2026/07/09 by Zhicun Liu, Jiao Li, Jiaming Liu +4
Physics and Astronomy · #Stellar, planetary, and galactic studies #Astrophysics and Star Formation Studies #Astronomy and Astrophysical Research
paper · pdf · doi:10.3847/1538-4357/ae7713
Abstract 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 (FT) method, based on their Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium Resolution Survey (MRS) spectra. Our results suggest that the FT method can provide reliable v sin i values for Be-type stars by analyzing the He i lines at 4922, 5015, 5047, and 6678 Å in their LAMOST MRS spectra. A Kolmogorov–Smirnov 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-peaked 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 ≈ 260 km 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-peaked H α emission lines using Pearson and Spearman rank correlation coefficients.