%R 1994A&AS..103..201I
%J-233
%A Ivison R.J., Bode M.F., Meaburn J.
%T An atlas of high resolution line profiles of symbiotic stars. II. Echelle spectroscopy of northern sky objects
%B We present an atlas of high and low resolution Echelle spectra for 35 symbiotic stars visible from the Roque de los Muchachos Observatory, Canary Islands. This represents the northern portion of an all-sky optical survey using two similar Echelle spectrometers. More than half of the systems in our sample exhibit a centrally reversed Balmer H{alpha} line with the minimum displaced blueward of the line centre. This supports the idea that the double-peaked morphology is
 generally the result of absorption in our line of sight by neutral material shed from the late-type component. Our data also support the view that systems with narrow, single-peaked Balmer lines have density-bounded emission nebulae. A significant proportion of the systems observed here have complex forbidden line profiles indicative of high velocity, low density gas. This suggests that currently popular models which describe the emission nebulae purely in terms of radiative
 ionization may need revision. Of the symbiotics for which our atlas covers the 4686 A region, three quarters show the He II line in emission but only a small proportion of the observed lines have appreciable structure. The He^2+^ regions are probably centred on the hot component in each binary but the symmetry of our line profiles may indicate that the dominant contribution to observed He II line flux is removed from this strong source of radiative acceleration and may
 instead lie close to the denser environment of the cool, late-type star. Our main purpose is to provide an atlas for general community use and with this in mind we describe how the data may be accessed using several electronic networks.
%K line: formation - line: profiles - atlases - stars: binaries: symbiotic - stars: novae, cataclysmic variables

%R 1994A&AS..103..235M
%J-344
%A Morgan D.H.
%T The UKST Survey of planetary nebulae in the Large Magellanic Cloud
%B This paper presents a list of 54 planetary nebula candidates in the Large Magellanic Cloud, newly identified on objective prism plates taken with the U.K. 1.2 m Schmidt Telescope. Co-ordinates and finding charts are given. The plates used give full coverage of the LMC thereby allowing completion of the UKST LMC Planetary Nebula Survey. A total of 265 objects were detected in the Survey and their spatial distribution is discussed.
%K Large Magellanic Cloud - planetary nebulae

%R 1994A&AS..103..245M
%J-271
%A Molinari E., Banzi M., Buzzoni A., Chincarini G., Pedrana M.D.
%T Multicolor photometry of clusters of galaxies: A3284, A3305, A1942
%B We present complete multicolor photometry in the Gunn system for
the three clusters of galaxies A3284, A3305 and A1942 at redshift
z~0.2. INVENTORY magnitudes and colours have been obtained for over 1,000 objects in
the three fields down to  g=24,  and with a good completeness level in the 
detections (85% or better) about one magnitude brighter.
By fitting with King profiles the r counts we derived the total number of
galaxies and the core radius down to the r magnitude limit in each cluster.
These are N_TOT_=146 galaxies and R_c_=0.24  Mpc for A3284, N_TOT_=129 
and R_c_=0.20 Mpc for A3305, N_TOT_=130 and R_c_=0.24 Mpc for A1942.
The observed mean redshift of the clusters is z=0.150+/-0.001 for A3284,
 z=0.157+/-0.001 for A3305, and  z=0.226+/-0.001 for A1942.
The c-m diagrams and the g-i colour distribution as well as the two-colour
diagrams are used to single out early-type galaxies and spirals on the basis
of their different photometric properties. This approach aimed at a
self-consistent classification of galaxies on the basis of photometric
indicators will be further developed for a systematic study of the galaxy
population in distant clusters.
%K galaxies: clustering - galaxies: clusters: individual: A1942, A3284, A3305 - galaxies: evolution - galaxies: photometry

%R 1994A&AS..103..273L
%J-277
%A Lennon D.J., Burke V.M.
%T Atomic data from the IRON project. II. Effective collision strength s for infrared transitions in carbon-like ions
%B We present new calculations of cross-sections for the electron impact excitation of carbon-like ions from N II to S XI, paying particular attention to the infrared transitions between the 2p^2^ ^3^P J=0,1,2 ground state fine-structure levels. We also give rate coefficients, assuming a Maxwellian electron velocity distribution, in the form of effective collision strengths for these transitions up to an electron temperature of 10^5^ K. We also give results for transitions
 involving the other 2p^2^ terms (^1^D and ^1^S) as well as the 2s2p^3^ (^5^S) term. The present results are in excellent agreement with a number of similar calulations available in the literature but are more comprehensive in scope.
%K atomic - atomic processes data

%R 1994A&AS..103..279M
%J-291
%A Mallik S.V.
%T The Ca II triplet lines in cool stars
%B Observations of the infrared triplet lines of ionized calcium are presented for 91 stars brighter than m_v_=+7.0 in the spectral range F8-M4 of all luminosity classes and over a range of metallicities [Fe/H] from -0.65 to +0.60. The above spectra have been obtained at a spectral resolution of 0.4 A with a coude echelle spectrograph using the Thomson CCD as the detector. This study has been undertaken primarily to investigate the dependence of the Ca II triplet strengths
 over the broad range of atmospheric parameters like luminosity, temperature and metallicity. The Ca II triplet lines are a powerful diagnostic of the stellar populations in galaxies because of their sensitivity to the above parameters. Our detailed analysis indicates a strong correlation between the equivalent width of the Ca II triplet lines and surface gravity, much stronger in metal rich stars than in metal poor stars. The Ca II equivalent widths are fairly insensitive to
 temperature over the range of luminosity covered. However, they are found to be quite sensitive to metallicity, more conspicuously in supergiants than in giants and dwarfs. Observations are compared with recent theoretical calculations of these lines in NLTE atmospheres.
%K stars: atmospheres - stars: late-type - galaxies: stellar content

%R 1994A&AS..103..293V
%J-300
%A Vela Villahoz E., Sanchez Almeida J., Wittmann A.D.
%T Spectral lines unaffected by instrumental polarization. II. Selected lines of astrophysical interest
%B Lines with no linear polarization induced by Zeeman effect are unaffected by instrumental polarization. We compile 86 such electric dipole lines with differing temperature and magnetic field sensitivities. In addition, we list 420 spectral lines which produce negligible linear polarization. In most cases, this second set can also be regarded as lines unaffected by instrumental polarization.
%K stars magnetic fields - Sun: magnetic fields polarization - techniques: polarimatry

%R 1994A&AS..103..301H
%J-313
%A Hu J.Y., te Lintel Hekkert P., Slijkhuis F., Baas F., Sahai R., Wood P.R.
%T  A systematic study of IRAS selected proto-planetary nebula candidates. II. OH and CO observations
%B  We present OH maser observations of a sample of 62 IRAS-selected
proto-planetary nebula (PPN) candidates, and CO observations of the 29 sources
in this sample which are brighter than 25 Jy in the IRAS 25 {mu}m band.
Sixteen sources have been detected in (J=1-0) or (J=2-1). We observed and
detected two sources in (J=3-2). We have detected sixteen sources
(four of which are CO sources) in the 1612 MHz transition of OH. Half of
these are also detected at 1667 and/or 1665 MHz. The CO and OH spectra are
characteristic of emission from an expanding circumstellar shell, with an
average expansion velocity of ~15 kms. The OH maser sources are not
variable over a period of one to five years, with only a few exceptions.
Several OH sources show multiple components in their spectra,
sometimes strongly circularly polarized. One double-peak OH maser source,
IRAS 20406+2953, shows an enigmatic variability in circular polarization.
%K circumstellar matter - stars; asymptotic, post-asymptotic giant branch (AGB, post-AGB) - radio lines: molecular: circumstellar

%R 1994A&AS..103..315A
%J-320
%A Anupama G.C., Kembhavi A.K., Prabhu T.P., Singh K.P., Bhat P.N.
%T BVRI photometry of the Dipper Asterism region in M 67
%B We present Cousins BVRI magnitudes for stars in the M 67 `dipper asterism' region, based on observations carried out at the prime focus of the 2.3 m Vainu Bappu Telescope of the Vainu Bappu Observatory, Kavalur. The photometric system is calibrated using the photometric standards in the field and linear transformation relations are derived. Photometric results are reported for 37 stars in BVRI bands. Results are also presented for an additional set of 35 stars in only two
 or three of these bands. The photometric accuracy is better than 3% for magnitudes B<16, V,R<17 and I<14, and is slightly poorer for the results presented beyond this limit.
%K clusters: open - clusters: individual: M 67 - CCD photometry - photometric calibration

%R 1994A&AS..103..321N
%J-347
%A North P., Berthet S., Lanz T.
%T The nature of the F str {lambda}4077 stars. V. Spectroscopic data
%B We report first high-resolution spectroscopic observations of 17 stars classified F str {lambda}4077 by Bidelman. They are compared to different types of stars, which have been observed at the same time, including 3 CH subgiants, 3 barium stars, 5 {lambda} Bootis stars, Ap/Am stars, and normal main-sequence stars. The detailed equivalent widths and abundances are given for all measured spectral lines, as well as the mean abundance per species for each object. These data
 and their significance are described in detail and discussed in an article published in the Main Journal.
%K stars: classification, abundances, peculiar A, evolution of, close binaries - nucleosynthesis

%R 1994A&AS..103..349S
%J-363
%A Stickel M., Kuehr H.
%T An update of the optical identification status of the S4 radio source catalogue
%B An update of the optical identification status of the S4 radio source catalogue is presented. An extensive literature search has been made to gather the types of the optical counterparts, their magnitudes and redshifts. As far as possible, references to other optical catalogues are given for these data, which are often supplemented by more detailed notes on individual sources. Accurate radio positions taken from the literature are given for a large fraction of the sources.
%K catalogues - radio continuum: general - BL Lac objects: general - galaxies: general - quasars: general

%R 1994A&AS..103..365B
%J-373
%A Bondi M., Mantovani F., Sherwood W., Tzioumis A., Venturi T.
%T Amplitude calibration of the European VLBI network
%B We present the results from a calibration programme for the European VLBI network (EVN). The suitability of some radio sources as amplitude calibrators for the EVN is investigated. The influence of some station-dependent factors, the use of different correlators and recording systems on the results are also examined. The a-priori calibration at each network telescope has been assessed. We find that the station a-priori calibration could be greatly improved and that
 calibrator sources should be included in each full track VLBI observation. The suitability of some sources as calibrators, with particular emphasis on the radio source OQ208, is also discussed.
%K methods: data analysis - galaxies: OQ 208 (\object{Mrk 668}) - techniques: interferometric

%R 1994A&AS..103..375C
%J-389
%A Carraro G., Chiosi C., Bressan A., Bertelli G.
%T Five old open clusters: NGC 2682, NGC 2243, Berkeley 39, NGC 188 and NGC 6791
%B The color-magnitude diagrams (CMD) of five old open clusters, namely NGC 2682, NGC 2243, Berkeley 39, NGC 188, and NGC 6791 are examined in detail with the aid of the synthetic color-magnitude diagram technique described by Carraro et al. (1993), and the color excess E_B-V_, distance modulus (m-M), and age of each cluster are derived. The goal is to provide an homogeneous ranking of the cluster ages. The analysis is made using two types of stellar models in which
 different prescriptions are adopted for the extension of the convective cores, i.e. either the classical or the overshoot scheme. The stellar models in use are from Alongi et al. (1993), Bressan et al. (1993), and Fagotto et al. (1993a,b). The evolutionary tracks go from the main sequence up to the start of the thermally pulsing regime of the asymptotic giant branch (TP-AGB) phase. The purpose is to discriminate between the two evolutionary scenarios. It turns out that all
 the clusters have turn-off masses either slightly greater or equal to the value of 1.1 M_{sun}_, at which we expect the transition from convective to radiative core H-burning to occur. As far as the mixing mechanism is concerned, the results are not very conclusive. For the youngest clusters of our sample, namely NGC 2682 and NGC 2243, models with convective overshoot seem to provide a slightly better fit of the observed CMD and luminosity function. For the oldest cluster
 of our sample, namely NGC 6791 with age of 8 Gyr, there is no appreciable difference passing from one scheme to another. Finally, for the remaining clusters, namely Berkeley 39 and NGC 188, the situation is ambiguous. This trend is not surprising, because we expect the convective core and hence associated overshoot to vanish at decreasing turn-off mass and hence increasing age. As expected the ages derived from overshoot models are slightly older than those obtained
 from standard models. The five clusters on consideration can be ranked as function of the age as follows (the first value refers to classical models, the second one to models with overshoot): NGC 2682 (4.3 Gyr and 4.8 Gyr), NGC 2243 (3.5 Gyr and 3.9 Gyr), Berkeley 39, (6.0 Gyr and 6.5 Gyr), and NGC 188 (7.0 Gyr and 7.5 Gyr). No age difference is found in the case of NGC 6791 for which both types of stellar models yield 8.0 Gyr.
%K open clusters and associations - stars: evolution - stars: interiors