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We present MUSE deep integral-field unit spectroscopy of three planetary nebulae(PNe) with high abundance discrepancy factors (ADF > 20): NGC 6778, M 1-42 and Hf 2-2. We have constructed flux maps for more than 40 emission lines, and use them to build extinction, electron temperature (T$_e$), electron density (n$_e$), and ionic abundances maps of a number of ionic species. The effects of the contribution of recombination to the auroral [N II] and [O II] lines on T$_e$ and the abundance maps of low-ionization species are evaluated using recombination diagnostics. As a result, low T$_e$ values and a downward gradient of T$_e$ are found toward the inner zones of each PN. Spatially, this nearly coincides with the increase of abundances of heavy elements measured using recombination lines in the inner regions of PNe, and strongly supports the presence of two distinct gas phases: a cold and metal-rich and a warm one with "normal" metal content. We have simultaneously constructed, for the first time, the ADF maps of O$^+$ and O$^{2+}$ and found that they centrally peak for all three PNe under study. We show that the main issue when trying to compute realistic abundances from either ORLs or CELs is to estimate the relative contribution of each gas component to the H I emission, and we present a method to evaluate it. It is also found that, for the studied high-ADF PNe, the amount of oxygen in the cold and warm regions is of the same order., 20 pages, 10 Tables, 16 Figures. Additional material in appendix, 1 Table and 22 Figures. This article has been accepted for publication in MNRAS, Published by Oxford University Press on behalf of the Royal Astronomical Society

We report spectrophotometric observations made with SOFIA/FORCAST on 2011 June 2 UT. Optical measurements have previously shown that the abundance discrepancy factor (adf) varies with position in several high-adf PNe, and is highest close to the central star. The very low electron temperature inclusions postulated to explain the abundance discrepancy, must be cooled predominantly by fine structure IR lines. These SOFIA data will map mid-IR FS lines (and our related Herschel program will add several far-IR FS lines) in the bright, well-characterized, high-adf PN NGC 7009. We will compare these IR results with FS optical line measurements in order to correlate ratios of IR to optical fluxes with position, and thus correlate with where the adf peaks.

We present time-resolved optical spectroscopy of V458 Vulpeculae (Nova Vul 2007 No. 1) spread over a period of 15 months starting 301 days after its discovery. Our data reveal radial velocity variations in the HeII {\lambda}5412 and HeII {\lambda}4686 emission lines. A period analysis of the radial velocity curves resulted in a period of 98.09647 \pm 0.00025 min (0.06812255 \pm 0.00000017 d) which we identify with the orbital period of the binary system. V458 Vul is therefore the planetary nebula central binary star with the shortest period known. We explore the possibility of the system being composed of a relatively massive white dwarf (M1 \gsim 1.0 Msun) accreting matter from a post-asymptotic giant branch star which produced the planetary nebula observed. In this scenario, the central binary system therefore underwent two common-envelope episodes. A combination of previous photoionisation modelling of the nebular spectra, post-asymptotic giant branch evolutionary tracks and the orbital period favour a mass of M2 \sim 0.6 Msun for the donor star. Therefore, the total mass of the system may exceed the Chandrasekhar mass, which makes V458 Vul a Type Ia supernova progenitor candidate.

GHαFaS, a new Fabry-Perot system, is now available at the William Herschel Telescope (WHT). It was mounted, for the first time, at the Nasmyth focus of the 4.2-m WHT on La Palma in 2007 July. Using modern technology, with a spectral resolution of the order R ~ 15,000, and with a seeing-limited spatial resolution, GHαFaS will provide a new look at the Hα-emitting gas over a 4.8' circular field in the nearby universe. Many science programs can be done on a 4.2-m class telescope in world-class seeing conditions with a scanning Fabry-Perot. Not only galaxies but H II regions, planetary nebulae, supernova remnants, and the diffuse interstellar medium are subjects for which unique data can be aquired rapidly. Astronomers from the Laboratoire d'Astrophysique Experimentale (LAE) in Montreal, the Laboratoire d'Astrophysique de Marseille (LAM-OAMP), and the Instituto de Astrofisica de Canarias (IAC), have inaugurated GHαFaS by studying in detail the dynamics of some nearby spiral galaxies. A robust set of state-of-the-art tools for reducing and analyzing the data cubes obtained with GHαFaS has also been developed.

We have started a project to search for symbiotic stars using the data from IPHAS, the Hα survey of the Northern Galactic plane. Candidates are selected from the IPHAS photometric catalogue based on their colors, combined with the information in the near-infrared from 2MASS. So far, follow-up spectroscopy allowed us to discover 14 new symbiotic stars, compared to the 10 systems previously known in the IPHAS survey area. Their general characteristics and the most notable cases are briefly presented. the spectroscopic campaign also allowed us to refine the selection criteria for symbiotic stars in IPHAS. Perspectives, which include the extension of the survey in the Southern Galactic plane and a portion of the bulge (VPHAS+), are discussed.

"The now completed INT photometric H-alpha Survey (IPHAS) is a valuable resource to detect planetary nebulae (PNe) in the Northern Galactic Plane. An area of 1800 deg2 of sky has been scanned and hundreds of new PN candidates have been discovered, from the direction of the crowded and dusty Galactic center to the less widely explored Galactic Anticenter area. The final goal is to provide a complete, surface brightness limited census of PNe in the Galactic Plane. We present the survey and some preliminary results on PNe so far identified."

The INT/WFC Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS) is an imaging survey being carried out in H-alpha, r' and i' filters, with the Wide Field Camera (WFC) on the 2.5-metre Isaac Newton Telescope (INT) to a depth of r'=20 (10 sigma). The survey is aimed at revealing large scale structure in our local galaxy, and also the properties of key early and late populations making up the Milky Way. Mapping emission line objects enables a particular focus on objects in the young and old stages of stellar evolution ranging from early T-Tauri stars to late planetary nebulae. In this paper we present the IPHAS Initial Data Release, primarily a photometric catalogue of about 200 million unique objects, coupled with associated image data covering about 1600 square degrees in three passbands. We note how access to the primary data products has been implemented through use of standard virtual observatory publishing interfaces. Simple traditional web access is provided to the main IPHAS photometric catalogue, in addition to a number of common catalogues (such as 2MASS) which are of immediate relevance. Access through the AstroGrid VO Desktop opens up the full range of analysis options, and allows full integration with the wider range of data and services available through the Virtual Observatory. The IDR represents the largest dataset published primarily through VO interfaces to date, and so stands as an examplar of the future of survey data mining. Examples of data access are given, including a cross-matching of IPHAS photometry with sources in the UKIDSS Galactic Plane Survey that validates the existing calibration of the best data., Comment: 17 pages, 23 figures, MNRAS in press. Version with full-resolution figures can be found at http://casu.ast.cam.ac.uk/surveys-projects/iphas

The INT Photometric Halpha Survey of the Northern Galactic Plane (IPHAS) is a 1800 square degrees CCD survey of the northern Milky Way spanning the latitude range -5 < b < +5 (degrees) and reaching down to r' ~ 20 (10-sigma). It may increase the number of known northern emission line sources by an order of magnitude. Representative observations and an assessment of point-source data from IPHAS, now underway, are presented. The data obtained are Wide Field Camera images in Halpha narrow-band, and Sloan r' and i' broad-band, filters. We simulate IPHAS (r' - Halpha, r' - i') point-source colours using a spectrophotometric library of stellar spectra and available filter transmission profiles: this gives expected colours for (i) solar-metallicity stars, without Halpha emission, and (ii) emission line stars. Comparisons with Aquila field observations show that simulated normal star colours reproduce the data well for spectral types earlier than M. Spectroscopic follow-up of a Cepheus field confirms that sources lying above the main stellar locus in the (r' - Halpha, r' - i') plane are emission line objects, with very few failures. Examples of Halpha deficit objects -- a white dwarf and a carbon star -- are shown to be readily distinguished by their IPHAS colours. The role IPHAS can play in studies of nebulae is discussed briefly, and illustrated by a continuum-subtracted mosaic image of the SNR, Shajn 147. The final catalogue of IPHAS point sources will contain photometry on ~80 million objects. (abridged), 25 pages, 20 figures (13 with colour, 12 at reduced resolution). Accepted 23rd June 2005 for publication in MNRAS. A full resolution pdf copy of the paper may be obtained from http://astro.ic.ac.uk/Research/Halpha/North/publications.shtml

The expansion in the plane of the sky of the nebula around the symbiotic nova He2‐147 has been resolved by means of two HST WFPC2 [NII] images taken 3 years apart. The information on the tangential expansion is complemented by the velocities along the line of sight, obtained through VLT integral‐field spectroscopy. This combination of data reveals the global velocity and geometrical pattern of the gas, which is that of a roughly circular knotty ring, inclined on the line of sight, and expanding with a velocity larger than 100 km s−1. Interestingly, the binary nucleus seems to be offset from the centre of expansion of the nebula. Even more remarkable is the fact that, at each nebular position, line profiles are significantly broadened, displaying a range of radial velocities of 150 km s−1 (full width at zero intensity). Several ideas are presented to explain this effect, including the hypothesis of a strong shock front associated with the expanding nova ejecta.

We have measured angular dimensions of 312 planetary nebulae from their images obtained in Halpha (or Halpha + [NII]). We have applied three methods of measurements: direct measurements at the 10% level of the peak surface brightness, Gaussian deconvolution and second-moment deconvolution. The results from the three methods are compared and analysed. We propose a simple deconvolution of the 10% level measurements which significantly improves the reliability of these measurements for compact and partially resolved nebulae. Gaussian deconvolution gives consistent but somewhat underestimated diameters compared to the 10% measurements. Second-moment deconvolution gives results in poor agreement with those from the other two methods, especially for poorly resolved nebulae. From the results of measurements and using the conclusions of our analysis we derive the final nebular diameters which should be free from systematic differences between small (partially resolved) and extended (well resolved) objects in our sample., Comment: 10 figures, 2 tables

Some planetary nebulae (PNe) show microstructures of low ionization located in their outer regions, i.e. external to the bright rim defined by the fast vs. slow wind interaction region. Morphological and kinematic analysis of some of these PNe show low ionization knots which clearly share the expansion of the outer shell of the host nebulae (e.g. IC 2553). Sometimes, these knots possess an accentuated degree of symmetry. Given that in situ instabilities are not thought to form symmetrical features, we explore the idea that these symmetric pairs of knots are fossil condensations of the AGB wind being modified by interaction with the expanding ionization front. This very appealing possibility would imply that the mass loss of the pre-PN stages has episodes of highly collimated and symmetric ejections. In other PNe knots of low ionization in the outer shells are not symmetric (e.g. NGC 5882) and could be formed by either simple in situ instabilities and/or fossil condensations.

The conventional interpretation of the “Wilson effect”is based on the fact that, in a simple photoionization model of a thick shell in free expansion, the elements with a high ionization potential are found in the innermost part of the shell, which move slower than the outer regions where the low ionization ions are located. A real PN is however a much more complex object than in the picture above. For these reasons, we are carrying on a project aimed at studying in detail the Wilson effect in a large number of objects of different types.We present here preliminary results for two PNe, the bipolar nebula Hu 1–2 and the elliptical NGC 7662. Observation have been secured with the Utrecht Echelle Spectro-graph placed at 4.2m William Herschel Telescope, (La Palma, Canary Islands). The spatial resolution is 0.36 arcsec, and the resolving power R=46000. The results are presented in Table 1. The increase of expansion velocity with decreasing potential is clearly seen except for Hydrogen. This ion is a quite peculiar case: although its ionization potential is quite low, this element behaves also as a high excitation atom since it has only one possible ionized state. Futhermore, as we have spatial resolution we can study this relation between velocity and ionization potential in different points of the nebula.

A large set of narrow-band images of planetary nebulae (PNe) have been studied together with the location of their nuclei (PNNi) on the logT eff — logL/L ⊙ plane, in order to disclose possible correlations between the morphological class of the PNe and the evolutionary stage of their PNNi.

Bipolar symmetry characterizes the morphology of a large number of objects thought to be protoplahetary nebulae. Among these, NGC 6537 and Hb 5 were observed on July 1991 at the 3.5m NTT telescope of the European Southern Observatory, using the EMMI multimode instrument. Hα+[NII] images (Fig. 1) allowed accurate information on the faintest structure of the external region of these nebulae: the line emission extends out to 120″ from the center of NGC 6537 and out to 30″ in Hb 5 (compared to the nebular radii of 40″ and 10″, respectively, quoted in the literature). An interesting feature of the morphology of both nebulae is the point-symmetrical distribution of line emission characterizing their brightest regions.

Scanning Perot-Fabry observations (data-cubes of contiguous sub-angstrom monochromatic images) allow us to isolate line-emission from nearby continuum using a ‘local’ very narrow-band filter, without being troubled by the velocity blurring due to internal kinematics.

The Seyfert 1 galaxy NGC 3783 was intensely monitored between 1991 December and 1992 August. We present the results from the ground-based observations in the optical and near-IR, which complement the data-set from the IUE, discussed elsewhere. Spectroscopic and photometric data from many observatories were combined in order to obtain well sampled light curves of the continuum and of H-Beta. During the campaign the source varied significantly. The light curves of the optical continuum and of H-Beta are similar to those obtained with the IUE. The near-IR flux did not vary significantly except for an increase at the end of the campaign. The optical continuum and the flux of H-Beta lag the UV continuum by 1 day or less and by 8 days respectively. These results confirm that the continuum variations are simultaneous or have a very small lag across the entire UV-optical range, and that the lines of NGC 3783 respond to ionizing continuum variations with less delay than those of NGC 5548. As in NGC 5548, the lag of H-Beta is greater than those of the high ionization lines.

Observations taken at Calar Alto and Loiano led to the possible identification of the GRB 971227 optical counterpart. Details on the observations are presented.