HELIOS: AN OPEN-SOURCE, GPU-ACCELERATED RADIATIVE TRANSFER CODE FOR SELF-CONSISTENT EXOPLANETARY ATMOSPHERES
HELIOS: AN OPEN-SOURCE, GPU-ACCELERATED RADIATIVE TRANSFER CODE FOR SELF-CONSISTENT EXOPLANETARY ATMOSPHERES
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DOI：
10.3847/1538-3881/153/2/56
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发表时间：
2016-06
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通讯作者：
M. Malik;Luc Grosheintz;J. Mendonça;S. Grimm;B. Lavie;D. Kitzmann;Shang-min Tsai;A. Burrows;L. Kreidberg;M. Bedell;J. Bean;K. Stevenson;K. Heng
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作者：
M. Malik;Luc Grosheintz;J. Mendonça;S. Grimm;B. Lavie;D. Kitzmann;Shang-min Tsai;A. Burrows;L. Kreidberg;M. Bedell;J. Bean;K. Stevenson;K. Heng
我们介绍了一个开源的辐射传输程序HELIOS，它是为研究行星际大气而构建的。在其初始版本中，HELIOS的模式大气是一维的平面平行的，辐射传输方程在非各向同性散射的双流近似下求解。使用了一小部分主要的红外吸收体，用不透明度计算器HELIOS-K计算，并使用关联k近似进行组合。分子丰度来源于经过验证的平衡化学分析公式。我们使用GJ 1214b模式将HELIOS与Miller-Ricci&Fortney的工作进行了比较，并进行了几次测试，结果发现：具有单温层的模式大气努力收敛到辐射平衡；在不透明度函数中使用cm−1分辨率(每波数箱的点数)构造的k-分布表可能导致合成光谱的误差%-10%；在纯吸收极限下，扩散系数2很好地逼近精确的辐射传递解。我们建立了六颗热木星的“零假设”模型(化学平衡、辐射平衡和太阳元素丰度)。我们发现HD 189733b和WASP-43b的日侧发射光谱与零假设一致，而后者始终低估了WASP-8b、WASP-12b、WASP-14b和WASP-33b的观测通量。我们证明，我们的结果对恒星模型(黑体、Kurucz或菲尼克斯)和金属丰度的选择不太敏感，但受到较高的碳氧比的强烈影响。该代码作为ExoClimate es模拟平台(exoClimate e.net)的一部分公开提供。
We present the open-source radiative transfer code named HELIOS, which is constructed for studying exoplanetary atmospheres. In its initial version, the model atmospheres of HELIOS are one-dimensional and plane-parallel, and the equation of radiative transfer is solved in the two-stream approximation with nonisotropic scattering. A small set of the main infrared absorbers is employed, computed with the opacity calculator HELIOS-K and combined using a correlated-k approximation. The molecular abundances originate from validated analytical formulae for equilibrium chemistry. We compare HELIOS with the work of Miller-Ricci & Fortney using a model of GJ 1214b, and perform several tests, where we find: model atmospheres with single-temperature layers struggle to converge to radiative equilibrium; k-distribution tables constructed with cm−1 resolution in the opacity function ( points per wavenumber bin) may result in errors %–10% in the synthetic spectra; and a diffusivity factor of 2 approximates well the exact radiative transfer solution in the limit of pure absorption. We construct “null-hypothesis” models (chemical equilibrium, radiative equilibrium, and solar elemental abundances) for six hot Jupiters. We find that the dayside emission spectra of HD 189733b and WASP-43b are consistent with the null hypothesis, while the latter consistently underpredicts the observed fluxes of WASP-8b, WASP-12b, WASP-14b, and WASP-33b. We demonstrate that our results are somewhat insensitive to the choice of stellar models (blackbody, Kurucz, or PHOENIX) and metallicity, but are strongly affected by higher carbon-to-oxygen ratios. The code is publicly available as part of the Exoclimes Simulation Platform (exoclime.net).