论文标题
跟踪与TIO化学的超级元素大气中的散装元素比率
Tracing bulk elemental ratios in exoplanetary atmospheres with TiO chemistry
论文作者
论文摘要
知道超级行星氛围的大元素丰度并不是一件容易的事，但是了解行星的形成历史至关重要。这项工作的目的是表明，在热木星气氛的传输光谱中，TIO特征在光波长处的可观察性对大气的庞大化学特性敏感。为此，我们运行了一个化学模型的网格，其中包括TIO形成和破坏，用于超热的木星黄蜂-19B和HD〜209458B的超热版本。我们考虑了由不同的C/O比引起的这些大气的温度和压力结构的非平衡化学和压力结构的变化。我们为这些模型计算合成传输光谱，并在定量上研究TIO和\ CE {H2O}特征的相对强度。为了与观测值进行比较，我们使用一个独立的度量标准来分子丰度，$Δz_{\ rm tio-h_2o}/h _ {\ rm eq} $以前已用于外生体氛围的观察性研究。我们发现，通过这种度量，我们可以区分不同的化学模型，并在大气的大块碳和氧气丰度上放置约束。从化学考虑因素来看，我们期望TIO丰度取决于大量氮，但是发现对N/H的任何变化都不会导致所得TIO的变化。我们将我们的方法应用于相关光波长中已经观察到的一组已知系外行星，并在低分辨率观测值和我们的WASP-121B模型之间找到了良好的一致性，与WASP-79B，WASP-76B和WASP-76B和WASP-19B和WASP-19B和与HD 209458B一致的模型，与WASP-79B，WASP-76B和差异很差。我们的方法对于对碳和氧气的大量丰度的间接研究特别有用。
Knowing the bulk elemental abundances of an exoplanetary atmosphere is not an easy task, but it is crucial to understand the formation history of planets. The purpose of this work is to show that the observability of TiO features at optical wavelengths in the transmission spectra of hot Jupiter atmospheres is sensitive to the bulk chemical properties of the atmosphere. For that, we run a grid of chemical models which include TiO formation and destruction, for the ultra-hot Jupiter WASP-19b and an ultra-hot version of HD~209458b. We take into account non-equilibrium chemistry and changes in the temperature and pressure structure of these atmospheres caused by different C/O ratios. We calculate synthetic transmission spectra for these models, and study the relative strengths of TiO and \ce{H2O} features quantitatively. To compare with observations, we use a model independent metric for molecular abundances, $ΔZ_{\rm TiO-H_2O}/H_{\rm eq}$ that has been previously used in observational studies of exoplanetary atmospheres. We find that with this metric we can differentiate between different chemical models and place constraints on the atmosphere's bulk carbon and oxygen abundance. From chemical considerations we expected that the TiO abundance would depend on the bulk nitrogen, however found that any change to N/H did not result in changes to the resulting TiO. We apply our method to a set of known exoplanets that have been observed in the relevant optical wavelengths and find good agreement between low resolution observations and our model for WASP-121b, marginally good agreement with WASP-79b, WASP-76b, and WASP-19b, and poorer agreement with HD 209458b. Our method can be particularly helpful for indirect studies of the bulk abundances of carbon and oxygen.
