标题： M3和M13球状星团亮支的不同特征 显示英文标题

标题： Different Characteristics of the Bright Branches of the Globular Clusters M3 and M13

摘要： 我们利用配备有2K CCD的BOAO 1.8米望远镜，对球状星团M3和M13进行了宽视场BVI CCD测光观测。 我们展示了M3和M13的CMD图。 我们发现在V = 14.85处M3有AGB隆起，在V = 14.25处M13有AGB隆起。 发现M3中的AGB恒星更集中于隆起附近，而M13中的AGB恒星则沿AGB序列分散。 我们在V = 15.50处识别出M3的RGB隆起，在V = 14.80处识别出M13的RGB隆起。 我们估计了M3和M13的R和R2比率，并发现M3的R比M13的大，而当仅使用正常HB星时，M3和M13的R2相似。 然而，当我们把所有HB星都包括在内时，发现M3和M13的R相似，而M3的R2比M13的大。 我们将M3和M13的观测RGBLF与Bergbusch & VandenBerg在同一径向距离上的理论RGBLF进行了比较。 在比较M13的观测RGBLF和Bergbusch & VandenBerg的理论RGBLF时，我们发现了属于M13的“额外恒星”。 在Buzzoni等人对R的原始定义中，N(HB)对应于RR Lyrae不稳定带在log T_eff = 3.85处的HB星寿命。 因此，在仅包含正常HB星的情况下，M13的R值比M3的小，这可能部分是由“额外恒星”造成的；而在包含所有HB星的情况下，M3和M13的R相似，这可能是由于M13上部RGB中的“额外恒星”造成的。 如果M13上部RGB中的“额外恒星”是由有效的“深混合”引起的，这些事实支持了这样一个观点，即有效的“深混合”可能导致M3和M13之间以及后续序列的不同HB形态。 显示英文摘要

摘要： We carried out wide-field BVI CCD photometric observations of the GCs M3 and M13 using the BOAO 1.8 m telescope equipped with a 2K CCD. We present CMDs of M3 and M13. We have found AGB bumps at V = 14.85 for M3 at V = 14.25 for M13. It is found that AGB stars in M3 are more concentrated near the bump, while those in M13 are scattered along the AGB sequence. We identified the RGB bump of M3 at V = 15.50 and that of M13 at V = 14.80. We have estimated the ratios R and R2 for M3 and M13 and found that of R for M3 is larger than that for M13 while R2's for M3 and M13 are similar when only normal HB stars are used in R and R2 for M13. However, we found that R's for M3 and M13 are similar while R2 for M3 is larger than that for M13 when all the HB stars are included in R and R2 for M13. We have compared the observed RGB LFs of M3 and M13 with the theoretical RGB LF of Bergbusch & VandenBerg at the same radial distances from the cluster centers as used in R and R2 for M3 and M13. We found "extra stars" belonging to M13 in the comparison of the observed RGB LF of M13 and the theoretical RGB LF of Bergbusch & VandenBerg. In the original definition of R of Buzzoni et al., N(HB) corresponds to the lifetime of HB stars in the RR Lyrae instability strip at log T_eff = 3.85. So, the smaller R value resulting for M13 compared with that for M3 in the case where only normal HB stars are included in R and R2 for M13 may be partially caused by "extra stars", and the similar R's for M3 and M13 in the case where the all HB stars are included in R and R2 for M13 may be caused by "extra stars" in the upper RGB of M13. If "extra stars" in the upper RGB of M13 are caused by an effective "deep mixing" these facts support the contention that an effective "deep mixing" could lead to different HB morphologies between M3 and M13 and subsequent sequences.