在BeSOS数据库中通过傅立叶变换获得$v \sin i$值的自动算法
Automatic algorithm to obtain $v \sin i$ values via Fourier Transform in BeSOS database
摘要：
Be星的自转接近于临界自转，因此被认为是研究恒星自转的重要实验室。在这种情况下，我们得到的投影旋转速度的样本的经典Be南方星在BeSOS数据库中通过傅立叶变换在自动化的方式在不同的时期的几个吸收线。对观测到的8条He I光球谱线拟合高斯分布，自动选取95.45%、98.75%和99.83%曲线下面积的谱线信号，通过傅里叶变换得到$v \sin i$。得到的值是在全球协议与文献。仅分析一条线路不足以设置$v \sin i$值，取决于线路，在大多数情况下，相对于$λ$ 4471，该值被低估。当包括重力暗化效应时，表观值增加$\sim10$ %。用于BeSOS光谱（$R \sim 17\,000$）的仪器PUCHEROS的分辨率限制了可能在$v \sin i \sim 100$ km s $^{-1}$的理论下限。对于旋转速度接近于分裂速度的经典Be星，如果没有重力暗化修正，则使用带有$\varepsilon = 0.6$的线性边缘暗化函数，该方法有其不可忽略的局限性。以前的作品测量$v \ sin i$值只使用一个光谱线，在这里，我们证明，与更多的线的结果可能会有所不同。这可能是由于在经典Be星上原子跃迁的光球分布。
英文摘要：
Be stars are found to rotate close to their critical rotation and therefore they are considered as an important laboratory of study for stellar rotation. In this context, we obtain the projected rotational velocity of a sample of classical Be Southern stars in the BeSOS database via Fourier Transform in an automated way for several absorption lines at different epochs. A Gaussian profile is fitted to eight observed photospheric HeI lines in order to select automatically the spectral signal given by areas under the curve of 95.45%, 98.75% and 99.83% from the profile to obtain $v \sin i$ via Fourier Transform technique. The values obtained are in global agreement with the literature. Analysing only one line is not enough to set the $v \sin i$ value, depending on the line the value in most cases are underestimated with respect to $λ$4471. When gravity darkening effects are including, apparent values increases by $\sim10$%. The resolution of the instrument PUCHEROS used for BeSOS spectra ($R \sim 17\,000$) constrain a theoretical lower bound possible at $v \sin i \sim 100$ km s$^{-1}$. The procedure has limitations using a linear limb-darkening function with $\varepsilon = 0.6$ for classical Be stars rotating close to the break-up velocity without gravity-darkening corrections, which can't be negligible. Previous works measure $v \ sin i$ values using just one spectral line and here we demonstrate that with more lines the results can varies. This could be due to the photospheric distribution of atomic transitions on classical Be stars.
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