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arXiv 0910.0757astro-ph.COastro-ph.GA
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棒星系中的环和螺旋。II。环状和螺旋状形态

Rings and spirals in barred galaxies. II. Ring and spiral morphology

E. Athanassoula, M. Romero-Gomez, A. Bosma, J. J. Masdemont

摘要:

在这一系列的论文中,我们提出了一个理论来解释的形成和性质的环和螺旋的棒星系。这些结构的构建块是由位于杆的端部附近的不稳定拉格朗日点发出的流形引导的轨道。在本文中,我们专注于观察到的和理论的螺旋和环的形态的比较,我们也给出了一些进一步的比较预测。我们的理论可以解释螺旋以及内环和外环。模型外圈具有观察到的$R_1$、$R_1'$、$R_2$、$R_2'$和$R_1R_2$形貌,包括靠近棒长轴方向的凹坑。我们解释了为什么绝大多数的螺旋棒星系是两个武装和尾随,并讨论了需要更高的多重性武器的形式。我们发现,观察到的和理论上的螺旋形状一致,我们预测,更强的非轴对称强迫和超越共转将驱动更多的开放螺旋。我们比较了理论和观测中的环直径比,并预测更多的椭圆环将对应于更强的强迫。我们发现,模型势可能会强烈影响这些比值的数值。

英文摘要:

In this series of papers, we propose a theory to explain the formation and properties of rings and spirals in barred galaxies. The building blocks of these structures are orbits guided by the manifolds emanating from the unstable Lagrangian points located near the ends of the bar. In this paper we focus on a comparison of the morphology of observed and of theoretical spirals and rings and we also give some predictions for further comparisons. Our theory can account for spirals as well as both inner and outer rings. The model outer rings have the observed $R_1$, $R_1'$, $R_2$, $R_2'$ and $R_1R_2$ morphologies, including the dimples near the direction of the bar major axis. We explain why the vast majority of spirals in barred galaxies are two armed and trailing, and discuss what it would take for higher multiplicity arms to form. We show that the shapes of observed and theoretical spirals agree and we predict that stronger non-axisymmetric forcings at and somewhat beyond corotation will drive more open spirals. We compare the ratio of ring diameters in theory and in observations and predict that more elliptical rings will correspond to stronger forcings. We find that the model potential may influence strongly the numerical values of these ratios.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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