用新的多相模型模拟微温Corinos中碳链物种的形成
Modelling carbon-chain species formation in lukewarm corinos with new multi-phase models
摘要：
在不冷不热的Corinos L1527、B228和L483中观察到了丰富的碳链物种。这些碳链物种被认为是在30 K左右的温度下CH $_4$从尘埃颗粒表面解吸后在气相中合成的。我们调查碳链物种形成在微温corinos使用更严格的数值方法和先进的表面化学模型。我们使用宏观蒙特卡罗方法进行模拟。除了两相模型，基本的多相模型和新的多相模型用于模拟尘埃颗粒的表面化学。在两相模型中，所有挥发性物质都可以在其升华温度下升华，而在基本和新的多相模型中，大多数挥发性物质在水冰升华之前被冻结在冰幔中。新的多相模型允许更多的挥发性物种升华在他们的升华温度比基本的多相模型。当T $\sim$ 30 K时，两相模型中CH $_4$和CO的丰度最高，而基本多相模型中CO和CH $_4$的丰度最低。当T $\sim$ 30 K时，基本模型和新模型中碳链物种的丰度均低于两相模型，这是因为CH $_4$是合成碳链物种的关键.两相模型在预测碳链物种丰度以拟合观测值方面表现最好，而基本多相模型的效果最差。新的多相模型预测的碳链物种的丰度与观测结果相当吻合。CH $_4$的数量可以在冰幔内扩散，因此在升温时升华，在气相中碳链物种的合成中起着至关重要的作用。在不冷不热的科里诺斯中观察到的碳链物种可能能够测量表面化学模型。
英文摘要：
Abundant carbon-chain species have been observed towards lukewarm corinos L1527, B228, and L483. These carbon-chain species are believed to be synthesized in the gas phase after CH$_4$ desorbs from the dust grain surface at the temperature around 30 K. We investigate carbon-chain species formation in lukewarm corinos using a more rigorous numerical method and advanced surface chemical models. We use the macroscopic Monte Carlo method in simulations. In addition to the two-phase model, the basic multiphase model and the new multiphase models are used for modeling surface chemistry on dust grains. All volatile species can sublime at their sublimation temperatures in the two-phase model while most volatile species are frozen in the ice mantle before water ice sublimes in the basic and the new multiphase models. The new multiphase models allow more volatile species to sublime at their sublimation temperatures than the basic multiphase model does. When T $\sim$ 30 K, the abundances of gaseous CH$_4$ and CO in the two-phase model are the highest while the basic multiphase model predicts the lowest CO and CH$_4$ abundances among all models. The abundances of carbon-chain species in the basic and the new multiphase models are lower than that in the two-phase model when T $\sim$ 30 K because CH$_4$ is crucial for the synthesis of carbon-chain species. The two-phase model performs the best to predict carbon-chain species abundances to fit observations while the basic multiphase model works the worst. The abundances of carbon-chain species predicted by the new multiphase models agree reasonably well with observations. The amount of CH$_4$ that can diffuse inside the ice mantle, thus sublime upon warm-up plays a crucial role in the synthesis of carbon-chain species in the gas phase. The carbon-chain species observed in lukewarm corinos may be able to gauge surface chemical models.
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