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arXiv 0909.0448astro-ph.SR
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环状星云SuWt 2的动力学

Kinematics of the ring-like nebula SuWt 2

D. Jones, M. Lloyd, D. L. Mitchell, D. L. Pollacco, T. J. O'Brien, N. M. H. Vaytet

摘要:

我们提出了第一个详细的空间运动学分析和建模的南方行星状星云SuWt 2。这个天体对目前行星状星云形成和演化的理论提出了一个问题,因为它不知道是否包含一颗中央的后主序星。深窄带[NII]6584图像揭示了从星云环边缘发出的微弱双极叶的存在。H-α和[NII]6584发射线的长缝观测是在3.6-m ESO-NTT上使用EMMI获得的。光谱显示星云的形态是一个明亮的环面,环绕着一个扩展的双极结构的腰部。通过解投影,发现环的倾角为68 $\degr$ $\pm$ 2 $\degr$(参见图11)。~90 $\degr$的双A型联星被认为是在星云的中心),环膨胀速度被发现是28公里/秒。我们的研究结果进行了讨论,与可能的形成场景SuWt 2。通过比较星云的日心系统速度(-25 $\pm$ 5 km/s)和双A型双星的日心系统速度,我们得出结论,双星的两个组成部分都不可能是星云的祖先。然而,我们不能排除该系统的第三个组成部分的存在,这将是星云的祖先。

英文摘要:

We present the first detailed spatio-kinematical analysis and modelling of the Southern planetary nebula SuWt 2. This object presents a problem for current theories of planetary nebula formation and evolution, as it is not known to contain a central post-main sequence star. Deep narrowband [NII]6584 images reveal the presence of faint bipolar lobes emanating fromthe edges of the nebular ring. Longslit observations of the H-alpha and [NII]6584 emission lines were obtained using EMMI on the 3.6-m ESO-NTT. The spectra reveal the nebular morphology as a bright torus encircling the waist of an extended bipolar structure. By deprojection, the inclination of the ring is found to be 68$\degr$ $\pm$ 2$\degr$ (c.f. ~90$\degr$ for the double A-type binary believed to lie at the centre of the nebula), and the ring expansion velocity is found to be 28 km/s. Our findings are discussed with relation to possible formation scenarios for SuWt 2. Through comparison of the nebular heliocentric systemic velocity, found here to be -25 $\pm$ 5 km/s, and the heliocentric systemic velocity of the double A-type binary, we conclude that neither component of the binary could have been the nebular progenitor. However, we are unable to rule out the presence of a third component to the system, which would have been the nebula progenitor.

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