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

TL;DR

This study demonstrates that Gaia BP/RP low-resolution spectra can effectively identify magnetic chemically peculiar stars by detecting their characteristic 520 nm flux depression, enabling large-scale searches in extensive stellar databases.

Contribution

The paper introduces a method to detect mCP stars using Gaia BP/RP spectra, achieving high detection rates and facilitating large-scale identification of these stars.

Findings

Detection rate of ~95% for B- and A-type mCP stars.

Detection efficiency decreases for cooler stars, consistent with flux depression models.

Gaia BP/RP spectra are suitable for large-scale mCP star searches.

Abstract

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. 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. We employed the tool of Delta a 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. 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. The BP/RP spectra are clearly qualified to efficiently search for and detect mCP stars.