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|Spectroscopic and Photometric Observations of the Short-Period RS CVn-Type Star UV Piscium|
High-resolution spectroscopic observations around the Hα line andlong-term BVRI photometry of the eclipsing short-period RS CVn star UVPsc are presented. The simultaneous solution of our radial velocitycurves and light curves yields the following values for the globalparameters of the components: M1=1.1 Msolar,M2=0.81 Msolar, R1=1.14Rsolar, and R2=0.85 Rsolar. Themeasured rotational broadening of the spectral lines corresponds toequatorial velocities V1=68.3 and V2=53.3 kms-1. Our spectral data reveal high activity of the twostellar components and very fast variability of the Hα line in thecenter of the primary eclipse. Modeling our photometric data showstrends in the starspot behavior. The trend toward active longitude beltscan have occasional exceptions. The observed secular luminosity decreasein 1999 may signal the onset of a new magnetic activity cycle.
|Long-term monitoring of active stars. IX. Photometry collected in 1993|
As a part of an extensive program focused on the global properties andevolution of active stars, high-precision UBV(RI)_c and UBV photometryof 31 selected stars is presented. The UBV(RI)_c observations werecollected at the European Southern Observatory over the 31 December1992-18 January 1993 and the 20 November-3 December 1993 intervals.Additional UBV photometry obtained by the ``Phoenix" and by the CataniaAstrophysical Observatory Automatic Photoelectric Telescopes from 1990to 1993 is also presented for some of the program stars. Significantevolution of the light curves, period variations and evidence forlong-term variability of the global degree of spottedness are found.Some spectral classifications are revised and the inferred photometricparallaxes are compared, whenever possible, with the values measured bythe Hipparcos satellite. These observations are finalized to theconstruction of an extended photometric database, which can giveimportant clues on topics such as the stability of spotted areas,differential rotation, solar-like cycles and the correlation betweeninhomogeneities at different atmospheric levels. Based on data collectedat the European Southern Observatory, La Silla, Chile. Tables and thecomplete data set are also available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/367/910
|Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.|
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
|Long-term monitoring of active stars. IV. UBV(RI)_c_ observations obtained at La Silla in December 1989.|
High-precision UBV(RI)_c_ photometry of 23 selected acitve stars,collected at the European Southern Observatory (La Silla, Chile) overthe period 9-28 December 1989, is presented. This paper is part of alarger program focusing on the global properties and evolution of activestars and is aimed at establishing a time-extended database which cangive important clues on topics such as the stability of the spottedareas, differential rotation and solar-like cycles. Significantevolution of the wave-like light curves, period variations and, in mostcases, evidence for long-term variability of the global degree ofspottedness are found for the observed stars. Some spectralclassifications are rediscussed and evidence for a newly discoveredvariable star is given.
|Photometry of Stars in the Field of Nova Cassiopeiae 1993|
|Evolved GK stars near the sun. I - The old disk population|
A sample of nearly two thousand GK giants with intermediate band, (R,I),DDO and Geneva photometry has been assembled. Astrometric data is alsoavailable for most of the stars. The some 800 members of the old diskpopulation in the sample yield accurate luminosities (from two sources),reddening values and chemical abundances from calibrations of thephotometric parameters. Less than one percent of the objects arepeculiar in the sense that the flux distribution is abnormal. Thepeculiarity is signaled by strong CH (and Ba II) and weak CH. The CH+stars are all spectroscopic binaries, probably with white dwarfcompanions, whereas the CH- stars are not. A broad absorption band,centered near 3500 A, is found in the CH+ stars whereas the CH- objectshave a broad emission feature in the same region. The intensity of theseabsorptions and emissions are independent of the intensity of abnormalspectral features. Ten percent of the old disk sample have a heavyelement abundance from one and a half to three times the solar value.The distribution of the heavy element abundances is nearly a normal onewith a peak near solar abundance and ranges three times to one sixthsolar. The distribution of the (U, V) velocities is independent of theheavy element abundance and does not appear to be random. Ten percent ofthe old disk stars show a CN anomaly, equally divided between CN strongand CN weak. Several stars of individual astrometric or astrophysicalimportance are isolated.
|UBVRI observations of southern hemisphere active stars. II - 1987 data|
Results are presented on high-precision UBV (RI)c photometricobservations of 13 southern-hemisphere RS CVn, BY Dra, and FK Com-typevariable stars, carried out in December 1987 at the European SouthernObservatory at La Silla (Chile). Compared with previous observations,significant changes of the light curves were detected, both in amplitudeand shape.
|Large and kinematically unbiased samples of G- and K-type stars. IV - Evolved stars of the old disk population|
Modified Stromgren and (R,I) photometry, along with DDO and Genevaphotometry, are presented for a complete sample of evolved old-disk Gand K giants in the Bright Star Catalogue. Stars with ages of between1.5 x 10 to the 9th and 10 to the 10th yr are found to have anear-normal distribution of heavy element abundances, centered on anFe/H abundance ratio of -0.1 dex. The old disk clusters NGC 3680 and IC4651 contain red-straggler young-disk giants that are probablycontemporaries of the blue stragglers in the clusters.
|Large and kinematically unbiased samples of G- and K-type stars. II - Observations of evolved stars in the Bright Star sample. III - Evolved young disk stars in the Bright Star sample|
Four color and RI observations were obtained for a large sample ofG-type and K-type stars in the Bright Star Catalogue. Data are firstpresented for 110 evolved stars. Photometry of evolved young diskpopulation stars have then been calibrated for luminosity, reddening,and metallicity on the basis of results for members of the Hyades andSirius superclusters. New DDO results are given for 120 stars.
|Photometric variability in chromospherically active stars. III - The binary stars|
Differential UBV photometry of 49 late-type chromospherically activebinary stars has been obtained. A total of 12,353 differential UBVmagnitudes have been acquired and are used to determine seasonalphotometric periods, amplitudes, mean brightnesses, maximum spotamplitudes, 'unspotted' differential magnitudes, and times of minimumlight. Standard Fourier techniques are used to investigate the cause ofthe light variability. Eight stars are found which exhibit lightvariations due not to spot activity but rather to ellipticity and/orreflection effect. Others show combinations of all three effects. Someof the systems also show substantial differences between theirrotational and orbital period.
|Photometric parameters of the comet Kohoutek 1973f|
On the basis of the author's own photoelectric measurements and those ofother authors, the photometric parameters of the comet Kohoutek 1973fwere derived. The authors used their own graphical method to reduce theobservations; this enables one to transform the observations, obtainedat different focal diaphragms, to any diaphragm and, thus, also to anylinear diameter of the comet. The photometric parametersmzero and n were computed for 5 selected intervals and for alinear diameter of the inner coma of 40.000 km. The relation betweenthese parameters was determined. The parameter n varies little with thedistance of the comet from the sun, and the comet did not display suddenchanges of brightness in the interval of observation.
|Catalog of Indidual Radial Velocities, 0h-12h, Measured by Astronomers of the Mount Wilson Observatory|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJS...19..387A&db_key=AST
|A Very Young Cluster with a Moderate Metal Deficiency|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970ApJ...161..159E&db_key=AST
|UBV photometry of 550 F, G and K type stars|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1966MNRAS.133..475A&db_key=AST
|Beobachtung der partiellen Sonnenfinsternis am 2 Oktober 1959.|