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arXiv 1107.5601astro-ph.SR
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半人马座ω星水平分支星的特殊性质

The peculiar properties of horizontal branch stars in omega Centauri

Christian Moni Bidin, Sandro Villanova, Giampaolo Piotto, Sabine Moehler, Francesca D'Antona

摘要:

我们测量的温度,重力和质量的大样本的蓝色水平分支恒星在半人马座欧米茄,比较结果与理论预期的典型和氦丰富的恒星,并与以前的测量在其他三个集群。测得的ω Cen恒星的重力系统低于规范模型,与对He富集恒星的预期一致,而与在比较星团中观察到的相反。然而,导出的质量也不切实际地过低。这不能仅仅用低重力来解释,也不能用计算中输入的任何其他参数来解释。我们发现,相同的恒星并不比其他星团中的类似物更亮,这与氦富集情景的预期相反。因此,对结果的解释并不简单,但它们揭示了欧米茄Cen中的HB星与三个比较星团中的HB星之间内在的物理差异。

英文摘要:

We measured temperatures, gravities, and masses for a large sample of blue horizontal branch stars in omega Centauri, comparing the results with theoretical expectations for canonical and He-enriched stars, and with previous measurements in three other clusters. The measured gravities of omega Cen stars are systematically lower than canonical models, in agreement with expectations for He-enriched stars, and contrary to that observed in the comparison clusters. However, the derived masses are unrealistically too low as well. This cannot be explained by low gravities alone, nor by any of the other parameters entering in the calculation. We find that the same stars are not brighter than their analogs in the other clusters, contrary to the expectations of the He-enrichment scenario. The interpretation of the results is thus not straightforward, but they reveal an intrinsic, physical difference between HB stars in omega Cen and in the three comparison clusters.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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