The Rotation of Blue Horizontal Branch Stars

天文学家使用“H-R图”（表面温度与温度的关系）。 恒星团的光度）来推断 恒星的年龄和化学丰度。 十多年前，人们注意到， 恒星沿着球状星团的“水平分支” 一部分取决于化学物质的丰度， 别的 这个“别的东西”可能是什么， 星团研究中的“第二参数问题”。 在早期NSF支持的工作中，首席研究员（PI） 令大多数天文学家惊讶的是， 分支恒星旋转得相当快。 PI将检查 八个球状星团水平星的自转速率 以确定旋转是否是缺失的参数。 此外，PI的早期工作使理论天文学家 表明中等质量核的旋转速率 在恒星的生命周期中，恒星可能会继续保持高位， 在它们表面的速率由于 它们的日冕中有磁场 新作品有望测试 这种可能性，并提供了为数不多的推断 目前在“主序星”上的恒星的内部自转速率。" 这些内部利率是无法以其他方式获得我们的直接 测量.

Astronomers use the "H-R Diagram" (surface temperature vs. luminosity) of stellar clusters to infer the evolutionary properties of stars of a common age and chemical abundance. Over a decade ago it was noticed that the distribution of stars along the "horizontal branch" of globular clusters depends in part on chemical abundance and in part on something else. What this "something else" might be constitutes the "second parameter problem" in the study of stellar clusters. In earlier NSF-supported work the Principal Investigator (PI) has found, to the surprise of most astronomers, that horizontal branch stars rotate rather rapidly. The PI will examine the rotation rates of horizontal stars in eight globular clusters to determine whether rotation is the missing parameter. In addition, the PI's earlier work led theoretical astronomers to suggest that the rotation rates of cores of intermediate mass stars may continue to remain high during the stars' lifetimes while the rates at their surfaces decelerate from the influence of magnetic fields in their coronae. The new work is expected to test this possibility and to offer one of the few ways of inferring the interior rotation rates of stars currently on the "main sequence." These interior rates are otherwise inaccessible to our direct measurement.