magnetic fields were necessary to study the dynamics of planetary nebulae. Thus, B-fields introduced a whole new number of physical possibilities for the modeling. In this paper, we review observational work done in the last 5 years and several works on the magnetohydrodynamics of proto-planetary nebulae, since all the effort has been focused on that stage, and discuss different scenarios for the origin of magnetized winds, and the binary-bipolarity relation.

We present 0.18$^{\prime\prime}$ resolution mid-infrared images of OH231.8+4.2 using the Gemini South telescope. The images show a bright central core of $\sim$1$^{\prime\prime}$ in size, with extended emissions in the lobes. We find evidence for different chemical composition of the dust in the core and the lobes from the narrow-band images.

The high-excitation planetary nebula NGC 7009 and its central star were observed with the Far Ultraviolet Spectroscopic Explorer (FUSE) through a 30$\,{\times}\,$30 arcsec (LWRS) aperture, and with the HIRS narrow slit (1.25$\,{\times}\,$20 arcsec) to isolate the inner and outer parts of the nebula from the central star. The high-resolution (15 km/s) nebular spectra (910-1187 Å) show strong emission from C III] and permitted transitions of He II N II, N III, S III, S IV, S VI and O VI, with stronger emission closer to the central star. In this paper we present results obtained on the spatial variation of these tracers of highly ionized gas. The hot central star of NGC 7009 is discussed in a separate paper by Sonneborn et al.