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Title: WIYN OPEN CLUSTER STUDY. LV. ASTROMETRY AND MEMBERSHIP IN NGC 6819

We present proper motions and astrometric membership analysis for 15,750 stars around the intermediate-age open cluster NGC 6819. The accuracy of relative proper motions for well-measured stars ranges from {approx}0.2 mas yr{sup -1} within 10' of the cluster center to 1.1 mas yr{sup -1} outside this radius. In the proper motion vector-point diagram, the separation between the cluster members and field stars is convincing down to V {approx} 18 and within 10' from the cluster center. The formal sum of membership probabilities indicates a total of {approx}2500 cluster members down to V {approx} 22. We confirm the cluster membership of several variable stars, including some eclipsing binaries. The estimated absolute proper motion of NGC 6819 is {mu}{sub x}{sup abs}=-2.6{+-}0.5 and {mu}{sub y}{sup abs}=-4.2{+-}0.5 mas yr{sup -1}. A cross-identification between the proper motion catalog and a list of X-ray sources in the field of NGC 6819 resulted in a number of new likely optical counterparts, including a candidate CV. For the first time we show that there is significant differential reddening toward NGC 6819.
Authors:
 [1] ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6]
  1. Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
  2. Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706 (United States)
  3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  5. Canada-France-Hawaii Telescope Corporation, Kamuela, HI 96743 (United States)
  6. Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States)
Publication Date:
OSTI Identifier:
22122882
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 146; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; ECLIPSE; GALAXY CLUSTERS; PROBABILITY; PROPER MOTION; VARIABLE STARS; X-RAY SOURCES