%R 1998A&AS..129..205L
%J-217
%A Lieske J.H.
%T Galilean satellite ephemerides E5.
%M ds6503
%F 1998.04.08
%B New ephemerides of Jupiter's Galilean satellites are produced from an analysis of CCD astrometric data, Voyager-mission optical navigation images, mutual event observations, photographic plates, and eclipse timing observations. The resulting parameters, for use in the galsat computer software, are in the B1950 frame for use by the Galileo space mission. Results in the J2000 system are also available.
%K astrometry - celestial mechanics - ephemerides - Planets and satellites: Jupiter

%R 1998A&AS..129..219D
%J-236
%A Dallacasa D., Bondi M., Alef W., Mantovani F.
%T European VLBI Network dual frequency observations of CSS-GPS candidates.
%M ds1451
%F 1998.04.08
%B We present the results of S/X (2.3/8.3 GHz) VLBI snapshot observations of 28 sources drawn from a list of Compact Steep-Spectrum (CSS) and GHz-Peaked Spectrum (GPS) candidates by Dallacasa & Stanghellini (1991, in Proc. of "Compact Steep-Spectrum and GHz-Peaked Spectrum Radio Sources.", p. 224) with additional sources from Barthel et al. (1988A&AS...73..515B) and from Wills (1979ApJS...39..291W). The experiment was carried out with 4 stations of the European VLBI Network (EVN) with the addition of two geodetic antennas. Typical resolutions were about 30x12mas and 9x3.5mas at S
and X bands respectively. Only one source was not detected. Due to the limited uv-coverage of the data, only simple structures could be imaged.
%K galaxies: active; galaxies: jets; galaxies: nuclei; (galaxies:) quasars: general; radio continuum: galaxies

%R 1998A&AS..129..237F
%J-266
%A Feltzing S., Gustafsson B.
%T Abundances in metal-rich stars. Detailed abundance analysis of 47 G and K dwarf stars with [Me/H] > 0.10 dex.
%M h0567
%F 1998.04.08
%B We have derived elemental abundances of O, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Co, Ni as well as for a number of s-elements for 47 G and K dwarf, with [Me/H]>0.1dex. The selection of stars was based on their kinematics as well as on their uvby-{beta} photometry. One sample of stars on rather eccentric orbits traces the chemical evolution interior to the solar orbit and another, on circular orbits, the evolution around the solar orbit. A few Extreme Population I stars were
included in the latter sample.
The stars have -0.1dex<[Fe/H]<0.42dex. The spectroscopic [Fe/H] correlate well with the [Me/H] derived from uvby-{beta} photometry. We find that the elemental abundances of Mg, Al, Si, Ca, Ti, Cr and Ni all follow [Fe/H]. Our data put further constraints on models of galactic chemical evolution, in particular of Cr, Mn and Co which have not previously been studied for dwarf stars with [Me/H]>0.1 dex. The increase in [Na/Fe] and [Al/Fe] as a function of [Fe/H] found
previously by Edvardsson et al. (1993a) has been confirmed for [Na/Fe]. This upturning relation, and the scatter around it, are shown not to be due to a mixture of populations with different mean distances to the galactic centre. We do not confirm the same trend for aluminium, which is somewhat surprising since both these elements are thought to be produced in the same environments in the pre-supernova stars. Nor have we been able to trace any tendency for relative abundances
of O, Si, and Ti relative to Fe to vary with the stellar velocities, i.e. the stars present mean distance to the galactic centre. These results imply that there is no significant difference in the chemical evolution of the different stellar populations for stars with [Me/H]>0.1dex. We find that [O/Fe] continue to decline with increasing [Fe/H] and that oxygen and europium correlate well. However [Si/Fe] and [Ca/Fe] seem to stay constant. A real ("cosmic") scatter in
[Ti/Fe] at given [Fe/H] is suggested as well as a decreasing abundance of the s-elements relative to iron for the most metal-rich dwarf stars. We discuss our results in the context of recent models of galactic chemical evolution. In our sample we have included a few very metal rich stars, sometimes called SMR (super metal rich) stars. We find these stars to be among the most iron-rich in our sample but far from as metal-rich as indicated by their photometric metallicities.
SMR stars on highly eccentric orbits, alleged to trace the evolution of the chemical evolution in the galactic Bulge, have previously been found overabundant in O, Mg and Si. We have included three such stars from the study by Barbuy & Grenon (1990). We find them to be less metal rich and the other elemental abundances remain puzzling. Detailed spectroscopic abundance analyses of K dwarf stars are rare. Our study includes 5 K dwarf stars and has revealed what appears to be
a striking example of overionization. The overionization is especially prominent for Ca, Cr and Fe. The origin of this apparent overionization is not clear and we discuss different explanations in some detail.
%K Galaxy: abundances - evolution - stars: abundances - late-type - fundamental parameters

%R 1998A&AS..129..267C
%J-279
%A Cassisi S., Castellani V., Degl'Innocenti S., Weiss A.
%T An updated theoretical scenario for globular cluster stars.
%M h0423
%F 1998.04.08
%B In the first part of this paper we revisit the history of theoretical predictions for HB luminosities in old Population II stellar clusters, starting from the results of "old" evolutionary computations to introduce in various steps all the available "new" physics. We discuss the influence of physical ingredients on selected evolutionary parameters, finally presenting models which incorporate all the most recent updating of the relevant physics. The evolutionary behavior
of such models is extensively investigated for selected choices about the cluster metallicity, discussing theoretical predictions concerning both cluster isochrones and the calibration of the parameter R in terms of the original amount of He in stellar matter. One finds that the "new" physics has a relevant influence on both these parameters, moving cluster ages into a much better agreement with current cosmological evaluations. This scenario is implemented by a further set
of stellar models where element diffusion is taken into account. The comparison between theoretical scenarios with or without diffusion is presented and discussed. A discussion of current observational constraints in the light of the updated theory closes the paper.
%K stars: evolution; general; fundamental parameters; horizontal-branch

%R 1998A&AS..129..281D
%J-288
%A Durret F., Felenbok P., Lobo C., Slezak E.
%T A catalogue of velocities in the cluster of galaxies Abell 85.
%M ds1400
%F 1998.04.08
%B We present a catalogue of velocities for 551 galaxies (and give the coordinates of 39 stars misclassified as galaxies in our photometric plate catalogue) in a region covering about 100'x100' (0.94x0.94Mpc for an average redshift of 0.0555, assuming H_0_=50km/s/Mpc) in the direction of the rich cluster ABCG 85. This catalogue includes previously published redshifts by Beers et al. (1991AJ....102.1581B) and Malumuth et al. (1992AJ....104..495M), together with our 367 new
measurements. A total of 305 galaxies have velocities in the interval 13350-20000km/s, and will be considered as members of the cluster. ABCG 85 therefore becomes one of the clusters with the highest number of measured redshifts; its optical properties are being investigated in a companion paper.
%K galaxies: clusters: individual: ABCG 85; galaxies: distances and redshifts - instrumentation: spectrographs

%R 1998A&AS..129..289M
%J-311
%A Moujtahid A., Zorec J., Hubert A.M., Garcia A., Burki G.
%T Long-term visual spectrophotometric behaviour of Be stars.
%M ds6252
%F 1998.04.08
%B The long-term spectrophotometric variations of 49 Be stars are studied using the U and V magnitudes of the UBV system, the total Balmer discontinuity D and the visible gradient {PHI}_rb_. BCD spectrophotometric and photometric data in five different photometric systems, obtained in most cases since 1950 and reduced to the BCD system, were used. The (U,D), (V,D), ({PHI}_rb_,D) and ({PHI}_rb_,V) correlations obtained differ from star to star and they can be single or
double-valued. They differ clearly for Be phases or Be-shell phases. Be stars with small Vsin i showing the "spectrophotometric shell behaviour": D>D_*_, were found. This finding implies either that strongly flattened models of circumstellar envelopes are in doubt for these stars, or that not all Be stars are rapid rotators. Comparison of observed variations with those predicted for model Be stars with spherical circumstellar envelopes of variable densities and dimensions
implies that spectrophotometric patterns of Be phases are due to circumstellar envelopes in low opacity regimes, while those of spectrophotometric shell phases are due to circumstellar envelopes in high opacity regimes. In a given star, the envelope regions responsible for the observed variations of D and {PHI}_rb_ in spectrophotometric shell phases seem to be smaller and denser than those producing the observed variations of these parameters in spectrophotometric Be phases.
The high positive RV found in strong shell phases might favor the formation of compact circumstellar layers near the star.
%K stars: variable - stars: Be

%R 1998A&AS..129..313B
%J-328
%A Bremnes T., Binggeli B., Prugniel P.
%T Structure and stellar content of dwarf galaxies. I. B and R photometry of dwarf galaxies in the M 81 group.
%M ds1456
%F 1998.04.08
%B We have carried out CCD photometry in the Cousins B and R bands of 25 dwarf galaxy members and suspected members of the M 81 group of galaxies. Based on azimuthally averaged brightness profiles we have derived total magnitudes, effective radii, effective surface brightnesses, as well as galaxy diameters at various isophotal levels in both photometric bands. Best-fitting exponential parameters and B - R colour gradients are also given for these galaxies. The data will be
interpreted, along with those of another supplementary paper, in Paper III of this series (to appear in the main journal). In two appendices we discuss the nature of a clustering of unusual low-surface brightness objects in the south-east corner of the M 81 group and show the luminosity function of its presently known members.
%K galaxies: general - galaxies: fundamental parameters - galaxies: photometry - galaxies: irregular - galaxies: clusters: \object{M 81} group

%R 1998A&AS..129..329B
%J-336
%A Beck R., Berkhuijsen E.M., Hoernes P.
%T A deep {lambda}20 cm radio continuum survey of M 31.
%M ds1238
%F 1998.04.08
%B We present a survey of the total and linearly polarized radio continuum emission of the Andromeda galaxy at 20 cm wavelength with the VLA-D array. 7 fields were observed with 45" angular resolution. The missing large-scale total emission observed with the Effelsberg telescope was inserted. This survey is the most sensitive radio continuum survey of M 31 so far and the first one in linear polarization with the VLA. The total emission of M 31 comes from extended regions and
point sources. Both components are concentrated in the bright "ring" of maximum star formation at about 10 kpc radius. Nearly half of the extended emission emerges from numerous filamentary features which are typically a few arcminutes long (=~600pc). In the field of M 31, 36 linearly polarized background sources were detected. The smallest degrees of polarization occur on the centre of the "ring" where the total emission is highest, hence on the spiral arms as
delineated by H{alpha} emission and OB associations. The distribution of polarization angles reveals coherent features of typically 1 kpc in extent, some of which show a relation to an OB association.
%K techniques: interferometric - galaxies: individual: M 31 - galaxies: magnetic fields - radio continuum: galaxies - polarization

%R 1998A&AS..129..337H
%J-341
%A Harder S., Bertout C., Mennessier C.
%T CCD photometry of YY Orionis stars.
%M ds1422
%F 1998.04.08
%B Photometric UBVRI observations of the YY Orionis stars YY Ori, SY Ori, CE Ori, NS Ori and XX Ori are presented. The luminosity of all stars is variable on a timescale of a few days. This variation is rather irregular and no periodic variability was observed in the present data sets. The V-I and V-R colors become redder when the stars become fainter, suggesting that inhomogeneous surface temperature distributions are responsible for the observed irregular variability. Two stars
located in the vicinity of our program stars and observed in the same frames turned out to be variable. They were identified as V481 Ori and AO Ori. We report a periodic modulation of the V481 Ori light curve with a period of 4.9 days.
%K stars: pre-main sequence - stars: activity - stars: variables: other

%R 1998A&AS..129..343P
%J-351
%A Pons J.A., Miralles J.A., Ibanez J.M.
%T Legendre expansion of the {vec}({nu}{nu}) <-> e^+^ e^-^ kernel: Influence of high order terms.
%M ds6306
%F 1998.04.08
%B We calculate the Legendre expansion of the rate of the process {nu}+ {nu} <->e^+^ + e^-^ up to 3^rd^ order extending previous results of other authors which only consider the 0^th^ and 1^st^ order terms. Using different closure relations for the moment equations of the radiative transfer equation we discuss the physical implications of taking into account quadratic and cubic terms on the energy deposition outside the neutrinosphere in a simplified model. The main
conclusion is that 2^nd^ order is necessary in the semi-transparent region and gives good results if an appropriate closure relation is used.
%K radiation mechanisms: thermal - radiative transfer - stars: neutron - supernovae: general - nuclear reactions

%R 1998A&AS..129..353L
%J-355
%A Li Z.X.
%T Measurements of interannual variation of the vertical at Jozefoslaw by astrometric and gravimetric observations.
%M ds6153
%F 1998.04.08
%B Jozefoslaw astronomical and geodetical observatory at Warsaw is the place where parallel observations of astrometric latitude (since 1959) and meridional plumb line variations from gravimetric methods (since 1976) have been carried out continuously over the past 20 years. The observational data at this observatory have been analysed to confirm the reality of the plumb line variation results derived from the astrometric latitude residuals. Cross correlation analyses between
the results of the two techniques have demonstrated that the interannual plumb line variations along the meridian detected by the astrometric technique is in good accordance with those from the gravimetric technique. The results shown in the paper can be considered as evidence of the existence of non-tidal plumb line variations at interannual time scales, of which the scale is about 0.02" in the case of Jozefoslaw observatory, and the possibility in measuring them by
astrometric techniques.
%K earth - reference systems - astrometry

%R 1998A&AS..129..357F
%J-361
%A Faundez-Abans M., de Oliveira-Abans M.
%T On the morphology of peculiar ring galaxies.
%M ds1255
%F 1998.04.08
%B It is proposed that peculiar ring galaxies can be divided into five principal types according to the morphology of the ring and bulge, based on the visual inspection of 489 selected objects. Those objects have been named "peculiar" following the "Catalogue of Southern Peculiar Galaxies and Associations" by Arp & Madore (1986).
%K galaxies: peculiar - fundamental parameters - structure

%R 1998A&AS..129..363J
%J-398
%A Jorissen A., Knapp G.R.
%T Circumstellar shells and mass loss rates: Clues to the evolution of S stars.
%M ds6667
%F 1998.04.08
%B It is the purpose of this paper to rediscuss the circumstellar properties of S stars and to put these properties in perspective with our current understanding of the evolutionary status of S stars, in particular the intrinsic/extrinsic dichotomy. This dichotomy states that only Tc-rich ("intrinsic") S stars are genuine thermally-pulsing asymptotic giant branch stars, possibly involved in the M-S-C evolutionary sequence. Tc-poor S stars are referred to as "extrinsic" S
stars, because they are the cooler analogs of barium stars, and like them, owe their chemical peculiarities to mass transfer across their binary system. Accordingly, an extensive data set probing the circumstellar environment of S stars (IRAS flux densities, maser emission, CO rotational lines) has been collected and critically evaluated. This data set combines new observations (9 stars have been observed in the CO J=2-1 line and 3 in the CO J=3-2 line, with four new
detections) with existing material (all CO and maser observations of S stars published in the literature). The IRAS flux densities of S stars have been re-evaluated by co-adding the individual scans, in order to better handle the intrinsic variability of these stars in the IRAS bands, and possible contamination by Galactic cirrus. In the (K-[12], [25]-[60]) color-color diagram, S stars segregate into five distinct regions according to their Tc content and ZrO/TiO, C/O and
IR spectral indices. Stars with photospheric colors (populating "Region A") may be identified with extrinsic S stars. For the other regions characterized by different excess levels in the 12, 25 and 60 {mu}m bands, several diagnostics (like the IRAS spectral class, maser emission, and shape of CO rotational lines) have been collected to infer the physical properties of the dust shell. A simple radiative-transfer code has also been used to infer the chemical nature
(carbonaceous or silicate) of the dust grains from the observed IR colors. S stars with large K-[12] excesses and moderate [25]-[60] excesses (populating Regions B and C) exhibit the signatures of oxygen-rich shells (9.7{mu}m silicate emission and SiO maser emission). The situation is less clear for S stars with small K-[12] and moderate [25]-[60] indices (populating Regions D and E). Their IR colors are consistent with carbonaceous grains (as is their featureless IRAS
spectrum, and absence of silicate or SiO maser emission), but these features may equally well be explained by a detached shell. For many of these stars with a large 60{mu}m excess, the shell is indeed resolved by the IRAS beam at 60{mu}m. The prototypical SC star FU Mon is among these. Since SC stars are believed to be in a very short-lived evolutionary phase where C/O=1 within 1%, FU Mon may be a good candidate for the "interrupted mass-loss" scenario advocated by Willems 
& de Jong (1988A&A...196..173W). The CO line profile of FU Mon is also peculiar in being quite narrow (V_e_=2.8km/s), suggesting that the mass loss has just resumed in this star. Mass loss rates or upper limits have been derived for all S stars observed in the CO rotational lines, and range from <2x10^-8^M_{sun}_/yr for extrinsic S stars to 1x10^-5^M_{sun}_/yr (the Mira S star W Aql). These mass-loss rates correlate well with the K-[12] color index, which probes the
dust loss rate, provided that {dot}(M)>10^-8^M_{sun}_/yr. Small mass-loss rates are found for extrinsic S stars, consistent with their not being so evolved (RGB or Early-AGB) as the Tc-rich S stars. This result does not support the claim often made in relation with symbiotic stars that binarity strongly enhances the mass-loss rate.
%K stars: mass-loss - stars: AGB - stars: late-type - infrared: stars - radio lines: stars

%R 1998A&AS..129..399K
%J-412
%A Katgert P., Mazure A., den Hartog R., Adami C., Biviano A., Perea J.
%T The ESO Nearby Abell Cluster Survey. V. The catalogue: Contents and instructions for use.
%M ds6559
%F 1998.04.08
%B We present the catalogue resulting from the ESO Nearby Abell Cluster Survey (the ENACS), which contains redshifts and magnitudes for 5634 galaxies in the directions of 107 rich, nearby southern Abell cluster candidates. We describe the contents of the catalogue and discuss the results of a comparison between the ENACS catalogue and the COSMOS Galaxy Catalogue. When cross-correlating the two catalogues we find that, at least in the areas of the ENACS clusters, the
completeness of the COSMOS catalogue is somewhat lower than was estimated previously for the carefully analyzed and well-calibrated part of the COSMOS catalogue known as the Edinburgh-Durham Southern Galaxy Survey (EDSGC). The galaxy positions in the COSMOS and ENACS catalogues are found to be on the same system to within about one arcsecond. For the clusters for which the photometry in the ENACS and COSMOS catalogues is based on the same survey plates, the two magnitude
scales agree very well. We confirm that the photometric calibration in the EDSGC subset of the COSMOS catalogue is of higher quality than in the EDSGC complement. The ENACS galaxy samples are unbiased subsets of the COSMOS catalogue as far as the projected galaxy distribution is concerned, except in only a few cases. We summarize how the ENACS galaxy samples are subsets of the COSMOS catalogues in the ENACS apertures, with respect to magnitude. For the ENACS catalogue as a
whole, we describe the apparent incompleteness at faint magnitudes and towards higher redshifts. Finally, we provide some detailed information about the ENACS catalogue that is essential for its proper statistical use and we summarize some facts that must be remembered when selecting subsets of galaxies from it.
%K galaxies: clusters - galaxies: redshifts - galaxies: photometry - catalogs

%R 1998A&AS..129..413J
%J-423
%A Jimenez A., Gonzalez Jorge H., Rabello-Soares M.C.
%T Diurnal atmospheric extinction over Teide Observatory (Tenerife, Canary Islands).
%M ds6551
%F 1998.04.08
%B Data from five continuous years (1984 to 1989) at Teide Observatory (Izana, Tenerife, Canary Islands) obtained with a full-disc solar multichannel photometer devoted to the detection of solar intensity oscillations has now been used for a detailed study of the extinction coefficient behaviour at several wavelengths (from 450nm to 870nm) and aerosol size distributions under different atmospheric conditions. From this study we conclude that an extinction coefficient around
0.075mag/airmass at 680nm constitutes the borderline between clear days and dusty days affected by the occasional presence of wind-blown Saharan dust. In the former the extinction can vary between 0.04 and 0.07mag/airmass (at 680nm) and in the latter between 0.075 and 0.8mag/airmass (at 680nm). Moreover the dust produces a grey effect in the wavelength range analysed in this work. From the extinction coefficients we use inversion methods to compute the
particle size distribution in both atmospheric conditions. Approximately, the extinction on clear and dusty days is produced by aerosol particles with radius between 40 and 120nm and between 120 and 3000nm, respectively.
%K atmospheric effects - site testing

%R 1998A&AS..129..425C
%J-430
%A Coma J.C., Lara M., Lopez Moratalla T.
%T Uniform approximation of planetary ephemerides.
%M ds6414
%F 1998.04.08
%B DE200/LE200 astronomical ephemerides are compressed finding the "best approximation" in the Chebyshev sense. When reproducing the data base from this polynomial approximation, the maxima and minima values of the error are equal in absolute value over the considered interval. In order to obtain polynomials valid also for a reliable evaluation at points interpolated on the data base, we work with dense data bases: the fact that the estimate of the error provided by the
best approximation of continuous functions is valid for all the interval and the smoothness of the discrete error functions we have obtained guarantee, in our opinion, the desired bound for the error also for interpolated points. Consequently we obtain maximum compression and fast evaluation.
%K ephemerides - planets and satellites