NEW PROPER MOTIONS IN THE GLOBULAR-CLUSTER M92

被引:31
作者
REES, RF
机构
[1] Yerkes Observatory, University of Chicago, Williams Bay, WI 53191
关键词
D O I
10.1086/116170
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
New proper motions have been obtained from reductions of PDS microdensitometer scans of 22 Yerkes refractor plates over an epoch range of 88 yr for 365 stars down to V approximately 16 in the region of the globular cluster M92. These scans, combined with scans of eight Yerkes reflector plates, have also yielded photographic photometry of these stars. The errors in the new proper motions are smaller than those in the previous Yerkes study of M92 [Cudworth, AJ, 81, 975 (1976b)] by factors of 2-3. Membership probabilities derived from the new proper motions are largely in agreement with Cudworth's earlier probabilities, but since this study covers a larger number of stars, additional highly probable cluster members are presented. A color-magnitude diagram of probable members is presented and discussed, as is evidence of systematic errors in previous photographic photometry. All previously known or suspected variables included in this study, with the exception of V14, are highly probable members. A search for previously unknown variables reveals some possible but no definite candidates. A preliminary astrometric distance of 8.3 +/- 1.6 kpc is derived, consistent with other distance determinations. A new space velocity is also derived from the proper motions.
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收藏
页码:1573 / 1582
页数:10
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