%R 1997A&AS..122..399P
%J-407
%A Poggianti B.M.
%T K and evolutionary corrections from UV to IR.
%M ds1082
%F 1997.04.16
%B K and evolutionary corrections are given for the E, Sa and Sc Hubble types for the U, B, V, R, I, J, H, K filters of the Johnson-Bessell & Brett photometric system and the gri filters of the modified Thuan & Gunn system up to the redshift z=3. Their dependence on the time scale of star formation in ellipticals is investigated.
The corrections are computed according to an evolutionary synthesis model that reproduces the integrated galaxy spectrum in the range 1000-25000{AA}; such a model makes use of an infrared observed stellar library and its results are compared with nearby galaxies. Evolving spectral energy distributions of the various Hubble types, as well as optical-IR and IR-IR colour evolution and adopted filter response functions are also given.
%K galaxies: evolution - galaxies: photometry - galaxies: distances and redshifts - galaxies: fundamental parameters - cosmology: miscellaneous

%R 1997A&AS..122..409L
%J-414
%A Lobo C., Biviano A., Durret F., Gerbal D., Le Fevre O., Mazure A., Slezak E.
%T A photometric catalogue of the Coma cluster core.
%M ds1232
%F 1997.04.16
%B We have obtained a mosaic of CCD images of the Coma cluster in the V-band covering a region of approximately 0.4{deg}^2^ around both central cluster galaxies NGC 4889 and NGC 4874. An additional frame of ~ 90arcmin^2^ was taken of the south-west region around NGC 4839. We derived a catalogue of 7023 galaxies and 4096 stars containing positions, central surface brightnesses and isophotal V_26.5_ magnitudes. We estimate that data is complete up to V_26.5_~22.5 and the
surface brightness limiting detection value is {mu}~24mag/arcsec^2^. In this paper we present the catalogue (available in electronic form alone), along with a detailed description of the steps concerning the data reduction and quality of the computed parameters.
%K galaxies: clusters: individual: Coma cluster - galaxies: photometry - galaxies: luminosity function

%R 1997A&AS..122..415D
%J-432
%A de Laverny P., Geoffray H., Jorda L., Kopp M.
%T Long-term UBV(RI)_c_ monitoring of 12 southern hemisphere Long Period Variables.
%M ds1183
%F 1997.04.16
%B A program of UBV(RI)_c_ photometric observations of twelve southern hemisphere Long Period Variables (LPV or Miras) has been carried out at the European Southern Observatory. Each star was observed on at least 11 occasions up to 29 over a 4-year period. A determination of their spectral types from the (V-R_c_) and (R_c_-I_c_) colours was also performed using the method described by Celis (1986AJ.....91..405C). We therefore present for the first time spectral type variations together
with visible and colour light-curves for at least three successive cycles. New photometric parameters as visible and spectral type extrema are given. Spectral type variations are found in the range 1.3-4.5 subclasses. The variations during a cycle and from cycle-to-cycle are discussed and short-term declines with large amplitude are reported for R Oct and RY Hyi. We finally estimate the distance of these stars using a (M_V_^max^, P, Spectral type) relation. It is shown that
rather good distances (mean error less than 30%) can be determined if the period of the stars is known and good UBVRI data are collected at the maximum of luminosity.
%K stars: late-type - stars: AGB and post-AGB - stars: variables - stars: distances

%R 1997A&AS..122..433T
%J-440
%A Tucholke H.-J., Brosche P., Odenkirchen M.
%T The Bonn contribution to the extragalactic link of the Hipparcos proper motion system.
%M ds5528
%F 1997.04.16
%B In order to calibrate the proper motions of the Hipparcos astrometry satellite, our group has measured accurate absolute proper motions of Hipparcos stars in small fields around optically bright extragalactic radio sources or bright galaxies with star-like features. In addition, we also use fields where relative proper motions are calibrated by measurements of large numbers of stars and galaxies on wide-field plates. The median internal accuracy of our relative proper
motions, based on photographic plates with epoch differences up to 100-years (typically 70-years), is 1.0-milliarcsec/year (mas/a), while the calibration to an inertial system in each of the 13 fields has a median uncertainty of 1.3mas/a. We compute the rotation from the Hipparcos proper motions (median internal errors 0.9mas/a) to the extragalactic reference frame represented by our absolute proper motions, using 88 stars in common. The three components of the angular
elocity vector have internal errors of 0.3mas/a. Our rotation solution has been used together with those of independent groups for the extragalactic calibration of the Hipparcos proper motion system (Kovalevsky et al. 1996, A&A, submitted). It compares favourably with the adopted mean solution.
%K reference systems - astrometry - quasars: general - BL Lac objects: general

%R 1997A&AS..122..441C
%J-445
%A Costa E., Loyola P.
%T Optical astrometry of Benchmark radio sources. IV. New results in the southern hemisphere.
%M ds1247
%F 1997.04.16
%B Optical positions relative to the International Reference Stars Catalogue (IRS), and therefore in the system of the FK5, have been obtained for the optical counterparts of 40 compact extragalactic radio sources south of {delta}~+6{deg}. Many of these sources are being considered as possible Benchmark objects for the establishment of a quasi-inertial unified radio/optical reference frame. Precision levels as good as 0.1" in both coordinates were achieved. A comparison with
VLBI radio positions available for these sources is presented. We give new evidence for the existence of an offset in the origin of right ascension between the radio and optical reference frames as defined at present.
%K astrometry - reference systems

%R 1997A&AS..122..447W
%J-461
%A Wroblewski H., Torres C.
%T New proper-motion stars with declination between -5{deg} and -30{deg} and right ascension between 9h and 13h 30m.
%M ds1174
%F 1997.04.16
%B Data are given for 492 new stars with proper motion larger than 0.15 arcsec/year found on 21 areas covering 25 square degrees each. These are located between -5{deg} and -30{deg} in declination and between 9h and 13h30m in right ascension. Photographic magnitudes range from 9.5 to 18.5. Four stars have proper motions larger than 0.5arcsec/year, in a magnitude range between 15.5 and 17.5.
%K astrometry - stars: kinematics - Galaxy: halo

%R 1997A&AS..122..463K
%J-470
%A Kunkel W.E., Irwin M.J., Demers S.
%T Carbon stars in the halo of the Magellanic Clouds: Identification and radial velocity data.
%M ds1151
%F 1997.04.16
%B We present the current status of our ongoing cool carbon star survey in the halo of the Magellanic Clouds. Candidate cool carbon stars were identified from APM measures of pairs of UK Schmidt Telescope B_J_ and R survey plates. Intermediate resolution spectroscopy on the duPont Telescope, Las Campanas, was used to simultaneously verify the nature of the candidates, late M-type giants or AGB carbon stars, and to derive their radial velocity. Coordinates, finding charts and
radial velocity data for 392 spectroscopically identified cool carbon stars distributed out to angular distances of 10 degrees from the Cloud optical centres are given. Radial velocities were also obtained for 133 known carbon stars in the Large Magellanic Cloud, in the inter-Cloud region, in the wing of the Small Magellanic Cloud and in a few SMC star clusters. These intermediate-age carbon stars define ideal kinematic test particles to investigate recent dynamical
interactions between the Galaxy-LMC-SMC system and in particular the origin of the morphological disturbances seen in the SMC and parts of the LMC, the origin of the Magellanic Stream and the total mass of the LMC.
%K galaxies: Magellanic Clouds - stars: carbon - technique: radial velocities

%R 1997A&AS..122..471K
%J-481
%A Kaluzny J., Kubiak M., Szymanski M., Udalski A., Krzeminski W., Mateo M., Stanek K.
%T The optical gravitational lensing experiment. Variable stars in globular clusters. II. Fields 5139D-F in {omega} Centauri.
%M ds5198
%F 1997.04.16
%B Three fields located close to the center of the globular cluster {omega} Cen were surveyed in a search for variable stars. We present V-band light curves for 32 periodic variables. This sample includes 10 SX Phe stars, 19 eclipsing binaries, and three likely spotted variables (FK Com or RS CVn type stars). Only 5 of these variables were previously known (including two objects reported in Paper I). All SX Phe stars and 8 eclipsing binaries from our sample belong to blue
stragglers. Five binaries occupy positions on the upper main-sequence of the cluster and another four are located at the base of the subgiant branch. Of particular interest is detection of a detached binary system with a period P=4.64 day. Further study of this star can provide direct information about properties of turnoff stars in {omega} Cen. All SX Phe stars and most of eclipsing binaries discovered in our survey are likely cluster members. We present V vs. V-I
color-magnitude diagrams for the monitored fields. A populous group of likely hot subdwarfs as well as numerous candidates for blue stragglers can be noted in these diagrams. Our data indicate that {omega} Cen possesses the largest number of blue stragglers among all galactic globulars.
%K globular clusters: individual: {omega} Cen - star: variables: other - blue stragglers - binaries: eclipsing - HR diagram

%R 1997A&AS..122..483B
%J-488
%A Barbuy B., Ortolani S., Bica E.
%T NTT V, I, z photometry of the metal-rich bulge globular cluster Terzan 6.
%M ms5458
%F 1997.04.16
%B We present for the first time optical (V, I and Gunn z) colour magnitude diagrams for Terzan 6, which were collected under excellent seeing conditions with the ESO NTT telescope. The horizontal branch morphology is red, nearly superimposed on the red giant branch. The red giant branch morphology presents characteristics intermediate between those of 47 Tuc and NGC 6528/NGC 6553. We derive a reddening of E(B-V)=2.24 and a distance d_{sun}_=7.0kpc (assuming R=3.1). We
conclude that Terzan 6 belongs to the metal-rich bulge globular cluster system.
%K globular clusters: individual: Terzan 6 ; general - HR diagram

%R 1997A&AS..122..489G
%J-494
%A Guglielmo F., Epchtein N., Arditti F., Sevre F.
%T New infrared carbon stars in the IRAS point source catalog.
%M ds5407
%F 1997.04.16
%B We present new results of a search for infrared carbon stars (IRCS) based on the combination of IRAS and near infrared colours. A sample of 207 stars with IRAS colours that characterize IRCS is selected and measured in the JHKL photometric bands. Using a [12-25] vs. K-L colour diagram, 20 new IRCS candidates are proposed. Medium resolution spectra in the ~6000-9000{AA} range of 8 of these candidates confirm their carbon rich nature. In addition we propose a few stars
with LRS class "4n" as oxygen-rich candidates, and a few stars with LRS classes "0n" and "1n" as carbon-rich.
%K stars: carbon - stars: late-type - stars: AGB and Post-AGB - galaxy: stellar content - infrared: stars - stars: circumstellar matter

%R 1997A&AS..122..495M
%J-505
%A Munari U., Zwitter T., Bragaglia A.
%T CCD spectrophotometry of CVs. IV. 3430-7850 {AA} atlas for 27 faint systems.
%M ds1271
%F 1997.04.16
%B CCD fluxed spectra are presented for 27 objects from the Downes & Shara (1993PASP..105..127D) catalogue of Cataclysmic Variables (CVs). The stars have been selected among those listed as lacking published spectra. As for previous papers in this series, the aim is to check the CV status of the objects and to provide spectrophotometric data over a wide wavelength range. Integrated BVR_C_ magnitudes, continuum fluxes at selected wavelengths and integrated fluxes of emission lines are
derived for the programme stars. Among the 27 programme stars, 18 show a spectrum supporting the CV classification.
%K Novae: cataclysmic variables - white dwarfs

%R 1997A&AS..122..507H
%J-513
%A Hatzidimitriou D., Croke B.F., Morgan D.H., Cannon R.D.
%T Kinematics of carbon stars in the outer regions of the Small Magellanic Cloud.
%M ds4809
%F 1997.04.16
%B We present a radial velocity survey of a sample of the field population of carbon stars in the outer parts of the Small Magellanic Cloud (SMC). This first set of results includes radial velocities for 71 carbon stars, with an individual precision of +/-2-5km/s. The mean heliocentric velocity of the stars (excluding one very high velocity star) is 149.3+/-3.0km/s with a velocity dispersion of 25.2+/-2.1km/s. These values drop to 145.5+/-2.7km/s and 20.6+/-1.9km/s
respectively, if we exclude the stars belonging to the Outer Wing. The velocity distribution does not show the multiple peaks seen in some samples of Population I objects. The mass of the SMC as inferred from the above velocity dispersion (without the outer Wing stars) is =~1.2x10^9^M_{sun}_.
%K stars: carbon stars - galaxies: kinematics - Magellanic clouds

%R 1997A&AS..122..515Z
%J-519
%A Zhang R.X., Fang M.J., Zhai D.S.
%T HL Aurigae: A near-contact binary system.
%M ds1204
%F 1997.04.16
%B Photoelectric observations of HL Aur were carried out with the 60cm reflector of Beijing Astronomical Observatory in 1990 and 1994, and the first photoelectric BV light curves were obtained along with a newly derived ephemeris. The period of the system appears to be constant over the past 65-years. Using the Wilson-Devinney program a photometric analysis of the B and V light curves is performed. It is evident that HL Aur is a near-contact binary with a mass ratio of
q=m_2_/m_1_=0.722+/-0.011. The primary component of the system is essentially in contact with its Roche lobe, while the secondary is detached but nearly in contact with its lobe. It is found that the components of the system are slightly evolved and located near the terminal-age main sequence. The binary is consistent with the general evolutionary picture for near-contact systems.
%K stars: individual: HL Aur - binaries: eclipsing

%R 1997A&AS..122..521S
%J-528
%A Simien F., Prugniel P.
%T Kinematical data on early-type galaxies. I.
%M ds1216
%F 1997.04.16
%B As part of an ongoing program on the main parameters of early-type galaxies, we have performed long-slit absorption spectroscopy on a sample of 21 ellipticals and S0s. We present determinations of the central velocity dispersion and, for 18 objects, velocity-dispersion profiles and rotation curves.
%K galaxies: elliptical & lenticular, cD - galaxies: kinematics and dynamics - galaxies: fundamental parameters

%R 1997A&AS..122..529W
%J-532
%A Walter H.G., Hering R., de Vegt C.
%T Radio stars for linking celestial reference frames.
%M ds1273
%F 1997.04.16
%B Radio stars play a key role in establishing the link between optical reference frames and the conventional celestial reference frame based on extragalactic radio sources. The relevant astrometric, astrophysical and radio quantities are compiled of 66 cardinal radio stars currently suited to frame connection and maintenance of the link. The catalogue entries are supplied with ample bibliographical codes and annotations for easy data retrieval.
%K catalogues - astrometry - reference frames - radio continuum: stars

%R 1997A&AS..122..533D
%J-534
%A Dimitrijevic M.S., Sahal-Brechot S.
%T Stark broadening of spectral lines of multicharged ions of astrophysical interest. XV. P IV spectral lines.
%M ds1269
%F 1997.04.16
%B Using a semiclassical approach, we have calculated electron-, proton-, and He III-impact line widths and shifts for 114 P IV multiplets for perturber densities 10^15^-10^20^cm^-3^ and temperatures T=5000-1000000K. The obtained results have been compared with results obtained by using various simpler approaches.
%K lines: profile-atomic data

%R 1997A&AS..122..535L
%J-545
%A Lay O.P.
%T The temporal power spectrum of atmospheric fluctuations due to water vapor.
%M ds1227
%F 1997.04.16
%B Irregular variations in the refractivity of the atmosphere cause fluctuations in the phase measured by interferometers, limiting the spatial resolution that can be obtained. For frequencies up to the far infrared, water vapor is the dominant cause of the variations. The temporal power spectrum of the phase fluctuations is needed to assess correction schemes such as phase referencing using a nearby calibrator and water vapor radiometry. A model is developed for the temporal
power spectrum of phase fluctuations measured by an interferometer through a layer of Kolmogorov turbulence of arbitrary thickness. It is found that both the orientation of the baseline with respect to the wind direction and the elevation of the observations can have a large effect on the temporal power spectrum. Plots of the spectral density distribution, where the area under the curve is proportional to phase power, show that substantial contributions from length scales as
long as 100 times the interferometer baseline are possible. The model is generally consistent with data from the 12-GHz phase monitor at the Owens Valley Radio Observatory, and allows the data to be extrapolated to an arbitrary baseline, observing frequency and elevation. There is some evidence that there can be more than one component of turbulence present at a given time for the Owens Valley. The validity of the frozen turbulence assumption and the geometrical optics
approximation is discussed and found to be reasonable under most conditions. The models and data presented here form the basis of an analysis of phase calibration and water vapor radiometry (Lay 1997A&AS..122..547L).
%K atmospheric effects - instrumentation: interferometers - site testing - techniques: interferometric

%R 1997A&AS..122..547L
%J-557
%A Lay O.P.
%T Phase calibration and water vapor radiometry for millimeter-wave arrays.
%M ds1229
%F 1997.04.16
%B Correcting for the fluctuations in atmospheric path length caused by water vapor is a major challenge facing millimeter- and submillimeter-wave interferometers, and one that must be overcome to obtain routine sub-arcsecond resolution. Using the model for the power spectrum of phase fluctuations developed in Lay (1997A&AS..122..535L), the existing technique of phase referencing to a bright calibrator object is analysed. It is shown that the phase errors after calibration have comparable
contributions from both the target and calibrator measurements. The technique of water vapor radiometry, where the amount of emission from water vapor in the beam of each antenna is used to estimate a path correction, is also examined. It is found that there are two levels on which a correction can be made. The simplest corrects just the fluctuations within each on-source period; the calibration requirements for the radiometers are modest, and this partial correction can give
a substantial improvement in the resolution and coherence time of an interferometer. The atmospheric fluctuations on longer timescales remain uncorrected, however, and are significant. To remove these, a full correction is required, which measures the change in the path difference that occurs when moving between the calibrator and the target, in addition to the on-source fluctuations. Since there can be a large difference in airmass between the calibrator and the target,
measuring this change requires that the radiometers have the same response to a given column of water vapor to within ~0.1%. Two possible methods of achieving this very stringent limit are outlined. For reasonable observing conditions at 230 GHz, it is predicted that the effective atmospheric "seeing" (the apparent smearing of the sky brightness distribution due to the atmosphere) is improved from 0.6" (phase referencing every 25 minutes) to 0.3" (phase referencing and
partial radiometric correction). A full radiometric correction would, in principle, restore perfect seeing.
%K atmospheric effects - instrumentation: interferometers - site testing - techniques: interferometric

%R 1997A&AS..122..559C
%J-569
%A Clausen J.V., Larsen J.M., Garcia S.S., Gimenez A., Storm J.
%T Secondary standard stars for uvby {beta} CCD photometry.
%M ds5468
%F 1997.04.16
%B Accurate standard uvby indices are presented for 73 southern B, A, F and G stars in the V magnitude range 8.2 to 10.9. They cover all three transformation regions of the uvby system (Olsen 1983A&AS...54...55O) well. Standard {beta} indices are included for the 55 B, A, and F stars in the sample. Our results provide a useful set of secondary standards for uvby {beta} CCD photometry with southern hemisphere 1-2 m class telescopes. A critical comparison with published photometry, in general
based on fewer observations, is given.
%K Stroemgren photometry - astronomical data bases: miscellaneous - stars: fundamental parameters - stars: general

%R 1997A&AS..122..571M
%J-580
%A Martin C., Mignard F., Froeschle M.
%T Mass determination of astrometric binaries with Hipparcos. I. Theory and simulation.
%M ds5363
%F 1997.04.16
%B The analysis of the observations of double stars made by the ESA satellite Hipparcos has involved a very specific processing to derive the relevant astrometric parameters. This required to distinguish between several categories of double stars according to the separation and orbital motion. We show that for close pairs with orbital period less than about 20-years, the concept of photocentric orbit of an astrometric binary needs to be generalized to benefit fully from the
accuracy of Hipparcos. We introduce a point more naturally associated with the Hipparcos observations, the hippacentre, whose orbital path is not longer similar to the relative keplerian orbit of the components, unlike that of the photocentre. For systems with separation larger than about 0.3", it is possible to determine separately the mass and the intensity ratio of the components from the absolute path of the hippacentre on the sky. For smaller separations the scale of the
photocentric orbit is recovered as a limiting case. The scope of this paper is to set forth the principles of the method and to explore its possibilities and limitations from extensive simulations.
%K methods: data analysis - binaries: visual - stars: fundamental parameters

%R 1997A&AS..122..581H
%J-584
%A Hadrava P.
%T Relative line photometry of eclipsing binaries.
%M ds5530
%F 1997.04.16
%B A new method of "line-photometry" using the changes of line intensities for determination of light curves in eclipsing binaries is described. This method is based on a generalization of the method of spectrum decomposition by Fourier transform performed by the code KOREL for spectrum disentangling.
%K line profiles - stars: binaries spectroscopic - methods: numerical

%R 1997A&AS..122..585B
%J-592
%A Betta R., Peres G., Reale F., Serio S.
%T An adaptive grid code for high resolution 1-D hydrodynamics of the solar and stellar transition region and corona.
%M ds5174
%F 1997.04.16
%B We present a new version of the Palermo-Harvard hydrodynamic model of plasma confined in coronal loops, based on a regridding algorithm which ensures limited variations of thermodynamical variables across grid points. The code provides an accurate description of the dynamics of the chromosphere-corona transition region, in spite of the very steep temperature and density gradients, even during flare-like transients. The new model can be used to synthesize, together with
X-ray emission, the optically thin emission originating from the transition region, mainly in the EUV band. Here we show sample results.
%K methods numerical - hydrodynamics - Sun: transition region - Sun: corona - Sun: flares - Sun: UV radiation