The detection of magnetic chemically peculiar stars using Gaia BP/RP spectra

Abstract

Context. The magnetic chemically peculiar (mCP) stars of the upper main sequence are perfectly suited to studying the effects of rotation, diffusion, mass-loss, accretion, and pulsation in the presence of an organized stellar magnetic field. Therefore, many important models can only be tested with this star group.
Aims: In this case study we investigate the possibility of detecting the characteristic 520 nm flux depression of mCP stars using low-resolution BP/RP spectra of the Gaia mission. This would enable us to effectively search for these objects in the ever-increasing database.
Methods: We employed the tool of Δa photometry to trace the 520 nm flux depression for 1240 known mCP and 387 normal-type objects including binaries. To this end, we folded the filter curves with the BP/RP spectra and generated the well-established color-color diagram.
Results: It is clearly possible to distinguish mCP stars from normal-type objects. The detection rate is almost 95% for B- and A-type objects. It then drops for cooler-type stars, which is in line with models of the 520 nm flux depression.
Conclusions: The BP/RP spectra are clearly qualified to efficiently search for and detect mCP stars.