A proper-motion study of the open cluster NGC 3680

Abstract

view Abstract Citations (56) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Proper-Motion Study of the Open Cluster NGC 3680 Kozhurina-Platais, Vera ; Girard, Terrence M. ; Platais, Imants ; van Altena, William F. ; Ianna, Phillip A. ; Cannon, Russell D. Abstract Relative proper motions and cluster membership probabilities have been determined for 2711 stars in a region containing the old open cluster NGC 3680. The Yale-Columbia 26 in. refractor plates used in this study contain significant magnitude equation as well as color equation. A procedure is developed for transforming the measures from each of the plates into a common magnitude/color equation system, thus yielding differential positions from plate to plate, (i.e., proper motions) which are free of these systematic errors. For well measured stars the mean standard error of the proper motions is +/- 0.35 mas/yr. Three different membership calculation techniques are described in detail. The best fit to the proper-motion distributions yields 74 cluster members. Almost all known red giants are cluster member according to the proper motion membership criterion. The luminosity function of NGC 3680 shows a characteristic turnover at Mupsilon approximately equals +3 mag and an essentially flat faint end. Monte-Carlo simulations are used in order to explore the mutual dependence of the luminosity function and membership probabilities. The bimodality of the upper main sequence found in earlier photometric studies probably still exists even after eliminating proper-motion nonmembers. Publication: The Astronomical Journal Pub Date: February 1995 DOI: 10.1086/117310 Bibcode: 1995AJ....109..672K Keywords: Color-Magnitude Diagram; Image Processing; Open Clusters; Radial Velocity; Stellar Motions; Astronomical Photometry; Monte Carlo Method; Red Giant Stars; Statistical Analysis; Stellar Color; Stellar Luminosity; Stellar Magnitude; Astronomy; OPEN CLUSTERS AND ASSOCIATIONS: INDIVIDUAL: NGC 3680 full text sources ADS | data products SIMBAD (2711) CDS (1) Related Materials (1) Catalog: 1995yCat.1212....0K