Title: Very Thin Disc Galaxies in The SDSS Catalog of Edge-on Galaxies Show Chinese title

Title: 非常薄盘星系在SDSS边缘星系目录中

Abstract: We study the properties of galaxies with very thin discs using a sample of 85 objects whose stellar disc radial-to-vertical scale ratio determined from photometric decomposition, exceeds nine. We present evidences of similarities between the very thin disc galaxies (VTD galaxies) and low surface brightness (LSB) disc galaxies, and conclude that both small and giant LSB galaxies may reveal themselves as VTD, edge-on galaxies. Our VTD galaxies are mostly bulgeless, and those with large radial scale length tend to have redder colors. We performed spectral observations of 22 VTD galaxies with the Dual Imaging Spectrograph on the 3.5m telescope at the Apache Point Observatory. The spectra with good resolution (R ~ 5000) allow us to determine the distance and the ionized gas rotation curve maximum for the galaxies. Our VTD galaxies have low dust content, in contrast to regular disc galaxies. Apparently, VTD galaxies reside in specific cosmological low-density environments and tend to have less connection with filaments. Comparing a toy model that assumes marginally low star formation in galactic discs with obtained gas kinematics data, we conclude that there is a threshold central surface density of about 88 Mo/pc**2, which we observe in the case of very thin, rotationally supported galactic discs. Show Chinese abstract

Abstract: 我们研究了使用85个天体样本中具有非常薄盘的星系的特性，这些天体的恒星盘径向与垂直尺度比通过光度分解确定，超过九。 我们提供了非常薄盘星系（VTD星系）和低表面亮度（LSB）盘星系之间相似性的证据，并得出结论，认为小型和巨型LSB星系可能表现为VTD星系，即边缘朝向我们的星系。 我们的VTD星系大多没有核球，那些具有较大径向尺度长度的星系往往颜色更红。 我们对22个VTD星系进行了光谱观测，使用的是Apache Point Observatory 3.5米望远镜上的双成像光谱仪。 高分辨率（R ~ 5000）的光谱使我们能够确定星系的距离和电离气体旋转曲线的最大值。 我们的VTD星系含尘量较低，这与普通盘星系形成对比。 显然，VTD星系位于特定的宇宙低密度环境中，且与丝状结构的联系较少。 将一个假设银河盘中勉强低恒星形成率的玩具模型与获得的气体动力学数据进行比较，我们得出结论，存在大约88 Mo/pc**2的中心表面密度阈值，我们在非常薄、旋转支持的银河盘的情况下观察到了这一阈值。