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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.
| SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
| A catalog of K giants at the South Galactic Pole - Broadband and DDO photometry and radial velocities
We describe a sample of K giants at the South Galactic Pole, selected toexamine the chemical and kinematical properties of stars perpendicularto the galactic plane and to measure the local column density of thedisk. We report velocities, abundances, absolute magnitudes, andbroadband BV photometry for over 500 giants.
| Local dark matter from a carefully selected sample
The precise data obtained by Flynn and Freeman (1991) on K giants at thesouth Galactic pole are used to analyze the amount of local dark matterin which the systematic effects can be modeled easily and evaluatedaccurately. The method of Bahcall (1984) is employed to solve theself-consistent equations for the distribution of dark matter. TheK-giant survey is found to provide significant evidence for disk darkmatter. Taking into account all recognized sources of error using astatistical test devised by Gould (1989, 1990), a model with no darkmatter is inconsistent with the data at the 86-percent confidence level.The best-fit P-model (in which dark matter is distributed proportionallyto known matter) has 53 percent more dark matter than visible matter.
| A kinematic and abundance survey at the galactic poles
The DDO intermediate band system is used to obtain detailed informationabout abundance gradients and velocity dispersions in the galaxy, withan emphasis on the properties of halo stars in the range of from 1 to 5kpc. The DDO abundance index is calibrated agianst (Fe/H) for metal-poorstars, with a resulting gradient of about -0.2 per kpc. However, whenthe sample is divided into two subsamples with (Fe/H) less than -0.5 andequal to or greater than -0.5, the gradients are -0.14 and 0.00,respectively. DDO observations of about 1000 stars, mostly G5-K5 giants,show that the velocity dispersion increases both with decrease inmetallicity and increase in z distance. The abundances found for high-zstars are similar to the A-star results of Rodgers (1971) in that abouthalf the K giants above 1 kpc appear to have solar abundances.
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| Takýmyýldýz: | Yontar |
| Sað Açýklýk: | 00h27m51.15s |
| Yükselim: | -25°16'54.6" |
| Görünürdeki Parlaklýk: | 8.636 |
| Uzaklýk: | 10000000 parsek |
| özdevim Sað Açýklýk: | 9.4 |
| özdevim Yükselim: | 10.7 |
| B-T magnitude: | 10.236 |
| V-T magnitude: | 8.769 |
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