The interplay between AGB interiors and their outermost layers, where molecules and dust form, is a problem of high complexity. As a consequence, physical processes like mass loss, which depend on the chemistry of the circumstellar envelope, are often oversimplified. The best candidates to drive mass-loss in AGB stars are dust grains, which trap the outgoing radiation and drag the surrounding gas. Grains build up, however, is far from being completely understood. Our aim is to model both the physics and the chemistry of the cool expanding layers around AGB stars in order to characterize the on-going chemistry, from atoms to dust grains. This has been our rationale to develop ab initio VULCAN, a FORTRAN hydro code able to follow the propagation of shocks in the circumstellar envelopes of AGB stars. The version presented in this paper adopts a perfect gas law and a very simplified treatment of the radiative transfer effects and dust nucleation. In this paper, we present preliminary results obtained with our code.

中文翻译：

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AGB星星及其绕星信封。I. VULCAN代码

AGB内部及其最外层（分子和灰尘在其中形成）之间的相互作用是一个高度复杂的问题。结果，像质量损失这样的物理过程通常会被简化，而这些过程取决于星际包膜的化学性质。引起AGB恒星质量损失的最佳人选是尘粒，它们会捕获发出的辐射并拖动周围的气体。但是，谷物的积累远未完全被理解。我们的目的是对AGB恒星周围的冷膨胀层的物理和化学模型进行建模，以表征从原子到尘埃粒子的持续化学过程。这就是我们从头开始的理由VULCAN是一种FORTRAN水电代码，它能够追踪激波在AGB恒星的星际包络中的传播。本文介绍的版本采用了完美的气体定律，并且对辐射传递效应和粉尘成核进行了非常简化的处理。在本文中，我们介绍了通过我们的代码获得的初步结果。