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Micrometer observations of double stars and new pairs. XIII
From a program of double star observations which emphasizes orbital,neglected, and newly discovered pairs, results obtained from October1984 to January 1987 are presented. A total of 3030 visual and 550photographic measures are listed. The positions in WDS format andDurchmusterung numbers are shown for 117 pairs for which firstobservations appear in this paper. Magnitudes are estimated for some ofthe objects.
| Hyades and Sirius supercluster members brighter than magnitude (V) 7.1. II - Right ascension six to twelve hours
The present star sample is contained in the Bright Star Catalogue andits Supplement, augmented with a further supplement of 788 stars foundduring various observing programs over the past 40 years. Accurate,four-color and H-beta, or (RI), photometry is available for most of thesupercluster members. The criteria for membership are the comparisons ofthe proper motion, radial velocity, and luminosity obtained from thesupercluster parameters with the observed motions and the luminosityderived from the photometric parameters. New proper motions, based onall available catalogs, have been derived for the additional 788 starsdiscussed here, as well as all supercluster members.
| Micrometer observations of double stars and new pairs. XII
Measurements of 2132 pairs and 103 double stars, obtained in both theNorthern and Southern Hemispheres in the period June 1982 to September1984, are listed in a table. The observations were carried out using theSwarthmore College 61-cm refractor, and the 100 and 91 cm telescopes ofthe Cerro Tololo Inter-American Observatory. Corrections to the IDScatalog (1961 version) are given for some of the fainter stars in thesurvey.
| The chemical evolution of the solar neighborhood. I - A bias-free reduction technique and data sample
The possible ways of measuring the age-metallicity relation for thegalactic disk in the neighborhood of the sun are discussed. It is shownthat the use of a field star sample chosen on the basis of effectivetemperature introduces a bias which results in a monotonic increase inthe metal abundance of the disk with time. However, if theage-metallicity relation for the disk can be shown to satisfy certaincriteria, the bias introduced in such a sample can be neglected: thegalactic disk apparently satisfies the criteria. It is concluded that asample analyzed through the use of uvby and H(beta) photometry inconjunction with a self-consistent set of theoretical isochronesprovides the least biased, most accurate estimate of the age-metallicityrelation for the disk.
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