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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.
| Population studies. IV - The Rose 'red horizontal branch' candidates as probes of the thick disk
DDO observations are reported for 10 of the Upgren (1962) red giantswhich Rose (1985) has identified as red horizontal branch (RHB) stars ofa globular cluster type population in the Gilmore-Reid thick disk. It isshown here that, while in the final analysis Rose's hypothesis may becorrect, it is not unique, and that his RHB candidates have all thecharacteristics of clump stars in the old, metal-deficient, open clusterNGC 2243. The only way to test Rose's hypothesis in an unambiguous wayis to analyze a complete sample of stars having colors in the range B-Vbetween 0.7 and 0.95, rather than one chosen by spectral-type criteria.
| Search for light variations of HD 101065.
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