LAMOST DR7中Be型星投影旋转速度的研究
Investigation of projected rotational velocities of Be-type stars in LAMOST DR7
AI总结：
研究利用傅里叶变换方法推导LAMOST DR7中479颗Be型星投影旋转速度，发现不同Hα发射线形态的Be型星速度分布不同，不同环境中无显著差异，样本反卷积速度分布非双峰，还研究了相关关系。
AI中文摘要：
恒星旋转在角动量转移中起关键作用，大量具有可靠投影旋转速度的Be型星样本对理解其形成和演化至关重要。本文基于LAMOST中分辨率光谱，用傅里叶变换方法推导479颗Be型星的投影旋转速度。结果表明该方法可通过分析特定谱线提供可靠值。不同Hα发射线形态的Be型星旋转速度分布不同，不同环境中的Be型星速度分布无显著差异。样本的反卷积速度分布非双峰，平均赤道旋转速度为临界速度的0.74倍。还研究了双峰Hα发射线Be型星速度与Hα峰分离速度的关系。
英文摘要：
Stellar rotation plays a key role in the transfer of angular momentum, and a large sample of Be-type stars with reliable projected rotational velocities is crucial for understanding their formation and evolution. In this work, we derive the projected rotational velocities ($v$\,sin\,$i$) of 479 Be-type stars using the Fourier transform method, based on their LAMOST Medium-resolution Survey (MRS) spectra. Our results suggest that the Fourier transform method can provide reliable $v$\,sin\,$i$ values for Be-type stars by analyzing the \ion{He}{1}\,lines at 4922, 5015, 5047, and 6678 \,Åin their LAMOST MRS spectra. A K-S test indicates that Be-type stars with different H$α$ emission line morphologies exhibit different $v$\,sin\,$i$ distributions, and Be-type stars with double-peaked emission have a higher fraction of rapid rotators than those with single-peak emission. The $v$\,sin\,$i$ distributions of our Be-type stars in the field, OB associations, and clusters show no significant differences. The deconvolved $v$\,sin\,$i$ distribution of our entire Be-type star sample does not exhibit a bimodal distribution but rather a single peak at $v\approx260$\,km$\cdot$s$^{-1}$. Based on the analysis of 105 stars in our sample, we find that the mean equatorial rotational velocity is 0.74 times the critical velocity. Furthermore, we investigate the relationship between $v$\,sin\,$i$ and the H$α$ peak separation velocity for Be-type stars exhibiting double-peak H$α$ emission lines, using Pearson and Spearman rank correlation coefficients.
