标题： 原行星状星云和年轻行星状星云中的不对称性和非均匀性 显示英文标题

标题： Asymmetry and Inhomogeneity in Proto and Young Planetary Nebulae

摘要： 我研究了渐近巨星分支（AGB）末阶段非球对称物质损失对原行星 nebulae (PNs) 和年轻 PNs 外观的一些影响。 非球对称物质损失可以是小尺度的不均匀性，和/或轴对称的质量损失几何结构。 我首先检查了光学波段尘埃消光在原行星 nebulae 外观中的作用。 我得出结论，那些源自具有高赤道物质损失率的 AGB 恒星的原行星 nebulae 将会拥有大的光学深度，这需要一个伴星的存在。 这些原行星 nebulae 将变成双极行星 nebulae，即具有两个瓣和它们之间赤道腰部的行星 nebulae，或者是极端椭圆形的行星 nebulae。 然后我推导了早期行星 nebulae 阶段电离前沿传播增强非径向密度不均匀性的条件。 电离将在低密度区域沿径向更快地进行。 低密度区域将更早被加热，并由于更高的压力而膨胀，进一步降低其密度。 相反，在高密度区域会发生相反的情况。 显示英文摘要

摘要： I study some effects of aspherical mass loss during the last stages of the asymptotic giant branch (AGB) on the appearance of proto planetary nebulae (PNs) and young PNs. The aspherical mass loss can be small scale inhomogeneities, and/or axially symmetric mass loss geometry. I first examine the role of the dust opacity in the optical band on the appearance of proto-PNs. I conclude that large optical depth will be found in proto-PNs which are descendant of AGB stars having high equatorial mass loss rates, which require a stellar binary companion for their existence. These proto-PNs will become bipolar-PNs, i.e., PNs with two lobes an an equatorial waist between them, or extreme elliptical PNs. I then derive the conditions for the enhancement of non-radial density inhomogeneity by the propagation of the ionization front at the early PN stages. The ionization will proceed faster in the radial direction along low density regions. The low density regions will be heated earlier, and they will expand due to their higher pressures, reducing further their densities. The opposite occurs in high density regions.