前主序星比我们想象的要老吗？
Are pre-main-sequence stars older than we thought?
摘要：
我们拟合了年轻星团和星协中零龄主序和末龄主序之间恒星的色星等图。我们得出的年龄是一个因素1.5到2比通常使用的年龄为这些地区，这是来自前主序星的位置在颜色星等图。通过对主序和前主序模型中的不确定性的考察，我们得出结论，较长的年龄尺度可能是正确的，这意味着我们必须向上修正年轻星团和星协的常用年龄。这样的修正可以解释原行星盘的观测寿命与行星形成时间的理论计算之间的差异。这也可以解释为什么没有年龄在500万年到3000万年之间的星团。我们使用的$τ^2$统计量，以适应主序列的数据，但发现，我们必须作出重大修改，如果我们要适应序列中有垂直段的颜色幅度图。我们提出了这种修改以及改进的方法计算拟合优度统计和参数的不确定性。实现本文所述方法的软件可从http://www.astro.ex.ac.uk/people/timn/tau-squared/获得
英文摘要：
We fit the colour-magnitude diagrams of stars between the zero-age main-sequence and terminal-age main sequence in young clusters and associations. The ages we derive are a factor 1.5 to 2 longer than the commonly used ages for these regions, which are derived from the positions of pre-main-sequence stars in colour-magnitude diagrams. From an examination of the uncertainties in the main-sequence and pre-main-sequence models, we conclude that the longer age scale is probably the correct one, which implies we must revise upwards the commonly used ages for young clusters and associations. Such a revision would explain the discrepancy between the observational lifetimes of proto-planetary discs and theoretical calculations of the time to form planets. It would also explain the absence of clusters with ages between 5 and 30Myr. We use the $τ^2$ statistic to fit the main-sequence data, but find that we must make significant modifications if we are to fit sequences which have vertical segments in the colour-magnitude diagram. We present this modification along with improvements to methods of calculating the goodness-of-fit statistic and parameter uncertainties. Software implementing the methods described in this paper is available from http://www.astro.ex.ac.uk/people/timn/tau-squared/
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。
