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HD 135692


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New periodic variables from the Hipparcos epoch photometry
Two selection statistics are used to extract new candidate periodicvariables from the epoch photometry of the Hipparcos catalogue. Theprimary selection criterion is a signal-to-noise ratio. The dependenceof this statistic on the number of observations is calibrated usingabout 30000 randomly permuted Hipparcos data sets. A significance levelof 0.1 per cent is used to extract a first batch of candidate variables.The second criterion requires that the optimal frequency be unaffectedif the data are de-trended by low-order polynomials. We find 2675 newcandidate periodic variables, of which the majority (2082) are from theHipparcos`unsolved' variables. Potential problems with theinterpretation of the data (e.g. aliasing) are discussed.

Five-colour photometry of early-type stars in the direction of galactic X-ray sources
The results of five-color (Walraven system) photometry of 551 O- andB-type stars located in 17 fields of a few square degrees aroundgalactic X-ray sources are presented. From a comparison ofreddening-free combinations of color indices with theoretical values,calculated for model atmospheres of Kurucz (1979), effective temperatureand surface gravity for these stars are derived. In addition theirabsolute magnitude are determined by combining these parameters with theresults of evolutionary calculations of massive stars. These effectivetemperatures are in good agreement with the temperature scale ofBohm-Vitense (1981) for stars of luminosity classes II to V. For thesupergiants the effective temperatures are about 40 percent higher. Forstars of luminosity classes III to V the absolute magnitudes agree wellwith the results of independent luminosity calibrations of spectraltypes, but for brighter stars they deviate systematically. Thephotometric data are also used to study the interstellar reddening inthe direction of the X-ray sources.

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Pozíciós és asztrometriai adatok

Csillagkép:Körző
Rektaszcenzió:15h19m22.04s
Deklináció:-60°22'30.7"
Vizuális fényesség:7.857
Távolság:961.538 parszek
RA sajátmozgás:-8.6
Dec sajátmozgás:-7.4
B-T magnitude:7.878
V-T magnitude:7.859

Katalógusok és elnevezések:
Megfelelő nevek
HD 1989HD 135692
TYCHO-2 2000TYC 9021-1153-1
USNO-A2.0USNO-A2 0225-22309671
HIPHIP 74983

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