THE OPTICAL GRAVITATIONAL LENSING EXPERIMENT. VARIABLE STARS IN GLOBULAR CLUSTERS. IV. FIELDS 104A-E IN 47 TUCANAE
THE OPTICAL GRAVITATIONAL LENSING EXPERIMENT. VARIABLE STARS IN GLOBULAR CLUSTERS. IV. FIELDS 104A-E IN 47 TUCANAE
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DOI：
10.1051/aas:1998382
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发表时间：
1997-05
期刊：
影响因子：
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通讯作者：
J. Kaluzny;M. Kubiak;M. Szymański;A. Udalski;W. Krzemiński;M. Mateo;K. Stanek
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文献类型：
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作者：
J. Kaluzny;M. Kubiak;M. Szymański;A. Udalski;W. Krzemiński;M. Mateo;K. Stanek
位于球状星团NGC Tuc中心附近的五个区域被用来寻找变星。我们给出了42个变星的V波段光变曲线.这个样本包括13颗天琴座RR型恒星，其中12颗属于小麦哲伦星云（SMC），1颗是银河晕的背景天体。发现了12颗食双星，其中9颗是接触系统，3颗是分离/半分离系统。7个食双星位于星团色星等图（CMD）上的蓝离散星区域，4个双星可以被认为是主序星系统。一个二进制可能是SMC的成员。八个接触双星可能是星团的成员，其中一个很可能是前景星星。我们发现，在47 Tuc的调查区域，与最近调查的其他球状星团相比，接触双星的相对频率非常低。已识别变量的样本还包括15个红色变量，周期从约2天到数周不等。这15颗变星中的很大一部分可能属于SMC，但有几颗恒星可能是47 Tuc的红巨星。作为我们巡天的副产品，获得了来自星团视场的约50000颗恒星的VI测光。
Five fields located close to the center of the globular cluster NGC Tuc were surveyed in a search for variable stars. We present V -band light curves for 42 variables. This sample includes 13 RR Lyr stars – 12 of them belong to the Small Magellanic Cloud (SMC) and 1 is a background object from the galactic halo. Twelve eclipsing binaries were identified – 9 contact systems and 3 detached/semi-detached systems. Seven eclipsing binaries are located in the blue straggler region on the cluster color-magnitude diagram (CMD) and four binaries can be considered main-sequence systems. One binary is probably a member of the SMC. Eight contact binaries are likely members of the cluster and one is most probably a foreground star. We show that for the surveyed region of 47 Tuc, the relative frequency of contact binaries is very low as compared with other recently surveyed globular clusters. The sample of identified variables also includes 15 red variables with periods ranging from about 2 days to several weeks. A large fraction of these 15 variables probably belong to the SMC but a few stars are likely to be red giants in 47 Tuc. VI photometry for about 50 000 stars from the cluster fields was obtained as a by product of our survey.