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M105 is an early-type galaxy in the nearby Leo I group, the closest galaxy group to contain all galaxy types and therefore an excellent environment to explore the low-mass end of intra-group light (IGL) assembly. We present a new extended kinematic survey of planetary nebulae (PNe) in M105 and the surrounding 30'x30' in the Leo I group with the Planetary Nebula Spectrograph. We use PNe as kinematic tracers of the diffuse stellar light in the halo and IGL and employ Gaussian mixture models to separate contributions from the companion galaxy NGC 3384 and associate PNe with halo and IGL components around M105. We present a catalogue of 314 PNe and firmly associate 93 with NGC 3384 and 169 with M105. The PNe in M105 are further associated with its halo and the surrounding exponential envelope. We construct smooth velocity and velocity dispersion fields and calculate projected rotation, velocity dispersion, and $\lambda_R$ profiles for each component. Halo PNe exhibit declining velocity dispersion and rotation profiles, while the velocity dispersion and rotation of the exponential envelope increase notably at large radii. We identify three regimes with distinct kinematics that are linked to distinct stellar population properties: (i) the rotating core (within $1~R_\mathrm{eff}$) formed in situ and dominated by metal-rich ([M/H]~0) stars likely formed in situ, (ii) the halo from 1 to $7.5~R_\mathrm{eff}$ consisting of intermediate-metallicity stars ([M/H]>-1), either formed in situ or brought in through major mergers, and (iii) the exponential envelope reaching beyond our farthest data point at 16 $R_\mathrm{eff}$, predominately composed of metal-poor ([M/H], Comment: Submitted to A&A, comments welcome. 20 pages, 14 figures, abstract abridged

We investigate the kinematic properties of nine nearby early-type galaxies with evidence of a disc-like component. Three of these galaxies are located in the field, five in the group, and only one in the cluster environment. By combining the kinematics of the stars with those of the globular clusters (GCs) and planetary nebulae (PNe), we probe the outer regions of our galaxies out to $\sim 4\!-\!6\, R_{\mathrm{e}}$. Six galaxies have PNe and red GCs that show good kinematic alignment with the stars, whose rotation occurs along the photometric major-axis of the galaxies, suggesting that both the PNe and red GCs are good tracers of the underlying stellar population beyond that traced by the stars. Additionally, the blue GCs also show rotation that is overall consistent with that of the red GCs in these six galaxies. The remaining three galaxies show kinematic twists and misalignment of the PNe and GCs with respect to the underlying stars, suggesting recent galaxy interactions. From the comparison with simulations, we propose that all six aligned galaxies that show similar dispersion-dominated kinematics at large radii ($\gt 2\!-\!3\, R_{\mathrm{e}}$) had similar late (z ≲ 1) assembly histories characterized by mini mergers (mass-ratio < 1:10). The different Vrot/σ profiles are then the result of an early (z > 1) minor merger (1:10 < mass-ratio < 1:4) for the four galaxies with peaked and decreasing Vrot/σ profiles and of a late minor merger for the two galaxies with flat Vrot/σ profiles. The three misaligned galaxies likely formed through multiple late minor mergers that enhanced their velocity dispersion at all radii, or a late major merger that spun-up both the GC subpopulations at large radii. Therefore, lenticular galaxies can have complex merger histories that shape their characteristic kinematic profile shapes., DF, WC, KB, and AD acknowledge support from the Australian Research Council under Discovery Project 170102344. AFM has received financial support through the Postdoctoral Junior Leader Fellowship Programme from “la Caixa” Foundation(LCF/BQ/LI18/11630007). AJR was supported by National Science Foundation grant AST-1616710 and by a Research Corporation for Science Advancement Cottrell Scholar.

A copy of the reduced spectra is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/649/A164. Currently at Centro de Astrobiología (CSIC-INTA), Torreján de Ardoz, Madrid, Spain. Context. Fast outflows and their interaction with slow shells (generally known as the fossil circumstellar envelope of asymptotic giant branch stars) play an important role in the structure and kinematics of protoplanetary and planetary nebulae (pPNe, PNe). To properly study their effects within these objects, we also need to observe the intermediate-temperature gas, which is only detectable in the far-infrared and submillimetre (submm) transitions. Aims. We study the physical conditions of the outflows presented in a number of pPNe and PNe, with a focus on their temperature and excitation states. Methods. We carried out Herschel/HIFI observations in the submm lines of 12CO in nine pPNe and nine PNe and complemented them with low-J CO spectra obtained with the IRAM 30m telescope and taken from the literature. The spectral resolution of HIFI allows us to identify and measure the different nebular components in the line profiles. The comparison with large velocity gradient model predictions was used to estimate the physical conditions of the warm gas in the nebulae, such as excitation conditions, temperature, and density. Results. We found high kinetic temperatures for the fast winds of pPNe, typically reaching between 75 K and 200 K. In contrast, the high-velocity gas in the sampled PNe is colder, with characteristic temperatures between 25 K and 75 K, and it is found in a lower excitation state. We interpret this correlation of the kinetic temperature and excitation state of fast outflows with the amount of time elapsed since their acceleration (probably driven by shocks) as a consequence of the cooling that occurred during the pPN phase. We thank the anonymous referee for their useful and constructive comments on the paper. We also thank Prof. Hans Olofsson for his thorough review of this manuscript. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the USA under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands, and with major contributions from Germany, France and the USA. Consortium members are: Canada: CSA, U.Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland: NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri-INAF; The Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronomico Nacional (IGN), Centro de Astrobiologia (CSICINTA); Sweden: Chalmers University of Technology -MC2, RSS and GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University -Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. This paper is based on obser-vations carried out at the IRAM-30m single-dish telescope. IRAM is sup-ported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). JA and VB are partly funded by the Spanish MICIIN grant AYA2016-78994-P Peerreview

We present the analysis of the planetary nebula (PN) NGC 2371 around the [Wolf-Rayet] (WR) star WD 0722+295. Our Isaac Newton Telescope intermediate dispersion spectrograph spectra, in conjunction with archival optical and ultraviolet images, unveil in unprecedented detail the high ionization of NGC 2371. The nebula has an apparent multipolar morphology, with two pairs of lobes protruding from a barrel-like central cavity, a pair of dense low ionization knots misaligned with the symmetry axis embedded within the central cavity, and a high-excitation halo mainly detected in He ii. The abundances from the barrel-like central cavity and dense knots agree with abundance determinations for other PNe with [WR]-type central stars of PNe. We suggest that the densest knots inside NGC 2371 are the oldest structures, remnant of a dense equatorial structure, while the main nebular shell and outer lobes resulted from a latter ejection that ended the stellar evolution. The analysis of position-velocity diagrams produced from our high-quality spectra suggests that NGC 2371 has a bipolar shape with each lobe presenting a double structure protruding from a barrel-like central region. The analysis of the spectra of WD 0722+295 results in similar stellar parameters as previously reported. We corroborate that the spectral subtype corresponds with a [WO1] type. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society., VMAGG, JAT, MAG, and HT are funded by Dirección General de Asuntos del Personal Académico (DGAPA), Universidad Nacional Autónoma de México (UNAM) PAPIIT project IA100318. GRL acknowledges support from Fundación Marcos Moshinsky, Consejo Nacional de Ciencia y Tecnología (CONACYT), and Programa para el Desarrollo Profe-sional Docente (PRODEP) (Mexico). MAG acknowledges support of the Spanish Ministerio de Ciencia, Innovación y Universidades grant PGC2018-102184-B-I00, cofunded by FEDER funds. LS thanks support from UNAM PAPIIT grant IN101819. YDM thanks CONACYT for the research grant CB-A1-S-25070. This work has make extensive use of the NASA’s Astrophysics Data System. This paper also presents data obtained with the MOS camera at the Canada–France–Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. The authors thank E. Santamaría for helping produce the velocity sketch of NGC 2371. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Extragalactic planetary nebulae (PNe) are detectable through relatively strong nebulous [OIII] emission and act as direct probes into the local stellar population. Because they have an apparently universal invariant magnitude cut-off, PNe are also considered to be a remarkable standard candle for distance estimation. Through detecting PNe within the galaxies, we aim to connect the relative abundances of PNe to the properties of their host galaxy stellar population. By removing the stellar background components from FCC 167 and FCC 219, we aim to produce PN luminosity functions (PNLF) of these galaxies, and thereby also estimate the distance modulus to these two systems. Finally, we test the reliability and robustness of our novel detection and analysis method. It detects unresolved point sources by their [OIII] 5007{\AA} emission within regions that have previously been unexplored. We model the [OIII] emissions in the spatial and spectral dimensions together, as afforded to us by the Multi Unit Spectroscopic Explorer (MUSE), and we draw on data gathered as part of the Fornax3D survey. For each source, we inspect the properties of the nebular emission lines to remove other sources that might hinder the safe construction of the PNLF, such as supernova remnants and HII regions. As a further step, we characterise any potential limitations and draw conclusions about the reliability of our modelling approach through a set of simulations. By applying this novel detection and modelling approach to integral field unit observations, we report for the distance estimates and luminosity-specific PNe frequency values for the two galaxies. Furthermore, we include an overview of source contamination, galaxy differences, and possible effects on the PNe populations in the dense stellar environments., Comment: 16 pages, 17 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics Journal. Replaced with published version

A significant fraction of planetary nebulae (PNe) exhibit collimated outflows, distinct narrow kinematical components with notable velocity shifts with respect to the main nebular shells typically associated with low-ionization compact knots and linear or precessing jet-like features. We present here a spatio-kinematical investigation of a sample of 12 PNe with morphologies in emission lines of low-ionization species suggestive of collimated outflows. Using archival narrow-band images and our own high-dispersion long-slit echelle spectra, we confirm the presence of collimated outflows in Hen 2-429, J 320, M 1-66, M 2-40, M 3-1, and NGC 6210 and possibly in NGC 6741, for which the spatio-kinematical data can also be interpreted as a pair of bipolar lobes. The presence of collimated outflows is rejected in Hen 2-47, Hen 2-115, M 1-26, and M 1-37, but their morphology and kinematics are indicative of the action of supersonic outflows that have not been able to pierce through the nebular envelope. In this sense, M 1-66 appears to have experienced a similar interaction between the outflow and nebular envelope, but, as opposed to these four PNe, the outflow has been able to break through the nebular envelope. It is suggested that the PNe without collimated outflows in our sample are younger or descend from lower mass progenitors than those that exhibit unambiguous collimated outflows. © 2019 The Author(s), JSR-G and MAG acknowledge support of the grants AYA 2014-57280-P and PGC2018-102184-B-I00, co-funded with FEDER funds. SDP acknowledges financial support from the Spanish Ministerio de Econom?a y Competitividad under grants AYA2013 47742-C4-1-P and AYA2016 79724-C4-4-P, from Junta de Andaluc?a Excellence Project PEX2011 FQM-7058. JAT and MAG are also funded by UNAM DGAPA PAPIIT project IA100318. LFM acknowledges partial support by grant AYA2017-84390-C2-R, co-funded with FEDER funds. JSR-G, MAG, LFM, and SDP acknowledge financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award for the Instituto de Astrof?sica de Andaluc?a (SEV-2017-0709). We thank Dr. Laurence Sabin for a thorough reading of the manuscript and her valuable comments that helped us to improve it. Based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (STECF/ ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA). This research has made also use of the NASA's Astrophysics Data System. This research made use of PYTHON (http://www.python.o rg) and IPYTHON (P?rez, & Granger 2007), APLpy (Robitaille, & Bressert 2012), Numpy (Van Der Walt, Colbert & Varoquaux 2011), Pandas (McKinney 2010), and Matplotlib (Hunter 2007), a suite of open-source PYTHON modules that provides a framework for creating scientific plots. This research made use of Astropy, a community-developed core PYTHON package for Astronomy (Astropy Collaboration et al. 2013). The Astropy web site is http://www.astropy.org.

The orbital period distribution of close binary stars consisting of a white dwarf and a main-sequence star (WDMS) is a powerful observational constraint on population synthesis models of the poorly understood common-envelope (CE) interaction. Models have often struggled to reproduce the small number of post-CE WDMS binaries with anomalously long orbital periods greater than $\sim$4 d, though recent studies suggest that in longer period systems recombination energy may help contribute to the efficient ejection of the CE. Planetary nebulae (PNe) are an emerging source of rare long period post-CE binaries which can act as powerful complementary constraints on population synthesis models to more traditional post-CE binary populations. A tentative 9.0 d orbital period was recently proposed for the central star of the PN IC~4776, potentially one of the longest periods observed in post-CE WDMS binaries. Here we present SALT HRS observations of IC~4776 that rule out a 9.0 d orbital period, as well as the previously suggested Wolf-Rayet classification of the primary. The SALT HRS data establish a 3.11 d orbital period and rule out Of and Wolf-Rayet primary spectral types. Assuming a mass of 0.6 $M_\odot$ for the primary and an orbital inclination matching the nebula orientation, we find a companion mass of $0.22\pm0.03$ $M_\odot$, most likely corresponding to an M4V companion. The orbital period of IC~4776 is still consistent with findings of abundance discrepancy factor (ADF) studies of post-CE PNe, but any trends in the ADF distribution derived from the sample remain significantly biased by selection effects., 7 pages, 5 figures, 3 tables. Accepted for publication in MNRAS

22 pags.; 17 figs., 3 tabs., 3 apps., Young massive stars regulate the physical conditions, ionization, and fate of their natal molecular cloud and surroundings. It is important to find tracers that quantify the stellar feedback processes that take place on different spatial scales. We present -85 arcmin velocity-resolved maps of several submillimeter molecular lines, taken with Herschel/HIFI, toward the closest high-mass star-forming region, the Orion molecular cloud 1 core (OMC-1). The observed rotational lines include probes of warm and dense molecular gas that are difficult, if not impossible, to detect from ground-based telescopes: CH (J = 1-0), CO (J = 10-9), HCO (J = 6-5), HCN (J = 6-5), and CH (N, J = 1, 3/2-1, 1/2). These lines trace an extended but thin layer (AV ≃ 3-6 mag or ~10 cm) of molecular gas at high thermal pressure, P = nH · Tk ≈ 107-109 cm K, associated with the far-ultraviolet (FUV) irradiated surface of OMC-1. The intense FUV radiation field - emerging from massive stars in the Trapezium cluster - heats, compresses, and photoevaporates the cloud edge. It also triggers the formation of specific reactive molecules such as CH+. We find that the CH (J = 1-0) emission spatially correlates with the flux of FUV photons impinging the cloud: G0 from ~10 to ~10. This relationship is supported by constant-pressure photodissociation region (PDR) models in the parameter space P=G ≈ [5 × 10 - 8 × 10] cm K where many observed PDRs seem to lie. The CH+ (J = 1-0) emission also correlates with the extended infrared emission from vibrationally excited H (v ≫ 1), and with that of [C II] 158 μm and CO J = 10-9, all emerging from FUV-irradiated gas. These spatial correlations link the presence of CH+ to the availability of C+ ions and of FUV-pumped H2 (v ≫ 1) molecules.We conclude that the parsec-scale CH emission and narrow-line (δ ≃ 3 km s) mid-J CO emission arises from extended PDR gas and not from fast shocks. PDR line tracers are the smoking g of the stellar feedback from young massive stars. The PDR cloud surface component in OMC-1, with a mass density of 120-240 M⊙pc, represents ~5-10% of the total gas mass; however, it dominates the emitted line luminosity, the average CO J = 10-9 surface luminosity in the mapped region being ~35 times brighter than that of CO J = 2-1. These results provide insights into the source of submillimeter CH+ and mid-J CO emission from distant star-forming galaxies., We thank the Spanish MICIU for funding support under grants AYA2016-75066-C2-1-P and AYA2017-85111-P, and the ERC for support under grant ERC-2013-Syg-610256-NANOCOSMOS.

Context. There are more than 3000 known Galactic planetary nebulae (PNe), but only 492 central stars of Galactic planetary nebulae (CSPN) have known spectral types. It is vital to increase this number in order to have reliable statistics, which will lead to an increase of our understanding of these amazing objects. Aims. We aim to contribute to the knowledge of central stars of planetary nebulae and stellar evolution. Methods. This observational study is based on Gemini Multi-Object Spectrographs (GMOS) and with the Intermediate Dispersion Spectrograph (IDS) at the Isaac Newton Telescope (INT) spectra of 78 CSPN. The objects were selected because they did not have any previous classification, or the present classification is ambiguous. These new high quality spectra allowed us to identify the key stellar lines for determining spectral classification in the Morgan-Keenan (MK) system. Results. We have acquired optical spectra of a large sample of CSPN. From the observed targets, 50 are classified here for the first time while for 28 the existing classifications have been improved. In seven objects we have identified a P-Cygni profile at the He i lines. Six of these CSPN are late O-type. The vast majority of the stars in the sample exhibit an absorption-type spectrum, and in one case we have found wide emission lines typical of [WR] stars. We give a complementary, and preliminary, classification criterion to obtain the sub-type of the O(H)-type CSPN. Finally, we give a more realistic value of the proportion of CSPN that are rich or poor in hydrogen., Accepted to be published in the A&A

Accepted for publication in The Astrophysical Journal (ApJ) © 2018. The American Astronomical Society.-- 33 pages including 20 figures and 9 tables, We report deep spectroscopy of 10 planetary nebulae (PNe) in the Andromeda Galaxy (M31) using the 10.4 m Gran Telescopio Canarias (GTC). Our targets reside in different regions of M31, including halo streams and the dwarf satellite M32, and kinematically deviate from the extended disk. The temperature-sensitive [O iii] λ4363 line is observed in all PNe. For four PNe, the GTC spectra extend beyond 1 μm, enabling the explicit detection of the [S iii] λ6312 and λλ9069, 9531 lines and thus determination of the [S iii] temperature. Abundance ratios are derived and generally consistent with AGB model predictions. Our PNe probably all evolved from low-mass (, We are grateful to the anonymous referee whose excellent comments and suggestions greatly improved this article. This work is supported by grants from the HKRGC (HKU7062/13P) and the Seed Fund for Basic Research at the HKU (201611159037). This work is partly supported by grants DGAPA/PAPIIT-107215 and CONACyT-CB2015-254132. R.G.B. acknowledges support from the Spanish Ministerio de Economia y Competitividad, through projects AYA2016-77846-P and AYA2014-57490-P. X.W.L. acknowledges financial support from the National Key Basic Research Program of China 2014CB845700. M3.B. is partially supported by ANPCyT through grant PICT-2014-2708 and by MinCyT-DAAD bilateral cooperation through grant DA/16/07. X.F. is grateful to Albert A. Zijlstra, Bruce Balick, and Romano L.M. Corradi for in-depth discussion. We thank Paolo Ventura for providing us the AGB model predictions. We also thank Michael R. Merrifield for giving us the permission to reproduce the stellar orbit (in Figure 2 of this paper) based on Figure 2 in Merrett et al. (2003). This research also made use of NASA's Astrophysics Data System (http://adsabs.harvard.edu), the SDSS DR10 Science Archive Server (SAS; http://data.sdss3.org/), the SDSS DR12 Finding Chart Tool (https://skyserver.sdss.org/dr12/en/tools/chart/), and the SIMBAD Astronomical Database (http://simbad.u-strasbg.fr/simbad/).

The primary goal of this paper is to make a direct comparison between the measured and model-predicted abundances of He, C, and N in a sample of 35 well-observed Galactic planetary nebulae (PNe). All observations, data reductions, and abundance determinations were performed in house to ensure maximum homogeneity. Progenitor star masses (M ≤ 4M⊙) were inferred using two published sets of post-asymptotic giant branch model tracks and L and Teff values. We conclude the following: (1) the mean values of N/O across the progenitor mass range exceeds the solar value, indicating significant N enrichment in the majority of our objects; (2) the onset of hot bottom burning appears to begin around 2 M⊙, i.e. lower than ~5M⊙ implied by theory; (3) most of our objects show a clear He enrichment, as expected from dredge-up episodes; (4) the average sample C/O value is 1.23, consistent with the effects of third dredge up; and (5) model grids used to compare to observations successfully span the distribution over metallicity space of all C/O and many He/H data points but mostly fail to do so in the case of N/O. The evident enrichment of N in PN and the general discrepancy between the observed and model-predicted N/O abundance ratios signal the need for extra mixing as an effect of rotation and/or thermohaline mixing in the models. The unexpectedly high N enrichment that is implied here for low-mass stars, if confirmed, will likely impact our conclusions about the source of N in the Universe., Instituto de Astrofísica de La Plata, Facultad de Ciencias Astronómicas y Geofísicas

Recent state-of-the-art calculations of A-values and electron impact excitation rates for Fe III are used in conjunction with the Cloudy modeling code to derive emission line intensity ratios for optical transitions among the fine-structure levels of the 3d$^6$ configuration. A comparison of these with high resolution, high signal-to-noise spectra of gaseous nebulae reveals that previous discrepancies found between theory and observation are not fully resolved by the latest atomic data. Blending is ruled out as a likely cause of the discrepancies, because temperature- and density-independent ratios (arising from lines with common upper levels) match well with those predicted by theory. For a typical nebular plasma with electron temperature $T_{\rm e} = 9000$ K and electron density $\rm N_{e}=10^4 \, cm^{-3}$, cascading of electrons from the levels $\rm ^3G_5$, $\rm ^3G_4$ and $\rm ^3G_3$ plays an important role in determining the populations of lower levels, such as $\rm ^3F_4$, which provide the density diagnostic emission lines of Fe III, such as $\rm ^5D_4$ - $\rm ^3F_4$ at 4658 \AA. Hence further work on the A-values for these transitions is recommended, ideally including measurements if possible. However, some Fe III ratios do provide reliable $N_{\rm e}$-diagnostics, such as 4986/4658. The Fe III cooling function calculated with Cloudy using the most recent atomic data is found to be significantly greater at $T_e$ $\simeq$ 30000 K than predicted with the existing Cloudy model. This is due to the presence of additional emission lines with the new data, particularly in the 1000--4000 \AA\ wavelength region., Comment: Accepted for publication in the ApJ

[Context] The mechanism behind the shaping of bipolar planetary nebulae is still poorly understood. It is becoming increasingly clear that the main agents must operate at their innermost regions, where a significant equatorial density enhancement should be present and related to the collimation of light and jet launching from the central star preferentially towards the polar directions. Most of the material in this equatorial condensation must be lost during the asymptotic giant branch as stellar wind and later released from the surface of dust grains to the gas phase in molecular form. Accurately tracing the molecule-rich regions of these objects can give valuable insight into the ejection mechanisms themselves., [Aims] We investigate the physical conditions, structure and velocity field of the dense molecular region of the planetary nebula NGC 6302 by means of ALMA band 7 interferometric maps., [Methods] The high spatial resolution of the CO and CO J = 3-2 ALMA data allows for an analysis of the geometry of the ejecta in unprecedented detail. We built a spatio-kinematical model of the molecular region with the software SHAPE and performed detailed non-LTE calculations of excitation and radiative transfer with the shapemol plug-in., [Results] We find that the molecular region consists of a massive ring out of which a system of fragments of lobe walls emerge and enclose the base of the lobes visible in the optical. The general properties of this region are in agreement with previous works, although the much greater spatial resolution of the data allows for a very detailed description. We confirm that the mass of the molecular region is 0.1 M. Additionally, we report a previously undetected component at the nebular equator, an inner, younger ring inclined ~60° with respect to the main ring, showing a characteristic radius of 7.5 × 10 cm, a mass of 2.7 × 10M, and a counterpart in optical images of the nebula. This inner ring has the same kinematical age as the northwest optical lobes, implying it was ejected approximately at the same time, hundreds of years after the ejection of the bulk of the molecular ring-like region. We discuss a sequence of events leading to the formation of the molecular and optical nebulae, and briefly speculate on the origin of this intriguing inner ring., This work was partially supported by the Spanish MINECO within the programme “Físico-química del medio interestelar y circunestelar en la era de ALMA” (AYA2012-32032), and by the European Research Council (ERC Grant 610256: NANOCOSMOS).

The post-asymptotic giant branch (AGB) phase is arguably one of the least understood phases of the evolution of low- and intermediate- mass stars. The recent post-AGB evolutionary sequences computed by Miller Bertolami (2016) are at least three to ten times faster than those previously published by Vassiliadis & Wood (1994) and Bloecker (1995) which have been used in a large number of studies. This is true for the whole mass and metallicity range. The new models are also $\sim$0.1-0.3 dex brighter than the previous models with similar remnant masses. In this short article we comment on the main reasons behind these differences, and discuss possible implications for other studies of post-AGB stars or planetary nebulae., 4 pages, 3 figures, to appear in Proceedings of IAU Symposium 323 (Planetary Nebulae: Multi-Wavelength Probes of Stellar and Galactic Evolution), eds. Xiaowei Liu, Letizia Stanghellini, & Amanda Karakas

Planetary nebulae form in stellar populations with ages from 1 to 10 Gyr, and can be used to trace their star formation histories. Here we apply this to the Galactic bulge, where there are indications both for an old origin and for younger stars. We use new stellar models, which have significant different evolutionary speeds during the post-AGB phase. We apply these new models to a sample of 32 planetary nebulae with HST imaging and VLT spectroscopy. The results show evidence for an old starburst, followed by continuous star formation until at least 2Gyr ago. This agrees very well with recent analysis of colour-magnitude diagrams of the bulge. We show that the new models can also explain the [OIII] luminosity functions, and predict the uniform luminosity cut-off both in spiral galaxies and old elliptical galaxies., Facultad de Ciencias Astronómicas y Geofísicas

Context. At least 492 central stars of Galactic planetary nebulae (CSPNs) have been assigned spectral types. Since many CSPNs are faint, these classification efforts are frequently made at low spectral resolution. However, the stellar Balmer absorption lines are contaminated with nebular emission; therefore in many cases a low-resolution spectrum does not enable the determination of the H abundance in the CSPN photosphere. Whether or not the photosphere is H deficient is arguably the most important fact we should expect to extract from the CSPN spectrum, and should be the basis for an adequate spectral classification system. Aims. Our purpose is to provide accurate spectral classifications and contribute to the knowledge of central stars of planetary nebulae and stellar evolution. Methods. We have obtained and studied higher quality spectra of CSPNs described in the literature as weak emission-line star (WELS). We provide descriptions of 19 CSPN spectra. These stars had been previously classified at low spectral resolution. We used medium-resolution spectra taken with the Gemini Multi-Object Spectrograph (GMOS). We provide spectral types in the Morgan-Keenan (MK) system whenever possible. Results. Twelve stars in our sample appear to have normal H rich photospheric abundances, and five stars remain unclassified. The rest (two) are most probably H deficient. Of all central stars described by other authors as WELS, we find that at least 26% of them are, in fact, H rich O stars, and at least 3% are H deficient. This supports the suggestion that the denomination WELS should not be taken as a spectral type, because, as a WELS is based on low-resolution spectra, it cannot provide enough information about the photospheric H abundance., Facultad de Ciencias Astronómicas y Geofísicas, Instituto de Astrofísica de La Plata

L.C. thanks the Spanish MICINN for funding support through grants AYA2009-07304 and CSD2009-00038, Arnaud, M., Atrio-Barandela, F., Aumont, J., Baccigalupi, C., Banday, A.J., Barreiro, R.B., Battaner, E., Benabed, K., Benoit-Lévy, A., Bernard, J.-P., Bersanelli, M., Bielewicz, P., Bonaldi, A., Bond, J.R., Borrill, J., Bouchet, F.R., Buemi, C.S., Burigana, C., Cardoso, J.-F., Casassus, S., Catalano, A., Cerrigone, L., Chamballu, A., Chiang, H.C., Colombi, S., Colombo, L.P.L., Couchot, F., Crill, B.P., Curto, A., Cuttaia, F., Davies, R.D., Davis, R.J., De Bernardis, P., De Rosa, A., De Zotti, G., Delabrouille, J., Dickinson, C., Diego, J.M., Donzelli, S., Doré, O., Dupac, X., Enßlin, T.A., Eriksen, H.K., Finelli, F., Frailis, M., Franceschi, E., Galeotta, S., Ganga, K., Giard, M., González-Nuevo, J., Górski, K.M., Gregorio, A., Gruppuso, A., Hansen, F.K., Harrison, D.L., Hildebrandt, S.R., Hivon, E., Holmes, W.A., Hora, J.L., Hornstrup, A., Hovest, W., Huffenberger, K.M., Jaffe, T.R., Jones, W.C., Juvela, M., Keihänen, E., Keskitalo, R., Kisner, T.S., Knoche, J., Kunz, M., Kurki-Suonio, H., Lähteenmäki, A., Lamarre, J.-M., Lasenby, A., Lawrence, C.R., Leonardi, R., Leto, P., Lilje, P.B., Linden-Vørnle, M., López-Caniego, M., Macías-Pérez, J.F., Maffei, B., Maino, D., Mandolesi, N., Martin, P.G., Masi, S., Massardi, M., Matarrese, S., Mazzotta, P., Mendes, L., Mennella, A., Migliaccio, M., Miville-Deschênes, M.-A., Moneti, A., Montier, L., Morgante, G., Mortlock, D., Munshi, D., Murphy, J.A., Naselsky, P., Nati, F., Natoli, P., Noviello, F., Novikov, D., Novikov, I., Pagano, L., Pajot, F., Paladini, R., Paoletti, D., Peel, M., Perdereau, O., Perrotta, F., Piacentini, F., Piat, M., Pietrobon, D., Plaszczynski, S., Pointecouteau, E., Polenta, G., Popa, L., Pratt, G.W., Procopio, P., Prunet, S., Puget, J.-L., Rachen, J.P., Reinecke, M., Remazeilles, M., Ricciardi, S., Riller, T., Ristorcelli, I., Rocha, G., Rosset, C., Roudier, G., Rubiño-Martín, J.A., Rusholme, B., Sandri, M., Savini, G., Scott, D., Spencer, L.D., Stolyarov, V., Sutton, D., Suur-Uski, A.-S., Sygnet, J.-F., Tauber, J.A., Terenzi, L., Toffolatti, L., Tomasi, M., Trigilio, C., Tristram, M., Trombetti, T., Tucci, M., Umana, G., Valiviita, J., Van Tent, B., Vielva, P., Villa, F., Wade, L.A., Wandelt, B.D., Zacchei, A., Zijlstra, A., Zonca, A.

DFG thanks the European Research Council (ADG-2011 ECOGAL), and Brazilian agencies CNPq (no. 300382/2008-1), CAPES (3400-13-1) and FAPESP (no.2011/12909-8) for financial support. HM thanks CNPq grant 573648/2008-5 and FAPEMIG grants APQ-02030-10 and CEX-PPM-00235-12. For the past decade, observations of the alignment of planetary nebulae (PNe) symmetries with respect to the Galactic disc have led to conflicting results. Recently, the first direct observational evidence for a real alignment between PNe and local interstellar magnetic fields in the central part of the Galaxy (b 100 μG are required in order to be dynamically dominant. This is found to occur only at later evolutionary stages, therefore, being unable to change the general morphology of the nebula. However, the symmetry axis of bipolar and elliptical nebulae end up aligned to the external field. This result can explain why different samples of PNe result in different conclusions regarding the alignment of PNe. Objects located at high Galactic latitudes, or at large radii, should present no preferential alignment with respect to the Galactic plane. PNe located at the Galactic centre and low latitudes would, on the other hand, be preferentially aligned to the disc. Finally, we present synthetic polarization maps of the nebulae to show that the polarization vectors, as well as the field lines at the expanding shell, are not uniform even in the strongly magnetized case, indicating that polarization maps of nebulae are not adequate in probing the orientation, or intensity, of the dominant external field. Publisher PDF

Fundamental parameters characterizing the end-state of intermediate-mass stars may be constrained by discovering planetary nebulae (PNe) in open clusters (OCs). Cluster membership may be exploited to establish the distance, luminosity, age, and physical size for PNe, and the intrinsic luminosity and mass of its central star. Four potential PN-OC associations were investigated, to assess the cluster membership for the PNe. Radial velocities were measured from intermediate-resolution optical spectra, complemented with previous estimates in the literature. When the radial velocity study supported the PN/OC association, we analyzed if other parameters (e.g., age, distance, reddening, central star brightness) were consistent with this conclusion. Our measurements imply that the PNe VBe3 and HeFa1 are not members of the OCs NGC5999 and NGC6067, respectively, and likely belong to the background bulge population. Conversely, consistent radial velocities indicate that NGC2452/NGC2453 could be associated, but our results are not conclusive and additional observations are warranted. Finally, we demonstrate that all the available information point to He2-86 being a young, highly internally obscured PN member of NGC4463. New near-infrared photometry acquired via the Vista Variables in the Via Lactea ESO public survey was used in tandem with existing UBV photometry to measure the distance, reddening, and age of NGC4463, finding d=1.55+-0.10 kpc, E(B-V)=0.41+-0.02, and tau=65+-10 Myr, respectively. The same values should be adopted for the PN if the proposed cluster membership will be confirmed., Accepted for publication in A&A

Context. Planetary nebulae (PNe) are powerful tracers of evolved stellar populations. Among the 3000 known PNe in the Galaxy, about 600 are located within the 520 square-degree area covered by the VVV survey. The VVV photometric catalogue provides an important new dataset for the study of PNe, with high-resolution imaging in five near-infrared bands. Aims. There are various colour-colour diagrams that can be obtained from the VVV filters. We investigate the location of PNe in these diagrams and the separation from other types of objects. This includes the new Y-J vs. Z-Y diagram. Methods. Aperture photometry of known PNe in the VVV area was retrieved from source catalogues. Care was taken to minimise any confusion with field stars. The colours of the PNe we are determined for (H-Ks), (J-H), (Z-Y), and (Y-J), and compared to stars and to other types of emission line objects. Cloudy photo-ionisation models were used to predict colours for typical PNe. Results. We present near-infrared photometry for 353 known PNe. The best separation from other objects is obtained in the (H-Ks) vs. (J-H) diagram. We calculated the emission-line contribution to the in-band flux based on a model for NGC 6720: we find that this is highest in the Z and Y bands at over 50%, lower in the J band at 40%, and lowest in the H and Ks bands at 20%. A new view of PNe in the wavelength domain of the Z and Y bands is shown. Photo-ionisation models are used to explore the observed colours in these bands. The Y band is shown to be dominated by He i 1.083 μm and He II 1.012 μm, and colours involving this band are very sensitive to the temperature of the ionizing star. Conclusions. The VVV survey represents a unique dataset for studying crowded and obscured regions in the Galactic plane. The diagnostic diagrams presented here allow one to study the properties of known PNe and to uncover objects not previously classified., Facultad de Ciencias Astronómicas y Geofísicas, Instituto de Astrofísica de La Plata

We present the discovery of 6 nebular objects made by amateur astronomers. Four of these discoveries are clearly planetary nebulae (PNe), one is a possible PN, and another is a likely H II region. The bipolar nebula Ou4 presents the largest angular extent ever found : over one degree on the sky! We consider various scenarios that could explain such a nebula. Ou4 could be one of the nearest PNe known, though its possible PN nature will need confirmation., Accepted by Rev.Mex.AA; 18 pages,8 figures

Context. Detections of molecular lines, mainly from H₂ and CO, reveal molecular material in planetary nebulae. Observations of a variety of molecules suggest that the molecular composition in these objects differs from that found in interstellar clouds or in circumstellar envelopes. The success of the models, which are mostly devoted to explain molecular densities in specific planetary nebulae, is still partial however. Aims. The present study aims at identifying the influence of stellar and nebular properties on the molecular composition of planetary nebulae by means of chemical models. A comparison of theoretical results with those derived from the observations may provide clues to the conditions that favor the presence of a particular molecule. Methods. A self-consistent photoionization numerical code was adapted to simulate cold molecular regions beyond the ionized zone. The code was used to obtain a grid of models and the resulting column densities are compared with those inferred from observations. Results. Our models show that the inclusion of an incident flux of X-rays is required to explain the molecular composition derived for planetary nebulae. We also obtain a more accurate relation for the N(CO)/N(H₂) ratio in these objects. Molecular masses obtained by previous works in the literature were then recalculated, showing that these masses can be underestimated by up to three orders of magnitude. We conclude that the problem of the missing mass in planetary nebulae can be solved by a more accurate calculation of the molecular mass.

"Optical spectroscopy of the entire planetary nebula M 1-9, reveals pronounced density variations, a temperature distribution where Te(N+) is larger than Te(O+2) and abundances indicating that it is a halo planetary nebulae, an association supported by it is very large radial velocity and distance to the galactic plane. The ionized mass is between 0.1 and 0.4 M☉. A uniform density photoionization model (Cloudy, version 10.00) reproduced most of the spectrum, but the intensity of [O III] 4363 °A is much larger than observed. In this model, nebular abundances are smaller than those derived using standard techniques and the stellar temperature and luminosity are 84900ºK and 1025 L☉, which implies that the progenitor probably was a =1 M☉ zero-age main sequence star."

The University of ManchesterFaculty of Engineering and Physical SciencesABSTRACT OF THESIS submitted by Bryan ReesFor the degree of Doctor of Philosophyand entitled "A study of planetary nebulae in and towards the Galactic Bulge"Date of submission 30/06/2011A planetary nebula (PN) consists of material, mainly gas, that has been ejected from a star on the asymptotic giant branch of its life cycle. This material emits electromagnetic radiation due to photoionization and recombination, collisional and radiative excitation or free-free radiation. The envelope of material moves outwards from the central star and may take one of a variety of shapes. These shapes are believed to be sculpted by the stellar wind, magnetic fields and interactions with a binary companion. However, within a time scale of as little as 10 000 years the nebula fades from view and merges with the interstellar medium.Similar variations in the shape of planetary nebulae (PNe) can be seen in both the Galactic Bulge and Disc and in the Magellanic Clouds. It is therefore reasonable to assume that the shaping process is universal. By classifying PNe by morphology and relating those shapes to other nebular properties we have attempted to derive information about that shaping process.We have used photometric narrowband observations of a sample of PNe listed in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae to investigate the relationship between PN morphology and the other PN characteristics. The high resolution images were made using ESO's New Technology Telescope and the Hubble Space Telescope. The information we could obtain directly from the observations was augmented by information in the literature in order to address that question. The observations were used to classify the morphologies of 154 PNe, to estimate the sizes of 138 of those nebulae that we considered to lie within the Galactic Bulge, to determine the orientations of 130 of those Bulge nebulae and to derive photometric fluxes for the 69 PNe which had observations of standard stars made during the same night. Information on central star binarity, nebular abundances and radial and expansion velocity was obtained from the literature.Our photometrically derived PNe line fluxes were used to verify 59 H-beta and 69 [OIII] catalogued values (which were obtained using spectroscopy). We found sufficient discrepancy between the values for 9 PNe to merit a further check taking place.We found no distinguishing relationship between PN morphology and any of PN size, radial velocity, or angular location within the Bulge. The abundances of He and O, and the N/O ratio, are generally lower in bipolar nebulae than in those nebulae with no apparent internal structure. We are unable to come to any conclusion as to a relationship between PN morphology and stellar metallicity.Given the short lifespan of PNe and the age of the Bulge it appears that almost all PNe in the Bulge must be associated with low mass stars. The high ratio of bipolar PNe we found in our Bulge sample suggests that, at least within the Bulge, bipolar nebulae are not necessarily associated with high mass stars. Our results show that unlike the orientations of other types of PNe the orientations of the bipolar nebulae in the Bulge are not randomly distributed. Measured to a line tip to tip along the lobes they peak and have their mean approximately along the Galactic Plane. This suggests that the bipolar PNe originate in a different environment from other morphological types, perhaps related to binary separation. However, we find that bipolarity does not imply common-envelope evolution. If the hypothesis that bipolar nebulae are formed in binary star systems is correct, binary systems in the Galactic Bulge have angular momentum vectors that are preferentially aligned along the Galactic Plane. As the orientation appears to be unrelated to lobe size and hence nebular age, the alignment implies that the non-random nature of the angular momentum vectors originated at the time the Bulge stellar population formed. We suggest that it is due to the direction and strength of the ambient magnetic fields.

"We present kinematic data for 211 bright planetary nebulae in eleven Local Group galaxies: M31 (137 PNe), M32 (13), M33 (33), Fornax (1), Sagittarius (3), NGC 147 (2), NGC 185 (5), NGC 205 (9), NGC 6822 (5), Leo A (1), and Sextans A (1). The data were acquired at the Observatorio Astronómico Nacional in the Sierra de San Pedro Mártir using the 2.1 m telescope and the Manchester Echelle Spectrometer in the light of [O III]¿5007 at a resolution of 11 km s-1. A few objects were observed in H¿. The internal kinematics of bright planetary nebulae do not depend strongly upon the metallicity or age of their progenitor stellar populations, though small systematic differences exist. The nebular kinematics and H¿ luminosity require that the nebular shells be accelerated during the early evolution of their central stars. Thus, kinematics provides an additional argument favoring similar stellar progenitors for bright planetary nebulae in all galaxies."

Aims. We aim to study the physical conditions, particularly the excitation state, of the intermediate-temperature gas components in the protoplanetary nebula CRL 618. These components are particularly important for understanding the evolution of the nebula. Methods. We performed Herschel/HIFI observations of several CO lines in the far-infrared/sub-mm in the protoplanetary nebula CRL 618. The high spectral resolution provided by HIFI allows measurement of the line profiles. Since the dynamics and structure of the nebula is well known from mm-wave interferometric maps, it is possible to identify the contributions of the different nebular components (fast bipolar outflows, double shells, compact slow shell) to the line profiles. The observation of these relatively high-energy transitions allows an accurate study of the excitation conditions in these components, particularly in the warm ones, which cannot be properly studied from the low-energy lines. Results. The 12CO J = 16−15, 10−9, and 6−5 lines are easily detected in this source. Both 13CO J = 10−9 and 6−5 are also detected.Wide profiles showing spectacular line wings have been found, particularly in 12CO J = 16−15. Other lines observed simultaneously with CO are also shown. Our analysis of the CO high-J transitions, when compared with the existing models, confirms the very low expansion velocity of the central, dense component, which probably indicates that the shells ejected during the last AGB phases were driven by radiation pressure under a regime of maximum transfer of momentum. No contribution of the diffuse halo found from mm-wave data is identified in our spectra, because of its low temperature. We find that the fast bipolar outflow is quite hot, much hotter than previously estimated; for instance, gas flowing at 100 km s−1 must have a temperature higher than ∼200 K. Probably, this very fast outflow, with a kinematic age

8 páginas, 5 figuras, 3 tablas.-- El Pdf del artículo es la versión pre-print: arXiv:1006.2398v1.-- et al., [Context]: The link between how bipolar planetary nebulae are shaped and their central stars is still poorly understood. [Aims]: This paper investigates the kinematics and shaping of the multipolar nebula M 1–75, and briefly discusses the location and nature of its central star. [Methods]: Fabry-Perot data from GHαFAS on the WHT that samples the Doppler shift of the [Nii] 658.3 nm line are used to study the dynamics of the nebula by means of a detailed 3D spatio-kinematical model. Multi-wavelength images and spectra from the WFC and IDS on the INT, as well as from ACAM on the WHT, allowed us to constrain the parameters of the central star. [Results]: The two pairs of lobes, angularly separated by ~22°, were ejected simultaneously approx. ~3500–5000 years ago, at the adopted distance range from 3.5 to 5.0 kpc. The larger lobes show a slight degree of point symmetry. The formation of the nebula could be explained by wind interaction in a system consisting of a post-AGB star surrounded by a disc warped by radiative instabilities. This requires the system to be a close binary or a single star that engulfed a planet as it died. On the other hand, we present broad- and narrow-band images and a low S/N optical spectrum of the highly-reddened, previously unnoticed star that is likely the nebular progenitor. Its estimated V–I colour allows us to derive a rough estimate of the parameters and nature of the central star.

Context. There are more than 3000 confirmed and probable known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims. We undertook a spectroscopic survey of central stars of PNe at low resolution and compiled a large list of central stars for which information was dispersed in the literature. Methods. We observed 45 PNs using the 2.15 m telescope at Casleo, Argentina. Results. We present a catalogue of 492 confirmed and probable CSPN and provide a preliminary spectral classification for 45 central star of PNe. This revises previous values of the proportion of CSPN with atmospheres poor in hydrogen in at least 30% of cases and provide statistical information that allows us to infer the origin of H-poor stars., Instituto de Astrofísica de La Plata, Facultad de Ciencias Astronómicas y Geofísicas

Either by collimating a fast stellar wind or by driving a jet via accretion in the central system, dusty torii or stable disks may be crucial ingredients for the shaping of PNe. We study the dust distribution in the very young Proto-Planetary Nebule (PPN) IRAS16342-3814, also known as the Water Fountain Nebula, which is known to show strong bipolar characteristics in the shape of two reflection lobes, and high-velocity collimated molecular outlfows. We use the new Mid-IR (MIR) instrument VISIR on the Very Large Telescope (VLT) both in imaging and spectroscopy mode at wavelengths from 8 to 13 micron. We present the first spatially resolved MIR observations of a dusty evolved star obtained with VISIR and find that the improved spatial resolution contradicts previous claims of an elliptical brightness distribution at the heart of IRAS16342: we find the waist region to be dark even in the MIR. We show that the filling angle of the obscuring dust lane, which is made mostly of amorphous silicates, is very large, possibly even close to a spherically symmetric superwind as seen in OH/IR stars. We conclude that, in contrast to the multitude of recent dusty-disk detections in Post-AGB stars and PNe, IRAS16342 does not show this extreme equatorial density enhancement, at least not on the scale of the dusty environment which lends the object its IR appearance. Rather, it appears that the observed precessing jets are shaping the bipolar nature in the remains of a spherically symmetric AGB superwind., 5 pages, accepted for publication in A&A

We present high resolution spectroscopy in the [\ion{O}{3}]$\lambda$5007 and H$\alpha$ lines of bright planetary nebulae in the Milky Way bulge and the dwarf galaxies M32, Fornax, Sagittarius, and NGC 6822 obtained at the Observatorio Astronomico Nacional in the Sierra San Pedro Martir using the Manchester Echelle Spectrograph. We use the high signal-to-noise (S/N) observations of Milky Way bulge planetary nebulae to explore what kinematic information can be determined reliably when observing extragalactic planetary nebulae in the [\ion{O}{3}]$\lambda$5007 line at modest S/N. We find that the intrinsic line widths measured in [\ion{O}{3}]$\lambda$5007 and H$\alpha$ are very similar. Over the range of S/N available in this sample, the line width we measure is independent of the S/N. Finally, deviations from a Gaussian line shape are small. Thus, the line width of the [\ion{O}{3}]$\lambda$5007 line in bright extragalactic planetary nebulae should reflect the kinematics of most of the mass in the ionized nebular shell., Comment: accepted for publication in the october 2009 issue of Revista Mexicana de Astronomia y Astrofisica

Aims. We present asteroseismological inferences on RX J2117.1+3412, the hottest known pulsating PG 1159 star. Our results are based on full PG 1159 evolutionary models recently presented by Miller Bertolami & Althaus (2006). Methods. We performed extensive computations of adiabatic g-mode pulsation periods on PG 1159 evolutionary models with stellar masses ranging from 0.530 to 0.741 M⊙. PG 1159 stellar models are extracted from the complete evolution of progenitor stars started from the ZAMS, through the thermally pulsing AGB and born-again phases to the domain of the PG 1159 stars. We constrained the stellar mass of RX J2117.1+3412 by comparing the observed period spacing with the asymptotic period spacing and with the average of the computed period spacings. We also employed the individual observed periods to find a representative seismological model for RX J2117.1+3412. Results. We derive a stellar mass M* ∼ 0.56-0.57 M⊙ from the period spacing data alone. In addition, we found a best-fit model representative for RX J2117.1+3412 with an effective temperature Teff = 163 400 K, a stellar mass M* = 0.565 M⊙, and a surface gravity log g = 6.61. The derived stellar luminosity and radius are log (L*/L ⊙) = 3.36 and log (R*/R⊙) = -1.23, respectively, and the He-rich envelope thickness is Menv = 0.02 M⊙. We derive a seismic distance d ∼ 452 pc and a linear size of the planetary nebula DPN ∼ 1.72 pc. These inferences seem to solve the discrepancy between the RX J2117.1+3412 evolutionary timescale and the size of the nebula. All of the seismological tools we use concur to the conclusion that RX J2117.1+3412 must have a stellar mass M* ∼ 0.565 M⊙, much in agreement with recent asteroseismology studies and in clear conflict with the predictions of spectroscopy plus evolutionary tracks., Este documento tiene una corrección (ver documento relacionado)., Facultad de Ciencias Astronómicas y Geofísicas, Instituto de Astrofísica de La Plata

"We show that SBS 1150+599A is most probably a planetary nebula located in the Galactic halo (becoming PNG135.9+55.9). Our photoionization models indicate that its oxygen abundance is lower than 1/100 solar."

Two sets of observational carbon stellar yields for low-and-intermediate mass stars are computed from planetary nebulae abundances derived from C II $\lambda4267$ and C III $\lambda\lambda1906+1909$ lines, respectively. By comparing C/O values observed in stars of the solar vicinity and Galactic HII regions with those predicted by chemical evolution models for the Galaxy, which assume these observational yields, I conclude that the C abundances derived from permitted lines are better than those derived from forbidden lines., Comment: 2 pages, Proceedings of the conference "Ionized Gaseous Nebulae", Nov 21-24, 2000; RevMexAA in press

Preliminary results from high resolution spectroscopy for a selected sample of planetary nebulae with WR nucleus or weak{emission line star (wels) are presented. The observed objects spread over a wide range in stellar characteristics: early and late [WC]{type stars and wels have been selected. Nebular densities and temperatures, as well as ionic and total abundances and expansion velocities, have been derived. The results are used to perform a statistical study of the objects in order to nd possible relationships among the dierent stellar and nebular parameters and to analyze the eect of the WR wind on the nebular shell.

By collecting distances from the literature, a set of 73 planetary nebulae with mean distances of high accuracy is derived. This sample is used for recalibration of the mass-radius relationship, used by many statistical distance methods. An attempt to correct for a statistical peculiarity, where errors in the distances influences the mass--radius relationship by increasing its slope, has been made for the first time. Distances to PNe in the Galactic Bulge, derived by this new method as well as other statistical methods from the last decade, are then used for the evaluation of these methods as distance indicators. In order of achieving a Bulge sample that is free from outliers we derive new criteria for Bulge membership. These criteria are much more stringent than those used hitherto, in the sense that they also discriminate against background objects. By splitting our Bulge sample in two, one with optically thick (small) PNe and one with optically thin (large) PNe, we find that our calibration is of higher accuracy than most other calibrations. Differences between the two subsamples, we believe, are due to the incompleteness of the Bulge sample, as well as the dominance of optical diameters in the ``thin'' sample and radio diameters in the ``thick'' sample. Our final conclusion is that statistical methods give distances that are at least as accurate as the ones obtained from many individual methods. Also, the `long' distance scale of Galactic PNe is confirmed., 15 pages, 9 figures, accepted for publication in A&A

"A self-consistent scenario to explain the morphology of planetary nebulae ispresented. This scenario is consistent with the Galactic distribution of di?erentnebular types. This work addresses several controversial features that appear inplanetary nebulae, which are easily solved by the inclusion of MHD e?ects. Thesefeatures include the presence of axisymmetric and collimated outows with linearlyincreasing kinematics, and the existence of asymmetrical morphologies suchas point-symmetric nebulae."