论文标题
超热木星黄蜂中的硅酸盐云前体吸收紫外线
UV Absorption by Silicate Cloud Precursors in Ultra-hot Jupiter WASP-178b
论文作者
论文摘要
已经发现气溶胶在子宫大气中几乎无处不在。这些气溶胶在系外行星中开始形成的确切温度尚未受到观察。理论模型和观察到柔和的光谱特征表明，硅酸盐云在至少950至2,100 K之间的系外行星中起着重要作用。但是，某些巨型行星被认为足够热以避免完全凝结。在这里，我们介绍了超热木星的近紫外传输频谱，WASP-178B（$ \ sim $ 2,450〜K），显示出明显的NUV吸收。就大气尺度的高度而言，这种短波长的吸收是在系系外行星中观察到的最大光谱特征之一。贝叶斯检索表明存在含有硅和镁的气态难治物质，它们是在较低温度下凝结云的前体。特别是以前在系系群中没有检测到SIO，但是WASP-178b中SIO的存在与理论上的期望一致，因为在高温下，作为主要的SI含Si含Si含Si-Barearing物种。这些观察结果使我们能够重新解释对HAT-P-41B和WASP-121B的先前观察结果，这些观察结果不认为SIO暗示硅酸盐云形成始于平衡温度在1,950至2,450〜K之间的系外行星。
Aerosols have been found to be nearly ubiquitous in substellar atmospheres. The precise temperature at which these aerosols begin to form in exoplanets has yet to be observationally constrained. Theoretical models and observations of muted spectral features suggest that silicate clouds play an important role in exoplanets between at least 950 and 2,100 K. However, some giant planets are thought to be hot enough to avoid condensation altogether. Here, we present the near-UV transmission spectrum of an ultra-hot Jupiter, WASP-178b ($\sim$2,450~K), that exhibits significant NUV absorption. This short-wavelength absorption is among the largest spectral features ever observed in an exoplanet in terms of atmospheric scale heights. Bayesian retrievals indicate the presence of gaseous refractory species containing silicon and magnesium, which are the precursors to condensate clouds at lower temperatures. SiO in particular has not been detected in exoplanets before, but the presence of SiO in WASP-178b is consistent with theoretical expectation as the dominant Si-bearing species at high temperatures. These observations allow us to re-interpret previous observations of HAT-P-41b and WASP-121b that did not consider SiO to suggest that silicate cloud formation begins on exoplanets with equilibrium temperatures between 1,950 and 2,450~K.
