An Atmospheric Retrieval of the Brown Dwarf Gliese 229B
An Atmospheric Retrieval of the Brown Dwarf Gliese 229B
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DOI：
10.3847/1538-4357/ac9cc9
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发表时间：
2022-10
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影响因子：
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通讯作者：
Emily Calamari;J. Faherty;B. Burningham;Eileen C. Gonzales;Daniella C. Bardalez-Gagliuffi;J. Vos;M. Gemma;Niall Whiteford;Josefine Gaarn
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作者：
Emily Calamari;J. Faherty;B. Burningham;Eileen C. Gonzales;Daniella C. Bardalez-Gagliuffi;J. Vos;M. Gemma;Niall Whiteford;Josefine Gaarn
我们展示了使用布鲁斯特反演代码对 GL 229B 进行大气反演分析的结果。我们发现最适合的模型是无云的，这与 Line 等人的 T 矮星反演工作一致；扎莱斯基等人。和冈萨雷斯等人。从我们的模型确定的基本参数（质量、半径、log(L Bol /L Sun)、log(g)）与 SED 导出值的误差在 1σ 范围内，但 T eff 除外，我们检索到的 T eff 比基于进化模型的 SED 值冷大约 100 K。我们发现检索到的质量为 50−9+12 M Jup ，但是，我们还发现 Gl 229B 的可观测值可以通过无云模型来解释，该模型的质量先验为动态值 70 M Jup 。我们能够限制 H2O、CO、CH4、NH3、Na 和 K 的丰度，并找到与其初级 Gl 229A 相比的超太阳 C/O 比。我们报告了由于大气中氧气消耗而导致的整体太阳下金属丰度，但发现了与主星相匹配的太阳[C/H]。我们发现这项工作促进了超太阳 C/O 比率的基于检索的研究（特别是对于棕矮星）的增长趋势，并讨论了这一结果对形成机制和内部物理过程以及模型偏差的影响。
We present results from an atmospheric retrieval analysis of Gl 229B using the Brewster retrieval code. We find the best fit model to be cloud-free, consistent with the T dwarf retrieval work of Line et al.; Zalesky et al. and Gonzales et al. Fundamental parameters (mass, radius, log(L Bol /L Sun), log(g)) determined from our model agree within 1σ to SED-derived values, except for T eff where our retrieved T eff is approximately 100 K cooler than the evolutionary model-based SED value. We find a retrieved mass of 50−9+12 M Jup, however, we also find that the observables of Gl 229B can be explained by a cloud-free model with a prior on mass at the dynamical value, 70 M Jup . We are able to constrain abundances for H2O, CO, CH4, NH3, Na and K and find a supersolar C/O ratio as compared to its primary, Gl 229A. We report an overall subsolar metallicity due to atmospheric oxygen depletion, but find a solar [C/H], which matches that of the primary. We find that this work contributes to a growing trend in retrieval-based studies, particularly for brown dwarfs, toward supersolar C/O ratios and discuss the implications of this result on formation mechanisms and internal physical processes, as well as model biases.