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|The relation between Zanstra temperature and morphology in planetary nebulae|
We have created a master list of Zanstra temperatures for 373 galacticplanetary nebulae based upon a compilation of 1575 values taken from thepublished literature. These are used to evaluate mean trends intemperature for differing nebular morphologies. Among the most prominentresults of this analysis is the tendency forη=TZ(HeII)/TZ(HeI) to increase with nebularradius, a trend which is taken to arise from the evolution of shelloptical depths. We find that as many as 87 per cent of nebulae may beoptically thin to H ionizing radiation where radii exceed ~0.16 pc. Wealso note that the distributions of values η and TZ(HeII)are quite different for circular, elliptical and bipolar nebulae. Acomparison of observed temperatures with theoretical H-burning trackssuggests that elliptical and circular sources arise from progenitorswith mean mass ≅ 1 Msolar(although the elliptical progenitors are probably more massive).Higher-temperature elliptical sources are likely to derive fromprogenitors with mass ≅2 Msolar, however, implying thatthese nebulae (at least) are associated with a broad swathe ofprogenitor masses. Such a conclusion is also supported by trends in meangalactic latitude. It is found that higher-temperature ellipticalsources have much lower mean latitudes than those with smallerTZ(HeII), a trend which is explicable where there is anincrease in with increasing TZ(HeII).This latitude-temperature variation also applies for most other sources.Bipolar nebulae appear to have mean progenitor masses ≅2.5Msolar, whilst jets, Brets and other highly collimatedoutflows are associated with progenitors at the other end of the massrange (~ 1 Msolar). Indeed it ispossible, given their large mean latitudes and low peak temperatures,that the latter nebulae are associated with the lowest-mass progenitorsof all.The present results appear fully consistent with earlier analyses basedupon nebular scale heights, shell abundances and the relativeproportions of differing morphologies, and offer further evidence for alink between progenitor mass and morphology.
|Redshift-Distance Survey of Early-Type Galaxies: Spectroscopic Data|
We present central velocity dispersions and Mg2 line indicesfor an all-sky sample of ~1178 elliptical and S0 galaxies, of which 984had no previous measures. This sample contains the largest set ofhomogeneous spectroscopic data for a uniform sample of ellipticalgalaxies in the nearby universe. These galaxies were observed as part ofthe ENEAR project, designed to study the peculiar motions and internalproperties of the local early-type galaxies. Using 523 repeatedobservations of 317 galaxies obtained during different runs, the dataare brought to a common zero point. These multiple observations, takenduring the many runs and different instrumental setups employed for thisproject, are used to derive statistical corrections to the data and arefound to be relatively small, typically <~5% of the velocitydispersion and 0.01 mag in the Mg2 line strength. Typicalerrors are about 8% in velocity dispersion and 0.01 mag inMg2, in good agreement with values published elsewhere.
|Redshift-Distance Survey of Early-Type Galaxies: Circular-Aperture Photometry|
We present R-band CCD photometry for 1332 early-type galaxies, observedas part of the ENEAR survey of peculiar motions using early-typegalaxies in the nearby universe. Circular apertures are used to tracethe surface brightness profiles, which are then fitted by atwo-component bulge-disk model. From the fits, we obtain the structuralparameters required to estimate galaxy distances using theDn-σ and fundamental plane relations. We find thatabout 12% of the galaxies are well represented by a pure r1/4law, while 87% are best fitted by a two-component model. There are 356repeated observations of 257 galaxies obtained during different runsthat are used to derive statistical corrections and bring the data to acommon system. We also use these repeated observations to estimate ourinternal errors. The accuracy of our measurements are tested by thecomparison of 354 galaxies in common with other authors. Typical errorsin our measurements are 0.011 dex for logDn, 0.064 dex forlogre, 0.086 mag arcsec-2 for<μe>, and 0.09 for mRC,comparable to those estimated by other authors. The photometric datareported here represent one of the largest high-quality and uniformall-sky samples currently available for early-type galaxies in thenearby universe, especially suitable for peculiar motion studies.Based on observations at Cerro Tololo Inter-American Observatory (CTIO),National Optical Astronomy Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation (NSF);European Southern Observatory (ESO); Fred Lawrence Whipple Observatory(FLWO); and the MDM Observatory on Kitt Peak.
|Infrared Imaging and Optical Imaging and Spectroscopy of (mostly) Type I Planetary Nebulae. I.|
Optical spectra, images in the main optical emission lines and IR imagesdirected towards the detection of molecular hydrogen, were obtained for14 planetary nebulae (PNe). It was found that nine of these comply withthe two criteria defining a type I PNe (He-rich with a large N/O ratio).All of these objects are bipolar and, with the exception of Sh 2-71,show shocked molecular hydrogen. The chemical composition of JnEr 1indicates it was produced by a massive progenitor, and it can betentatively classified as a type I PN. A 26 is a helium rich ellipticalPN with a low N/O abundance ratio, probably without H2.Shocked H2 was found in K 3-92, an elliptical type IIb PN,which implies that this object is probably young. The chemicalcomposition of K 3-72, K 4-55, M 1-75, and Sh 2-71 indicate that thirddredge-up episodes occurred in their progenitor star. The temperaturesand spectral properties of BV 5-1, K 4-55, M 1-41, M 1-75, and Sh 2-71suggest the presence of shock waves in their ionized component.
|Nearby Optical Galaxies: Selection of the Sample and Identification of Groups|
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
|Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies|
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
|H2 Emission from Planetary Nebulae: Signpost of Bipolar Structure|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJ...462..777K&db_key=AST
|ROSAT observations of EUV-bright planetary nebula central stars|
We present the observations of the five planetary nebula central starsdetected during the ROSAT Wide Field Camera all-sky survey. These dataare supplemented with ROSAT Position Sensitive Proportional Countersurvey data and follow-up ROSAT observations obtained during the pointedphase. We subject these data to analysis with NLTE model atmospheresincluding continuous opacity from H, He, C, N and O. Our choices ofsurface gravity and abundances are constrained by optical data whenknown. We find that, although the general level of emission can beexplained by photospheric emission from the hot stars, the fits are notparticularly good or unique and are very model dependent. Thebest-fitting effective temperatures for the central stars are comparedwith those derived from other methods. Interstellar columns are comparedwith those we have obtained from new 21-cm emission line spectra.
|The environment and the origin of twisting in early-type galaxies|
The effects of random collisions in groups or clusters on thedevelopment of isophotal twisting (IT) in early-type galaxies areinvestigated. The maximum ellipticity and IT in each galaxy is estimatedon the basis of published observational data and correlated with thegalaxy number density. The proportions of S0 and elliptical (E) galaxieswith IT are found to be independent of local environmental density. CCDobservations of six isolated nonhierarchical pairs containing early-typegalaxies, obtained at the Cassegrain focus of the 1.82-m telescope atAsiago Observatory, are then used to study tidal interactions ingalaxies with normal morphology; the data are presented in tables andgraphs and examined in detail. It is shown that mutual tidalperturbations alone cannot explain the IT phenomena: S0 galaxies areless twisted than Es in all density regimes, and the proportion oftwisted Es in E+E pairs is similar to that in the overall sample.
|A 21 centimeter line survey of a complete sample of interacting and isolated galaxies|
The paper presents 21 cm line observations of a complete sample ofinteracting and isolated galaxies made with the National Radio AstronomyObservatory 91 and 43 m telescopes and the Arecibo 3035 m telescope. The21 cm line data are combined with a homogeneous set of optical data onangular diameters, axial ratios, magnitudes, and colors, and integralproperties are calculated for the galaxies in both samples. In thispaper, the sample selection procedures, the method of observation, thedata reduction, and the observational errors are described. Thedetection percentages are presented for both samples.
|Double galaxy investigations. I - Observations|
Redshift information from 240 A/mm spectrograms is presented for 370double arcsec galaxy systems from the Karachentsev (1972) catalog,including all pairs in that catalog with separation less than 80 arcsec.An extensive error discussion utilizing internal and external (21 cm)comparisons provides calibration of systematic error and determines theuncertainty for a typical high weight optical redshift to be plus orminus 65 km/sec. Internal differential redshifts within single spectrausing common lines achieve accuracies of 18-30 km/sec, depending uponseparation, and are available for about 200 pairs. Extensive informationon emission and other properties is also provided.
|Optical redshifts of 59 galaxies|
This paper presents the results of an observing program carried out tomeasure galaxy redshifts with the Cassegrain Digicon Spectrograph systemon the McDonald Observatory 2.1 m Struve telescope. New redshiftdeterminations are presented for 59 galaxies, obtained for emission linespectra by conventional wavelength determination techniques and forabsorption line spectra by Fourier transform filtering and crosscorrelation techniques with respect to velocity standard spectra of NGC3115 and NGC 4736. With respect to published redshifts for 29 galaxies,the new redshifts show a mean residual of -1 km/sec and rms residual of49 km/sec, without apparent systematic trends, from -300 to +13,700km/sec.
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