An Ap star catalog based on LAMOST DR9

Abstract

We present a sample of 2700 Ap stars in LAMOST DR9. The candidates are first selected to be in a temperature range typical of Ap stars by using the $BP$-$RP$ color index from Gaia DR3. Then the 5200\,\AA\ flux depression features characteristic of Ap stars are visually checked in LAMOST DR9 spectra. The detailed spectral features are given by applying a modified spectral classification program, MKCLASS. Stellar parameters of these Ap stars such as $T_{\rm eff}$, $\log g$, [Fe/H], [Si/H], and $v{\sin}i$ are either extracted from a hot star catalog or derived through empirical relations and then a statistical analysis is carried out. The evolutionary stages are also discussed. Finally, we discuss the rotation and pulsation features of those who have TESS or Kepler light curves. Among these Ap stars we find 7 new rotation variables, 1 new roAp star, and new $\delta$ Scuti pulsation of a previously known roAp star.