We examine the abundance gradient in the Milky Way disk via homogeneously determined data for 124 Galactic planetary nebulae (PNe). We present recent results from a detailed regression analysis of the O gradient. With O, Ne, S, Cl, and Ar available and a range of galactocentric distance (R g ) from 0.9 to 21 kpc, we present additional exploration of the disk radial gradient by statistically analyzing a series of short segments of increasing average R g .

The observational techniques applied to the study of binary stars, brown dwarfs, and exoplanets are summarized in this paper.

The study of the chemical composition of Planetary Nebulae in external galaxies is of paramount importance for the fields of stellar evolution and chemical enrichment history of galaxies. In recent years a number of spectroscopic studies with 6-8m-class telescopes have been devoted to this subject improving our knowledge of, among other, the time-evolution of the radial metallicity gradient in disk galaxies, the chemical evolution of dwarf galaxies, and stellar evolution at low metallicity.

We are extending our search for faint PNe in the LMC to include the outer 56 deg2 area not covered in the original UKST survey of the central 25eg2 region. Candidate PNe have been selected using the Magellanic Cloud Emission Line Survey (MCELS) and the first round of observations has yielded 93 new LMC PNe while confirming the 102 previously known PNe in the outer LMC. We plan to continue our spectroscopic object identification program until we cover all our remaining candidates in the survey area. These observations, providing medium and high resolution spectra from λ3650Å to λ6900Å will additionally be used to measure fluxes for a series of research projects including luminosity functions, abundances and LMC kinematics.

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.

The ESO VLT spectrograph X-shooter is currently the only one capable of observing the range from 330 nm up to 2.5 μm in a single shot. X-shooter is very suitable for study of the many diagnostic emission lines in PN providing a uniform flux scale at medium resolution over a large instantaneous wavelength range. Spectroscopy of two contrasting PNe, NGC 6302 and M 2-9, were observed and methods explored for identification of the many fitted emission lines.

Due to interstellar extinction, optical census of Galactic planetary nebulae (PNs) is highly incomplete, and some compact H ii regions might have been mis-classified as PNs. The problem is particularly severe in the Galactic plane where the extinction in the optical is significant and hampers the detections of PNs. Unlike optical observations, infrared (IR) observations are hardly affected by interstellar extinction, and provide a good opportunity to study highly obscured PNs. In this study, we use the data from the Spitzer Legacy Infrared Mid-Plane Survey Extraordinaire 3D (GLIMPSE 3D) to investigate the mid-infrared (MIR) properties of PNs and PN candidates.

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.

In 2010, we organised a workshop in Tenerife with the aim of bringing together scientists concerned with the completeness and accuracy of atomic data for astrophysical applications. Participants included atomic physicists, theoretical astrophysicists and astronomers, and the workshop covered topics such as the evaluation of uncertainties in atomic data, the propagation of such uncertainties in chemical abundances, and the feedback between observations and calculations. Communication issues were also discussed, including questions such as: How can it be ensured that atomic data are correctly understood and used? Which forum is the best one for a fluid interaction between all communities involved in the production and use of atomic data? This contribution lays out the main issues raised during the workshop and some of the solutions proposed.

Over the last decade Galactic planetary nebula discoveries have entered a golden age due to the emergence of high sensitivity, high resolution narrow-band surveys of the Galactic plane. These have been coupled with access to complimentary, deep, multi-wavelength surveys across near-IR, mid-IR and radio regimes in particular from both ground-based and space-based telescopes. These have provided powerful diagnostic and discovery capabilities. In this review these advances are put in the context of what has gone before, what we are uncovering now and through the window of opportunity that awaits in the future. The astrophysical potential of this brief but key phase of late stage stellar evolution is finally being realised.

GALEX (the Galaxy Evolution Explorer) has provided far-UV(1344-1786Å) and near-UV(1771-2831Å) imaging of several Planetary Nebulae (e.g., Bianchi et al. 2008, Bianchi 2012), with flux limits ~27.5 mag/sq.arcsec for objects in the Medium-deph Imaging Survey (MIS). PNe images in the GALEX broad-band UV filters include flux from both nebular line and continuum emission. We use the GALEX grism observing mode to obtain slitless spectral imaging of a sample of PNe with diameters >1′, in the near-UV. We show the first data from this program. The grism produces 2D images of the prominent UV nebular emission lines, when such lines dominate the flux. Combined with monochromatic images of diagnostic lines in the optical domain, such data help detect and interpret ionization and shock fronts, especially in faint nebular regions.

UBVRI photometry and medium resolution spectroscopy of two Type Ia supernovae, SN 2009an and SN 2009ig, are presented. Their Δm15(B) indicate these two SNe marginally deviate from “normal” Type Ia events. Spectroscopically, both SNe belong to the low velocity gradient group. The estimated mass of 56Ni ejected is almost a factor of two different for these two objects, with the estimates being ~0.4M⊙ for SN 2009an and ~0.8 M⊙ for SN 2009ig.

We have begun new studies of the evolution of thermonuclear runaways (TNRs) in the accreted envelopes of white dwarfs (WDs). Here we focus on the recent outbursts of RS Oph (2006), U Sco (2010) and T Pyx (2011). U Sco explodes about every 10 years and the ejected material from the WD is helium rich. It has a short orbital period for recurrent novae (RNe) but the secondary is likely to be evolved. The WD is thought to be close in mass to the Chandrasekhar limit. T Pyx has just suffered its first outburst since 1966 and it was predicted to never experience another outburst. It has a short orbital period and has formed dust in the ejecta as this paper was being written. One important question is the secular evolution of the WD. Do the repeated outbursts cause the WD to gain or lose mass? If it is gaining mass, it could eventually reach the Chandrasekhar limit and become a Type Ia supernova (SNe Ia) if it can hide the hydrogen and helium in the system. Here, we report on our latest studies of TNRs in accreted envelopes on WDs using a variety of initial WD masses, luminosities, and mass accretion rates. Of great importance to our conclusions, we assume a solar composition (Lodders abundance distribution). We use our 1-D hydro code, NOVA, that includes the Hix and Thielemann nuclear reaction network, the Iliadis reaction rate library, the Timmes equation of state, OPAL opacities, and the new convection of Arnett, Meakin, and Young. We report on the amount of ejected mass, evolution time to explode, and whether or not the WD is growing or losing mass.

We present new determinations of integrated Hα flux for ~1100 Galactic planetary nebulae measured from the Southern H-Alpha Sky Survey Atlas (SHASSA) and its northern counterpart, the Virginia Tech Spectral-Line Survey (VTSS). This catalogue is the largest homogeneous database of its kind, tripling the number of currently available measurements.

Low mass stars in binaries are frequently used as unique tools to determine and establish fundamental stellar parameters. The need for their study and understanding has led to developing new instruments, new observational techniques and improved theoretical models. The relatively recent discovery of exoplanets and their study as the low-mass constituents around other stars is now opening new horizons in binary research. Here, I examine the most common observational challenges in studying low mass binaries across the electromagnetic spectrum.

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.

In the last years (metallicity-dependent) radiation-hydrodynamics simulations have become a powerful tool to understand the formation and evolution of PNe in terms of simple morphologies and kinematics. Contrary to photoionization models, with their ad-hoc assumptions on structure and physics, the RHD models are self-consistent with respect to their density distribution, velocity field, chemical composition, and stellar evolution. We use our models as simple proxies for real PNe and investigate the reliability of common abundance determination methods, which are based on either plasma diagnostics or static photoionization (PI) models.

The four known O(He) stars are the only amongst the hottest post-AGB stars whose atmospheres are composed of almost pure helium. Thus, their evolution deviates from the hydrogen-deficient post-AGB evolutionary sequence of carbon-dominated stars like e.g. PG 1159 stars. The origin of the O(He) stars is still not explained. They might be either post-early AGB stars or the progeny of R Coronae Borealis stars. We present preliminary results of a non-LTE spectral analysis based on FUSE and HST/COS observations.

We estimate the parameters of the radio surface brightness to diameter (Σ – D) relation for the sample of Galactic planetary nebulae (PNe). The bootstrap re-sampling and orthogonal offsets fitting procedure are applied. The orthogonal fitting procedure provides that the parameter values of D – Σ and Σ – D fits are invariant within the estimated uncertainties. We discuss the probability statistics of the fitted (log Σ = log A - β log D) relation and the resulting fit parameters which is indicative for PN distance determination.

The ESO VLT on Paranal is in transition from first generation instrumentation to second generation, or at least to substantially upgraded instrumentation. The new instrumentation shall establish multipicity gain, high image definition or integral field imaging spectroscopy. Starting from observational highlights, status and trends for groundbased instrumentation will be revisited with emphasis on the field of PNe in all evolutionary phases. This review will concentrate on spectroscopy and scientific cases where groundbased observations offer a particular advantage. To the extent possible, a projection will be given as to the potential of the extremely large telescopes on the horizon, which will work best in the (near-)infrared.