We present a study of the structure and kinematics of the triple-shell planetary nebula NGC 7662 based on long-slit echelle spectroscopic observations and Hubble Space Telescope archival narrowband images. The structure of the main nebula consists of a central cavity surrounded by two concentric shells. The bright inner shell has a nonnegligible thickness and the highest density in the nebula. The outer shell is filled with nebular material whose density profile shows a ∝r-1 drop-off in the inner regions of the shell and flattens in the outermost regions. Both the inner and the outer shells can be described as prolate ellipsoids: the inner shell is more elongated, while the outermost layer of the outer shell expands faster. The physical structure of NGC 7662 is qualitatively consistent with the predictions of hydrodynamical simulations based on the interacting stellar wind models for planetary nebulae with a 0.605 M⊙ central star. Models with a higher asymptotic giant branch wind velocity are needed for detailed comparisons.
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机译：我们基于长缝埃切尔光谱观测和哈勃太空望远镜档案窄带图像，对三壳行星状星云NGC 7662的结构和运动学进行了研究。主星云的结构由被两个同心壳包围的中央空腔组成。明亮的内壳具有不可忽略的厚度，并且在星云中具有最高的密度。外壳填充有星状材料，其密度分布在壳的内部区域显示∝r-1下降，而在最外部的区域则变平。内壳和外壳体都可以描述为长椭球体：内壳体更细长，而外壳体的最外层膨胀得更快。 NGC 7662的物理结构在质量上与基于具有0.605M⊙中心恒星的行星状星云相互作用的恒星风模型的流体动力学模拟的预测一致。需要具有较高渐近巨分支风速的模型进行详细比较。
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