Millimeter and submillimeter interferometry allows to probe the environment around evolved massive stars, where optical and NIR studies might be severely limited by large extinctions due to dusty environments. We present here the morphology and kinematics of the molecular envelope around the red supergiant star VY CMa. We have used the Submillimeter Array (SMA) to map the $^{12}$CO(J=2–1) line and 1.3 mm continuum emissions with an unprecedent resolution of $<$ 2″ or 3000 AU. While the line emission presents a roughly circular shape with a radius of $\sim$ 6000 AU, the velocity structure is markedly different from that of a simple spherically expanding shell. In particular, there is a significant velocity gradient in the East-West direction, confirming the presence of a bipolar outflow.

We model the highly axisymmetric planetary nebula M2-9 using a global 3-D MHD simulation. We assume that there is no high-density circumstellar gas around M2-9, because termination shocks are missing at the top of the bipolar lobes in optical images. The overall structure of our MHD solution is a self-consistent consequence of the stellar wind itself, corresponding to two kinds of circumstellar gas distributions, one a collimated flow and the other enveloping the collimated flow. Thus our model shows a ‘solitary stellar wind’ forming in a diluted circumstellar gas density.

We present preliminary conclusions derived from the analysis of a sample of galactic PNe with [WC]-type central stars (WCPNe) observed with Spitzer/IRS. We report the detection of double-dust (C-rich and O-rich) chemistry in all stars in the sample for which a good S/N spectrum was obtained. Our observations reveal that the simultaneous presence of oxygen and carbon-rich dust features in the infrared spectra of WCPNe is not restricted to late/cool [WC]-type stars, as previously suggested in the literature, but it is found to be a common feature associated to all WCPNe. In particular, mixed chemistry is observed in at least seven early/hot WCPNe in the sample. Various scenarios are proposed to interpret the results obtained in the framework of the chemical evolution of PNe.

In this work we attempt to find Planetary Nebulae(PNe) belonging to the thick disk population of the Galaxy, based on the proper motion and radial velocity data of the objects available in literature, by using a simulation and Bayesian likelihood analysis. Making use of the established kinematical properties of the thick disk/thin disk/halo (TD/D/H) population of the Galaxy, we compute likelihoods of TD/D/H membership of 66 nebulae by fully taking into account the uncertainties associated with their proper motion and radial velocity data. We find 12 candidate PNe whose probability of belonging to the thick disc is 80% or greater, of which 9 PNe have a TD membership probability greater than 90%. Spectroscopy of the TD candidates is being planned and we hope this will shed light on the chemical characteristics of the TD population of the Galaxy, in the context of Planetary nebulae.

Near-infared images from a NICMOS survey revealed the circumstellar matter around several proto-planetary nebulae (PPNe), including IRAS 18184–1623, AFGL 4106, and HD 179821 (=IRAS 19114+0002). The IRAS 18184 data was previously analyzed by O'Hara et al. (2003). Here we present the data on the other two objects.

The true nature of HD 179821 is still a subject of some debate. It could be a yellow hypergiant or a post-AGB star. Regardless, the NICMOS images show that it is surrounded by a nebula with a diameter of $\sim12^{\prime\prime}$. Until 1600 years ago, it was losing mass at a rate of 3 $\times 10^{-4}$ M$_{\odot}$ yr$^{-1}$. It now exhibits multiple concentric shells with small bipolar outer protuberances.

AFGL 4106 was known previously as a spectroscopic binary, consisting of a luminous F-type post-red-supergiant and an M-type red supergiant. It is surrounded by a faint nebula with a diameter of $\sim3^{\prime\prime}$. Here we present the first image that shows not only the nebula but also the binary companion. It appears at a position angle of $\sim270^{\circ}$ and a separation of 0.$^{\prime\prime}$3.

Planetary Nebula (PN) shells and AGB circumstellar envelopes evolve under a wide range of external conditions, from the high ISM densities found in the Galactic plane, to the rarefied and hot intracluster medium where the systemic velocity of the star can be as high as 2000 km $s^{-1}$. We explore the effects that the external pressure and/or stellar systemic velocity have on the observable properties of PNe. We investigate how the mass and size of the PN halos are reduced when the star is moving with respect to the external medium. We have studied as well how the mass of the circumstellar envelope is fed by ISM material when high ISM densities characteristic of the Galactic plane are considered. By studying the evolution of PNe in the intracluster medium in Virgo, we infer shorter PN lifetimes than what is usually adopted. This has important implications, since the assumed PN lifetime strongly affects the fraction of intracluster light derived from PN studies.

In the course of our abundance studies over the past decade we have accumulated more than 120 high-quality, medium resolution spectra of planetary nebulae (PNe) from 3600-9600 Å using the KPNO 2.1m Goldcam CCD spectrograph and the CTIO 1.5m RC spectrograph. Results have been published in, e.g., Kwitter & Henry (1998); Henry, Kwitter & Balick (2004); and Milingo et al. (2006). We have created this website as a place where the spectra are available for graphical display, and where PN atlas information and image links are tabulated. The URL is: http://oit.williams.edu/nebulae

We present the main results derived from a chemical abundance analysis carried out on a large sample of massive galactic O-rich AGB stars (M $>$ 3$-$4 M$_\odot$). Combining these results with previous studies made on a similar sample of luminous AGB stars belonging to the Magellanic Clouds we provide strong observational evidences that metallicity effects are playing a more important role than generally assumed in chemical evolution models. This concerns not only the onset of the so-called “hot bottom burning”, the efficiency of the third dredge-up and the s-process nucleosynthesis as derived from our optical observations, but also the dust production efficiency and the chemical properties of the dust grains in the shell, as inferred from the available infrared data. We find Li overabundances in the galactic stars studied, indicating that they are actually “hot bottom burning” AGB stars. Similar Li overabundances are also observed in the most luminous Magellanic Cloud AGB stars. However, the AGB stars in our galactic sample are not enriched in Zr, in contrast to what is observed in the Magellanic Clouds. In addition, many stars in the galactic sample appear heavily obscured in the optical, suggesting a much more efficient dust production and/or stronger mass loss rates which eventually can be translated into shorter AGB lifetimes.

The discovery of $\sim$500 planetary nebulae (PNe) in the bulge region allows us to probe the bulge out to $\sim8$ kpc. This opens up the possibility to track bulge-disc interactions to unprecedented details. We present an exploration of bulge dynamics with Nbody models of a triaxial bulge embedded in an exponential disc (Peyaud 2005).

We present a population synthesis calculation to derive the total number of planetary nebulae (PNe) in the Galaxy from single stars and binaries. By combining the most up-to-date literature results regarding galactic and stellar formation and evolution, we determined the total number of PNe with radii $<$0.8 pc deriving from single stars and binaries to be 46 000$\pm$15 000. By using common envelope (CE) calculations and observational results of main sequence binaries, we predict that 5 000$\pm$1 600 post-CE PNe with radii $<$0.8 pc exist in the Galaxy today. We compare these predictions with the observationally-based estimate of 7 200$\pm$1 800 PNe in the Galaxy with radii $<$0.8 pc. This suggests that many single stars do not produce PNe and that 69$\pm$28% of PNe we observe derive from CE interactions on the Asymptotic Giant Branch (AGB).

Since the last IAU symposium on planetary nebulae (PNe), several deep spectroscopic surveys of the relatively faint optical recombination lines (ORLs) emitted by heavy element ions in PNe and H II regions have been completed. New diagnostic tools have been developed thanks to progress in the calculations of basic atomic data. Together, they have led to a better understanding of the physical conditions under which the various types of emission lines arise. The studies have strengthened the previous conjecture that nebulae contain another component of cold, high metallicity gas, which is too cool to excite any significant optical or UV CELs and is thus invisible via such lines. The existence of such a plasma component in PNe and possibly also in H II regions provides a natural solution to the long-standing problem in nebular astrophysics, i.e. the dichotomy of nebular plasma diagnostics and abundance determinations using ORLs and continua on the one hand and collisionally excited lines (CELs) on the other.

Using the Cloudy_3D code (Morisset, this conference), we run a set of models to build a catalog of emission line profiles of PNe. The goal is to cover the main morphologies (spherical, ellipsoidal, bipolar, thin or thick shells) and to compute profiles changing the orientation of the nebula, the expansion velocity law (including or not turbulence), the position/size of the aperture. The results is a huge set of profiles and PV-diagrams that can be compared to observations as a help to derive morpho-kinematical properties of real objects.

About 500 MASH(Macquarie/AAO/Strasbourg H$\alpha$ planetary nebula project) PNe were discovered towards the galactic bulge (Parker et al. 2006). For 405 MASH PNe with a diameter $<$ 35 arcsec, we obtain surface brightness, diameter and dynamical age of the nebulae. From line intensity ratios of 133 GBPN observed with the 6dF device, we obtain their density and ionized mass, and their central star temperatures. We discover 15 bipolar and/or nitrogen-rich GBPNe having probably massive stellar progenitors (Peyaud, 2005).

Interaction with the Interstellar Medium (ISM) cannot be ignored in models of PN evolution and shaping. As first pointed out by Villaver et al. (2003 ApJ 585 L49), this interaction begins during the AGB phase. We have run extensive sets of 3D simulations, from the beginning of the AGB superwind until the end of the PN phase to study this interaction. We find ISM interaction strongly affects the outer structures. The simulations predict parsec-size shells to be common. The structure and brightness of ancient PNe is largely determined by the ISM interaction during the AGB and the majority of PNe will have tail structures.

The value of the $\alpha$ ratio, the number of PNe per unit bolometric luminosity in a galaxy, is computed using stellar population synthesis models covering the whole range of Hubble types of galaxies.

Model predictions are compared with the PNe counts in the Local Group, which indicate a fairly constant value of $\alpha$ – between 1 and 6 PNe per 10$^7$ solar luminosities – along the Hubble sequence.

A programme is currently underway to study the structures and kinematics of planetary nebulae known to contain close-binary central stars. Images and high-resolution spectroscopy are presented of the collimated nebula Abell 63 and the ring-like nebula Sp 1. A spatio-kinematical model shows that Abell 63 has a tube-like structure, which has the same inclination as the orbital plane of the central binary system. Kinematic data reveal that Sp 1 is not a hollow sphere, but a tube-like nebula viewed pole-on.

We present 1.6-4.7 $\mu$m images of PPNe and young PNe recently obtained with the Keck Adaptive Optics (AO) system. These observations provide higher angular resolution and probe deeper into the dusty envelopes of post-AGB objects than HST images and, therefore, show with unprecedented detail the morphology of these nebulae. Some objects have limb-brightened lobes displaying a remarkable point-like symmetry, which suggests the presence of underlying precessing jets that may be carving out the nebular lobes. Our images also show a very rich structure at the very small scale of $\sim$0.” 1, including jet-like features, arcs, searchlight beams, as well as faint, extended halos in a number of objects.

The recent on-line availability of large-scale, wide-field surveys of the Galaxy and Magellanic Clouds in several optical and near/mid-infrared passbands has provided unprecedented opportunities to refine selection techniques and eliminate contaminants in PN surveys. This has been coupled with new surveys offering improved detection rates via higher sensitivity and resolution. This will permit more extreme ends of the PN luminosity function to be explored and enable studies of under represented PN evolutionary states. Known PNe in our Galaxy and LMC have thus been significantly increased over the last few years due primarily to the advent of narrow-band imaging in important nebula lines such as H$\alpha$, [O iii] and [S iii]. These PNe are generally of lower surface brightness, larger angular extent, in more obscured regions and in later stages of evolution than those in most previous surveys. A more representative PN population for in-depth study is now available, particularly in the LMC where the known distance adds considerable utility for derived PN parameters. Future prospects for Galactic and LMC PNe research are briefly highlighted.

Detached shells can be identified from their NIR & MIR colours. We use this to identify PPN candidates, including three like IRAS 18455+0448. These are 19178+1206, 18470+0015 & 18123+0511.

We present the latest observational results on the halo PN, H 4–1 (PN G049.3+88.1). The H$_{2}$ 1–0 S(1) 2.122 $\mu$m emission image of H 4–1 showed the existence of an equatorial disk with two outer arcs in this object. In order to reveal the internal kinematics making this complex structure, we performed spatial and spectral high-resolution spectroscopy with the HDS (High Dispersion Spectrograph) of the Subaru 8.2m telescope. The HDS observational results showed the presence of a high-velocity ($\ge$ 40 km s$^{-1}$) collimated outflow.