%R 1996A&AS..118..397K
%J-405
%A Kerschbaum F., Lazaro C., Habison P.
%T Irregular variables of type Lb. New JHKL'M-photometry for 160 stars.
%F 1996.08.05
%B This paper presents new near infrared observations of 160 Irregular variables of type Lb in the JHKL'M filter bands. These measurements are supplemented by data for additional 56 stars taken from the literature. In total 220 datasets are available because of some multiple observations. From our sample, 216 stars have near infrared (NIR) photometry now. Our sample of visually bright Lb-variables displays very similar infrared properties when compared with SRa- and
SRb-variables. Derived from NIR-two colour diagrams the oxygen-rich Lbs seem to have intermediate atmospheric conditions between Miras and normal giants. There may be a sligthly larger "contamination" with non AGB-giants than in the case of the semiregulars. Using only our IR-colours the S- and the Carbon-stars among the Lbs again are undistinguishable from SR-variables of the same chemistry.
%K stars: asymptotic giant branch (AGB) - stars: variables - stars: mass-loss - infrared: stars

%R 1996A&AS..118..407N
%J-420
%A Nordstroem B., Andersen J., Andersen M.I.
%T Critical tests of stellar evolution in open clusters. I. New photometry and radial velocities for NGC 3680.
%F 1996.08.05
%B We present new CCD photometry in the b and y colours of the Stroemgren uvby system for 310 stars in a 13'x13' field centered on the intermediate-age open cluster NGC 3680. Careful cross-checks indicate that previously published BV photometry of NGC 3680 is affected by random and/or systematic errors precluding its use in critical comparison with theoretical isochrone computations. Detailed notes on several individual stars are given. In addition, we present =~400 new
photoelectric radial-velocity observations of 109 stars obtained with the CORAVEL scanner during the period 1988-1994. These data allow substantially complete identification of member and non-member stars in the field, and of spectroscopic binaries in both groups. Rotational velocities have also been derived for the programme stars, and our velocity variability criteria for stars of all rotations are described. The further astrophysical discussion of the data, including the
definition of radial-velocity membership criteria, theoretical isochrone fitting, and the dynamical state of the cluster and the origin of its "bimodal turnoff", will appear in a separate paper (Nordstroem et al. 1996).
%K stars: evolution - stars: fundamental parameters - stars: HR diagram - stars: kinematics - open clusters and associations: individual: NGC 3680

%R 1996A&AS..118..421S
%J-428
%A Simon V.
%T The peculiar interacting binary V Sagittae: Brightness variations in 1932-1994.
%F 1996.08.05
%B The analysis of the historical light curve revealed several kinds of variations not connected with the orbital modulation: a) large outbursts consisting of a primary (amplitude about 2mag_ vis._) and a fainter secondary peak; b) transitions from the high to the low state and vice versa; c) small outbursts (amplitude about 0.7mag_vis._) on the time scale of 15-20 days in the high state; d) year-to-year variations of brightness. It is shown that drastic changes of the
photometric activity occurred in the course of the last six decades. An interpretation of this activity in terms of mass transfer events in a strongly interacting binary containing an accreting white dwarf is offered.
%K stars: binaries: general - stars: emission-line, Be - novae, cataclysmic variables - stars: variables: other - circumstellar matter - stars: individual: \object{V Sge}

%R 1996A&AS..118..429B
%J-439
%A Bettoni D., Fasano G.
%T Morphology of early-type galaxies in compact groups. IV. Rose groups.
%F 1996.08.05
%B In the previous papers of this series (Bettoni & Fasano 1993AJ....105.1291B, 1995AJ....109...32B and 
Fasano & Bettoni 1994AJ....107.1649F) we presented data relative to early-type galaxies in several 
Hickson (1982ApJ...255..382H; catalog <VII/85>) and Shakhbazyan (1973-1979) Compact Groups. 
In this paper we present, for the first time, data on early-type galaxies belonging to 9 Rose (1977ApJ...211..311R) compact groups. The selection criteria of these groups make them more compact than the Hickson and Shakhbazyan groups and, for this reason, the Rose groups
constitute a good sample for testing the properties of early-type galaxies in environments of extreme (at least apparent) density. Even if the present sample is not a sizeable one (18 objects), we find that morphological and photometric properties of E and S0 galaxies in the Rose groups are fairly consistent with those of galaxies in the Hickson and Shakhbazyan samples. In particular, there is a lack of very flat objects in the ellipticity distribution.
%K galaxies: compact

%R 1996A&AS..118..441S
%J-451
%A Schroeder A., Visvanathan N.
%T New aperture photometry for 217 galaxies in the Virgo and Fornax clusters.
%F 1996.08.05
%B We present photo electric multi-aperture photometry in UBVRI of 171 and 46 galaxies in the Virgo and Fornax clusters, respectively. Many of the galaxies have not been observed in at least one of these passbands before. We discuss the reduction and transformation into the Cousins photometric system as well as the extinction coefficients obtained between 1990 and 1993.
%K galaxies, photometry - galaxies, clusters: Virgo (\object{H 1228+125}), Fornax (\object{ACO S 373})

%R 1996A&AS..118..453L
%J-459
%A Liu Q., Soonthornthum B., Yang Y., Gu S., Niparugs S., Aniwat Sooksawat M.L., Wang B. , Naksata M.
%T BL Eridani: An unstable W Ursae Majoris system with spotted components.
%F 1996.08.05
%B New complete BV light curves of BL Eri are presented. Light-curve variability and asymmetry are seen in both B and V bands, and the observed times of light minimum indicate period changes. The light curves have been analyzed by using the light-curve-synthesis method. Our photometric solution reveals that BL Eri is a contact binary with a common convective envelope. An examination of the available photometric and spectroscopic data indicates that the light-curve variability
may be due to changes of the component radii and the light-curve asymmetry may be consistent with starspot activity on one or both components.
%K stars: binaries: close binaries: individual: \object{BL Eri}

%R 1996A&AS..118..461F
%J-479
%A Friedli D., Wozniak H., Rieke M., Martinet L., Bratschi P.
%T Disc galaxies with multiple triaxial structures. II. JHK surface photometry and numerical simulations.
%F 1996.08.05
%B We present detailed JHK surface photometry with ellipse fits of 13 galaxies selected from previous optical observations as likely candidates for having a secondary bar or a triaxial bulge within the primary bar. We have found 7 double-barred galaxies, 3 double-barred galaxies with an additional intermediate structure with twisted isophotes, and 3 galaxies with a bar and central twisted isophotes. A global analysis of the structural parameter characteristics in the I- and
K-bands is presented. Various numerical models of galaxies with bars within bars are also analysed using the ellipse fitting technique and compared to the observations. A thorough review of the possible hypotheses able to explain this phenomenon is given with emphasis on the most likely ones.
%K galaxies: photometry - galaxies: structure - galaxies: fundamental parameters - galaxies: nuclei - galaxies: evolution

%R 1996A&AS..118..481B
%J-494
%A Berghoefer T.W., Schmitt J.H.M.M., Cassinelli J.P.
%T The ROSAT all-sky survey catalogue of optically bright OB-type stars.
%F 1996.08.05
%B For the detailed statistical analysis of the X-ray emission of hot stars we selected all stars of spectral type O and B listed in the Yale Bright Star Catalogue and searched for them in the ROSAT All-Sky Survey. In this paper we describe the selection and preparation of the data and present a compilation of the derived X-ray data for a complete sample of bright OB stars.
%K stars: early-type - X-rays: stars

%R 1996A&AS..118..495A
%J-502
%A Andrillat Y., Jaschek M., Jaschek C.
%T B[e] stars. II. MWC 349A.
%F 1996.08.05
%B We analyse spectroscopic CCD material obtained at the Haute Provence Observatory. We provide line identifications and equivalent width measurements in the wavelength region 3700-8790A. Over 300 emission features are identified and a comparison of our results with those of other authors is provided, as well as a table of all elements which have been identified in the spectrum of the object. The pattern of elements present is analogous to that of B-type stars, but some
exceptions are noted, such as the absence of C, Al and Mn. We review the present knowledge of the spectrum variability of MWC 349A. The observations indicate that the equivalent widths of the lines of many elements vary by factors of up to two. We also provide a list of diffuse interstellar features observed. The latter lead to an average (B-V) excess of about two magnitudes, which is less than what is expected for an object having an interstellar extinction of 10-11
magnitudes.
%K stars: emission line, B[e] - stars variables: others - stars: individual: MWC 349A

%R 1996A&AS..118..503T
%J-515
%A Tian K.P., van Leeuwen F., Zhao J.L., Su C.G.
%T Proper motions of stars in the region of the Orion Nebula cluster (C 0532-054).
%F 1996.08.05
%B Relative proper motions and membership probabilities for 333 stars within an area of 1.6deg by 1.8deg centred on the Orion Nebula M 42 are determined using plates taken over a period of 83 years with the double astrograph of Shanghai Observatory (scale of 30"/mm). The plates were measured with the ASTROSCAN automatic plate-measuring machine of Leiden Observatory. The average proper motion accuracy obtained for stars in the photographic magnitude range 7 to 14 is 0.3mas/yr.
Errors are somewhat larger towards fainter and brighter magnitude, but the majority lie well below 1mas/yr. 64% of the stars have been measured successfully on at least 13 out of 18 plates. The number of stars with membership probabilities higher than 0.7 is 184. It is shown by a detailed discussion that the proper motions and membership probabilities of the stars determined in this paper are in good agreement with the results presented recently by other authors.
Although there is a clear concentration in the proper motion diagram, both the remaining dispersion of the internal motions and the distribution of "members" as projected on the sky indicate that the stars in this region are not bound as one system, but do have a common origin. A similar conclusion can be drawn from a comparison with spectroscopic and radial velocity data.
%K open clusters - open clusters: individual: C 0532-054 - astrometry

%R 1996A&AS..118..517L
%J-524
%A Labeyrie A.
%T Resolved imaging of extra-solar planets with future 10-100km optical interferometric arrays.
%F 1996.08.05
%B In the recent years, interferometric arrays of optical telescopes have reached sizes of the order of 100 m, but they have yet to produce high-resolution images. The analysis of image formation now shows that such images are theoretically obtainable directly in the recombined focal plane, if there are enough telescopes. Resolved images of extra-solar planets are in principle obtainable with 10 km ground-based arrays.
%K techniques: interferometric planetary systems

%R 1996A&AS..118..525M
%J-528
%A Martin V.A.F., Boczko R., Benevides-Soares P., Leister N.V.
%T Systeme de reference stellaire : effets systematiques. Stellar reference system: Systematic effects.
%F 1996.08.05
%B We discuss two different ways to determine the systematic effects on the star's observations obtained with the astrolabe. The first one is related to the absolute determination of the declinations got through stars belonging simultaneously to 30deg and 45deg zenith distance programmes. The absolute declinations were obtained from a global reduction including all the data. The second way uses a sum of chosen functions, added to the observational results in zenith distance
obtained with astrolabes, which represent both the systematic differences {DELTA}{alpha} and {DELTA}{delta} between catalogues of stars and the instrumental effects {DELTA}I. With this method it is possible to associate several different catalogues as only one. The interest is that it allows the utilization of even single passage stars to get systematic differences {DELTA}{alpha} and {DELTA}{delta}, what is not possible in classical procedure of astrolabe data reduction.
%K astrometry - reference systems - catalogues - instrumentation: miscellaneous

%R 1996A&AS..118..529P
%J-544
%A Piters A.J.M., Groot P.J., van Paradijs J.
%T A combined Fourier-Bessel transformation method to derive accurate rotational velocities.
%F 1996.08.05
%B We describe in some detail the characteristics of a combined Fourier-Bessel transformation technique to derive projected equatorial rotational velocities from spectral line profiles. This technique shares with the Fourier-transformation method, developed by Gray, that it distinguishes rotational broadening of a spectral line from broadening by other mechanisms. The range of rotational velocity values that can be derived with this method is limited mainly by the spectral
resolution (low velocities) and by line blending and the signal-to-noise ratio (high velocities). We discuss the uncertainty on the outcoming rotational velocity as a result of various effects, such as limb-darkening, spectral resolution, noise, data-preparation, and intrinsic broadening. We conclude that the Fourier-Bessel transformation method can provide rotational velocities , with a typical uncertainty down to a few percent. It does not include any modelling of
individual stars with effects as anisotropic macroturbulence included and therefore is less suited for a detailed analysis of individual stars. It is suited for statistical investigation of a large sample of stars.
%K methods: data analysis - methods: numerical

%R 1996A&AS..118..545G
%J-555
%A Groot P.J., Piters A.J.M., van Paradijs J.
%T Rotational velocities of F dwarfs; application of the Fourier-Bessel transformation method.
%F 1996.08.05
%B Projected rotational velocities are presented for 178 bright dwarf stars (V<7) with spectral types in the range A8 till G2. These rotational velocities have been determined by Fourier-Bessel transformation of the line profiles of six Fe I absorption lines in a 50 A wide range centered on 6250A. Rotational velocities of stars with suspected velocities of more than 40km/s were also determined by fitting the whole spectral range with a profile of a slowly rotating star of
the same spectral type that has been convolved with a rotation profile. The agreement between the results obtained with these two methods is very good.
%K line: profiles - stars: rotation - techniques: spectroscopic

%R 1996A&AS..118..557D
%J-573
%A de Jong R.S.
%T Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. II. A two-dimensional method to determine bulge and disk parameters.
%F 1996.08.05
%B In this Paper I present a new two-dimensional decomposition technique, which models the surface photometry of a galaxy with an exponential light profile for both bulge and disk and, when necessary, with a Freeman bar. The new technique was tested for systematic errors on both artificial and real data and compared with widely used one-dimensional decomposition techniques, where the luminosity profile of the galaxy is used. The comparisons indicate that a decomposition of
the two-dimensional image of the galaxy with an exponential light profile for both bulge and disk yields the most reproducible and representative bulge and disk parameters. An extensive error analysis was made to determine the reliability of the model parameters. If the model with an exponential bulge profile is a reasonable description of a galaxy, the maximum errors in the derived model parameters are of order 20%. The uncertainties in the model parameters will increase, if
the exponential bulge function is replaced by other often used bulge functions as the de Vaucouleurs law. All decomposition methods were applied to the optical and near-infrared data set presented by de Jong & van der Kruit (1994), which comprises 86 galaxies in six passbands.
%K methods: data analysis - surveys - galaxies: fundamental parameters - galaxies: photometry - galaxies: spiral - galaxies: structure

%R 1996A&AS..118..575P
%J-585
%A Pantin E., Starck J.-L.
%T Deconvolution of astronomical images using the multiscale maximum entropy method.
%F 1996.08.05
%B Following the ideas of Bontekoe et al. who noticed that the classical Maximum Entropy Method (MEM) had difficulties to efficiently restore high and low spatial frequency structure in an image at the same time, we use the wavelet transform, a mathematical tool to decompose a signal into different frequency bands. We introduce the concept of multi-scale entropy of an image, leading to a better restoration at all spatial frequencies. This deconvolution method is flux
conservative and the use of a multiresolution support solves the problem of MEM to choose the {alpha} parameter, i.e. the relative weight between the goodness-of-fit and the entropy. We show that our algorithm is efficient too for filtering astronomical images. A range of practical examples illustrate this approach.
%K techniques: image processing

%R 1996A&AS..118..587J
%J-594
%A Jetsu L., Pelt J.
%T Searching for periodicity in weighted time point series.
%F 1996.08.05
%B Consistent statistics for two methods of searching for periodicity in a series of weighted time points are formulated. An approach based on the bootstrap method to estimate the accuracy of detected periodicity is presented.
%K methods: statistical; analytical

%R 1996A&AS..118..595V
%J-603
%A Valenti J.A., Piskunov N.
%T Spectroscopy made easy: A new tool for fitting observations with synthetic spectra.
%F 1996.08.05
%B We describe a new software package that may be used to determine stellar and atomic parameters by matching observed spectra with synthetic spectra generated from parameterized atmospheres. A nonlinear least squares algorithm is used to solve for any subset of allowed parameters, which include atomic data (log gf and van der Waals damping constants), model atmosphere specifications (T_ eff_, logg), elemental abundances, and radial, turbulent, and rotational velocities. LTE
synthesis software handles discontiguous spectral intervals and complex atomic blends. As a demonstration, we fit 26 FeI lines in the NSO Solar Atlas (Kurucz et al. 1984), determining various solar and atomic parameters.
%K radiative transfer - methods: numerical - techniques: spectroscopic - stars: fundamental parameters - sun: fundamental parameters - atomic data