EXOFAST: A Fast Exoplanetary Fitting Suite in IDL
EXOFAST: A Fast Exoplanetary Fitting Suite in IDL
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DOI：
10.1086/669497
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发表时间：
2012-06
影响因子：
3.5
通讯作者：
J. Eastman;-B.;S. Gaudi;E. Agol
中科院分区：
文献类型：
--
作者：
J. Eastman;-B.;S. Gaudi;E. Agol
我们介绍了EXOFAST，这是一套用IDL编写的快速、健壮的程序，旨在同时或分别拟合行星际凌日和径向速度变化，并用微分进化马尔科夫链蒙特卡罗方法表征参数的不确定性和协方差。我们描述了我们的代码如何结合这两个数据集来同时导出恒星参数以及中转和RV参数，从而在标准台式计算机上在不到5分钟的时间内很好地混合的HAT-P-3b发现数据的示例拟合上产生了更自洽的结果。我们详细描述了我们的代码是如何工作的，并概述了如何扩展代码以包括附加效果或概括其他数据集--包括非行星数据集--的特征。我们讨论了几种常用的偏心率参数化方法的优缺点，强调了MCMC实现中的一个细微错误，该错误可能会使推断的固有圆形轨道的偏心率偏离显著的非零结果，讨论了IDL内置随机数生成器应用于大型MCMC拟合的问题，并推导出一种解析拟合行星凌日的线性和二次肢体变暗系数的方法。最后，我们解释了如何提高精度，并将公交模型计算的执行时间提高了100倍以上。我们的全部源代码，以及我们的经纬仪和径向速度拟合的几个基本功能的易于使用的在线界面，都可以在http://astroutils.astronomy.ohio-state.edu/exofast.上在线获得
We present EXOFAST, a fast, robust suite of routines written in IDL that is designed to fit exoplanetary transits and radial velocity variations simultaneously or separately and characterize the parameter uncertainties and covariances with a differential evolution Markov chain Monte Carlo method. We describe how our code incorporates both data sets to derive simultaneously stellar parameters along with the transit and RV parameters, resulting in more self-consistent results on an example fit of the discovery data of HAT-P-3b that is well-mixed in under 5 minutes on a standard desktop computer. We describe in detail how our code works and outline ways in which the code can be extended to include additional effects or generalized for the characterization of other data sets—including non-planetary data sets. We discuss the pros and cons of several common ways to parameterize eccentricity, highlight a subtle mistake in the implementation of MCMC that could bias the inferred eccentricity of intrinsically circular orbits to significantly non-zero results, discuss a problem with IDL’s built-in random number generator in its application to large MCMC fits, and derive a method to analytically fit the linear and quadratic limb darkening coefficients of a planetary transit. Finally, we explain how we achieved improved accuracy and over a factor of 100 improvement in the execution time of the transit model calculation. Our entire source code, along with an easy-to-use online interface for several basic features of our transit and radial velocity fitting, are available online at http://astroutils.astronomy.ohio-state.edu/exofast.