Early-type star stellar rotations in LAMOST MRS. I.

The primary selection of our early-type sample was obtained from LAMOST Data Release 7 based on spectral-line indices. We employed the Stellar Label Machine to derive their spectroscopic stellar parameters, drawing on Kurucz spectral synthesis models with 6000<Teff<15000K and -1<[M/H]<1dex.

For a signal-to-noise ratio of ~60, the cross validated scatter is ~75K, 0.06dex, 0.05dex, and ~3.5km/s for Teff, logg, [M/H], and vsini, respectively. A comparison with objects with prior known stellar labels shows great consistency for all stellar parameters, except for logg. Although this is an intrinsic caveat that comes from the MRS's narrow wavelength coverage, it only has a minor effect on estimates of the stellar rotation rates because of the decent spectral resolution and the profile-fitting method employed.