BATC 15 BAND PHOTOMETRY OF THE OPEN CLUSTER NGC 188
BATC 15 BAND PHOTOMETRY OF THE OPEN CLUSTER NGC 188
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DOI：
10.1088/0004-6256/150/2/61
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发表时间：
2015-06
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影响因子：
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通讯作者：
Jiaxing Wang;Jun Ma;Zhenyu Wu;Song-Yun Wang;Xu Zhou Key Laboratory of Optical Astronomy;National Astronomical Observat
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文献类型：
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作者：
Jiaxing Wang;Jun Ma;Zhenyu Wu;Song-Yun Wang;Xu Zhou Key Laboratory of Optical Astronomy;National Astronomical Observat
本文介绍了老疏散星团NGC 188的CCD测光。这些观测是作为北京-亚利桑那-台湾-康涅狄格多色巡天的一部分，从1995年2月到2008年3月，使用了15个覆盖3000-10000流明的中频滤波器。通过对Padova理论等时线的拟合，得到了该星系团的基本参数：年龄t = 7.5 ± 0.5？Gyr，距离模量（m-M）0 = 11.17 ± 0.08？>红化E（B − V）= 0.036 ± 0.010？> .利用星星计数得到了NGC 188的径向面密度分布。通过对King模型的拟合，导出了NGC 188的结构参数：核半径Rc = 380？，潮汐半径Rt = 4478？>浓度参数C 0 = log（Rt/Rc）= 1.07？.将质量函数（MF）拟合为幂律函数φ（m）<$m？>在此基础上，导出了不同空间区域的MFs的斜率。我们发现NGC 188在MF中呈现出一个斜坡突变。断裂质量为m break = 0.885 M m？> .在质量范围大于m break？>，整个区域的斜率为=-0.76？> .核心区坡度= 1.09？>，和外部区域的斜率=-0.86？> =-2.15？，分别。在质量范围低于m break？>，这些斜率为= 0.12？>，= 4.91？>，= 1.33？>，并且=-1.09？>，分别。NGC 188的质量分离反映在该星团不同空间区域的斜率变化上。
This paper presents CCD multicolor photometry for the old open cluster NGC 188. The observations were carried out as part of the Beijing–Arizona–Taiwan–Connecticut Multicolor Sky Survey from 1995 February to 2008 March, using 15 intermediate-band filters covering 3000–10000 Å. By fitting the Padova theoretical isochrones to our data, the fundamental parameters of this cluster are derived: an age of t = 7.5 ± 0.5 ?> Gyr, a distance modulus of ( m − M ) 0 = 11.17 ± 0.08 ?> , and a reddening of E ( B − V ) = 0.036 ± 0.010 ?> . The radial surface density profile of NGC 188 is obtained using the star count. By fitting the King model, the structural parameters of NGC 188 are derived: a core radius of R c = 3 80 ?> , a tidal radius of R t = 44 78 ?> , and a concentration parameter of C 0 = log ( R t / R c ) = 1.07 ?> . Fitting the mass function (MF) to a power-law function φ ( m ) ∝ m ?> , the slopes of the MFs for different spatial regions are derived. We find that NGC 188 presents a slope break in the MF. The break mass is m break = 0.885 M ⊙ ?> . In the mass range above m break ?> , the slope of the overall region is = − 0.76 ?> . The slope of the core region is = 1.09 ?> , and the slopes of the external regions are = − 0.86 ?> and = − 2.15 ?> , respectively. In the mass range below m break ?> , these slopes are = 0.12 ?> , = 4.91 ?> , = 1.33 ?> , and = − 1.09 ?> , respectively. The mass segregation in NGC 188 is reflected in the obvious variation of the slopes in different spatial regions of this cluster.