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Long-term monitoring of active stars. X. Photometry collected in 1994
As part of an extensive program focused on the global properties andevolution of active stars, high-precision UBV(RI)_c and UBV photometryof 18 selected stars is presented. UBV(RI)_c observations were collectedat the European Southern Observatory over the intervals 21-28 September1994 and 25 November-05 December 1994. Additional UBV photometryobtained late in 1994 by Catania Astrophysical Observatory AutomaticPhotoelectric Telescope is also presented. Significant evolution of thelight curves, period variations and evidence for long-term variabilityof the global degree of spottedness are found. Some spectralclassifications are revised and photometric parallaxes are compared,whenever possible, with the values measured by the Hipparcos satellite.These observations are finalized to the construction of an extendedphotometric database, which can give important clues on topics such asthe stability of spotted areas, differential stellar rotation,solar-like activity cycles and the correlation between inhomogeneitiesat different atmospheric levels.Based on data collected at the European Southern Observatory, La Silla,Chile.Tables 1, 2 and 4 and the complete data set are only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/400/659 (Table 3 is alsoavailable at the CDS).
| Two-colour photometry for 9473 components of close Hipparcos double and multiple stars
Using observations obtained with the Tycho instrument of the ESAHipparcos satellite, a two-colour photometry is produced for componentsof more than 7 000 Hipparcos double and multiple stars with angularseparations 0.1 to 2.5 arcsec. We publish 9473 components of 5173systems with separations above 0.3 arcsec. The majority of them did nothave Tycho photometry in the Hipparcos catalogue. The magnitudes arederived in the Tycho B_T and V_T passbands, similar to the Johnsonpassbands. Photometrically resolved components of the binaries withstatistically significant trigonometric parallaxes can be put on an HRdiagram, the majority of them for the first time. Based on observationsmade with the ESA Hipparcos satellite.
| X-ray emission from the flare star binary Gliese 867 A
Coronal X-ray emission from the BY Draconis type dMe flare star G867 Awas observed on three successive days in May 1980 with the ImagingProportional Counter on the Einstein Observatory. A 40-percent decreasein the quiescent state X-ray intensity of the star was detected over athree-day period. It is suggested that this slow quiescent state X-rayintensity variation may be the X-ray analogue of the BY Draconisvariability observed in the optical band and may be explained by thestar spot model. The energy spectra of the star were obtained for thethree days and are best fitted by a two-temperature Raymond-Smiththermal model. There is some indication of spectral variations in thelow temperature component. Implications of these results are brieflydiscussed.
| Micrometer measures of doubles stars. III.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1963AJ.....68...57V&db_key=AST
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