Decreasing Systematic Errors in Estimates of Stellar Ages

天体物理学中比较困难的问题之一是确定恒星的年龄。我们可以测量恒星的质量和大小。我们可以知道它有多热，它是用什么做的。但是要想弄清楚一颗恒星的年龄，我们要依靠计算机模型。恒星模型可能非常不确定；建立模型需要我们估计我们无法实际测量的参数。星震学是通过测量恒星表面脉动的方式来研究恒星的。像太阳这样的恒星是脉动的，而恒星脉动的频率携带着关于恒星内部的信息。恒星地震数据将被用来改进恒星模型的基本参数，从而获得更可靠的年龄估计。这些结果将对包括太阳系外行星研究在内的广泛的其他天文学课题具有重要意义。该课程将为学生提供具有广泛技术和商业应用的数据分析、统计和计算方法技术方面的培训。恒星年龄的估计受到不确定性的影响，因为在建立模型之前，需要选择不能根据第一原理确定的参数。自由参数中最重要的是混合长度参数和初始氦丰度。次要参数包括过冲。这项调查的目的是利用星震数据来约束模型参数。恒星地震数据将被用来确定混合长度参数是否以及如何随着恒星参数，特别是金属丰度的变化而变化。对初始氦丰度也会做同样的事情。这些结果将被用来构建改进的等时线。还将利用地震数据研究岩心超调的特征。相关的理论研究将调查由对流模拟确定的熵-(金属丰度、有效温度、表面重力)关系是否与由地震数据确定的混合长度参数相匹配。

One of the more difficult problems in astrophysics is determining how old a star is. We can measure the mass of a star and how big it is. We can find out how hot it is and what it is made of. But to find out how old a star is, we rely on computer models. Stellar models can be very uncertain; making models requires us to estimate parameters that we are unable to actually measure. Asteroseismology is the study of stars by measuring the way their surfaces pulsate. Stars like the Sun pulsate, and the frequencies of stellar pulsation carry information about the interior of the star. Asteroseismic data will be used to refine the basic parameters of stellar models and thereby obtain more reliable age estimates. These results will be important for a wide range of other astronomical topics, including studies of extrasolar planets. This program will provide student training in techniques of data analysis, statistics, and computational methods that have a wide range of technical and commercial applications. Estimates of stellar ages suffer from uncertainties, because parameters that cannot be determined from first principles need to be chosen before models can be constructed. The most important among the free parameters are the mixing length parameter and the initial helium abundance. Secondary parameters include overshoot. The aim of this investigation is to use asteroseismic data to constrain model parameters. Asteroseismic data will be used to determine whether and how the mixing length parameter varies as a function of stellar parameters, in particular with metallicity. The same will be done for the the initial helium abundance. These results will then be used to construct improved isochrones. The signature of core-overshoot will also be studied using seismic data. A related theoretical investigation will investigate whether the entropy-(metallicity, effective temperature, surface gravity) relationships determined from convection simulations match the mixing-length parameter determined with seismic data.