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arXiv 1012.3176astro-ph.CO
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旋涡星系的凸起和盘:边缘透视

Bulges and discs of spiral galaxies: edge-on perspective

N. Ya. Sotnikova, V. P. Reshetnikov, A. V. Mosenkov

摘要:

我们给出了一个边缘靠近旋涡星系的样本,包括175个KS滤波器星系、169个H滤波器星系和165个J滤波器星系。每个星系的图像,从两微米全天巡天(2 MASS)的凸起和光盘分解,进行。我们讨论了几个缩放关系的凸起和光盘,这表明它们的形成和演化之间的紧密联系。我们发现,星系的结构参数的分布与星系的星系的结构参数的分布有很大的不同,其中星系的球核的Sersic指数n<2(伪球核)与星系的球核的经典球核(经典球核)有很大的不同。首先,对于n<2的子样本,表观隆起轴比qb的分布可归因于三轴的、近长球形隆起,而n>=2的隆起似乎是具有中等扁平度的扁球体。其次,样品凸起的光度平面并不平坦,并且具有朝向较小n值的显著曲率。第三,尽管恒星盘的扁平度h/z_0与球形分量的相对质量之间存在着明显的关系,但这两个参数的分布对于具有球核和假球核的星系是完全不同的。

英文摘要:

We present a sample of edge-on spiral galaxies both of early and late types.The sample consists of 175 galaxies in the Ks-filter, 169 galaxies in the H-filter and 165 galaxies in the J-filter. Bulge and disc decompositions of each galaxy image, taken from the Two Micron All Sky Survey (2MASS), were performed. We discuss several scaling relations for bulges and discs which indicate a tight link between their formation and evolution. We show that galaxies with bulges fitted by the Sersic index n<2 (pseudobulges) have quite different distributions of their structural parameters than galaxies with n>=2 bulges (classical bulges). First of all, the distribution of the apparent bulge axis ratio q_b for the subsample with n<2 can be attributed to triaxial, nearly prolate bulges, while n>=2 bulges seem to be oblate spheroids with moderate flattening. Secondly, the Photometric Plane of the sample bulges is not flat and has a prominent curvature towards small values of n. Thirdly, despite of the existence of a clear relation between the flattening of stellar discs h/z_0 and the relative mass of a spherical component, the distributions over both parameters are quite different for galaxies possesing bulges and pseudobulges.

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