文章基本信息

标题：A Search for Extra-tidal RR Lyrae in Globular Clusters NGC 5024 and NGC 5053
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作者：Chow-Choong Ngeow ; Justin Belecki ; Rick Burruss 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2020
卷号：160
期号：1
页码：1-15
DOI：10.3847/1538-3881/ab930b
语种：English
出版社：American Institute of Physics
摘要：Recently, Kundu et al. reported that the globular cluster NGC 5024 (M53) possesses five extra-tidal RR Lyrae. In fact, four of them were instead known members of a nearby globular cluster NGC 5053. The status of the remaining extra-tidal RR Lyrae is controversial depending on the adopted tidal radius of NGC 5024. We have also searched for additional extra-tidal RR Lyrae within an area of ~8 deg2 covering both globular clusters. This includes other known RR Lyrae within the search area, as well as stars that fall within the expected range of magnitudes and colors for RR Lyrae (and yet outside the cutoff of two-thirds of the tidal radii of each globular cluster for something to be called extra-tidal) if they were extra-tidal RR Lyrae candidates for NGC 5024 or NGC 5053. Based on the the proper-motion information and their locations on the color–magnitude diagram, none of the known RR Lyrae belong to the extra-tidal RR Lyrae of either globular clusters. In the cases where the stars satisfied the magnitude and color ranges of RR Lyrae, analysis of time series data taken from the Zwicky Transient Facility do not reveal periodicities, suggesting that none of these stars are RR Lyrae. We conclude that there are no extra-tidal RR Lyrae associated with either NGC 5024 or NGC 5053 located within our search area.
关键词：Globular star clusters (656);RR Lyrae variable stars (1410);Tidal tails (1701);Sky surveys (1464)