Is NGC 7006 a globular cluster with a primarily red horizontal branch?

被引:0
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作者
A. N. Gerashchenko
机构
[1] Russian Academy of Sciences,Main (Pulkovo) Astronomical Observatory
来源
Astronomy Reports | 2007年 / 51卷
关键词
98.20.Gm; 95.85.Kr;
D O I
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中图分类号
学科分类号
摘要
A CCD BV R photometric study of the central region (15″ ≤ r ≤ 100″) of the globular cluster NGC 7006 based on color-magnitude diagrams is presented. We find for the main parameters of the cluster [Fe/H] = −1.62, Y = 0.21, EB−V = 0.15m, VHB = 18.84m, MVHB =+0.56m, R⊙ = 37.1 kpc). Two previously unknown RR Lyr variables were discovered in the central region of the cluster. The morphological index of the horizontal branch for the entire region studied indicates that the red stellar population dominates, consistent with previous studies: HBmi = −0.13. Such anomalously negative morphological indices are possessed by a whole group of Ool clusters with intermediate metallicities, which also display a characteristic distribution of stars along the horizontal branch. There is a radial dependence for the horizontal-branch morphology, with the color becoming primarily blue with approach toward the cluster center. One possible origin for this behavior could be the effect of inner dynamical processes on the spatial distribution of hot stars.
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页码:542 / 548
页数:6
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