Detection of magnetic fields in chemically peculiar stars observed with the K2 space mission

TL;DR

This study combines spectropolarimetry and space photometry to detect and analyze magnetic fields and pulsations in chemically peculiar stars, revealing new magnetic detections and pulsation signatures relevant for magneto-asteroseismology.

Contribution

It provides new magnetic field detections in chemically peculiar stars and links pulsation phenomena with magnetic properties using combined observational techniques.

Findings

11 stars confirmed with large-scale magnetic fields, 9 are new detections.

2 stars show roAp pulsations, 1 shows gravity waves or g-mode pulsations.

5 stars likely host weak magnetic fields despite non-detections.

Abstract

We report the results of an observational study aimed at searching for magnetic pulsating hot stars suitable for magneto-asteroseismology. A sample of sixteen chemically peculiar stars was selected and analysed using both high-resolution spectropolarimetry with ESPaDOnS and K2 high-precision space photometry. For all stars, we derive the effective temperature, surface gravity, rotational and non-rotational line broadening from our spectropolarimetric data. High-quality K2 light curves were obtained for thirteen of the sixteen stars and revealed rotational modulation, providing accurate rotation periods. Two stars show evidence for roAp pulsations, and one star shows signatures of internal gravity waves or unresolved g-mode pulsations. We confirm the presence of a large-scale magnetic field for eleven of the studied stars, of which nine are first detections. Further, we report one marginal detection and four non-detections. Two of the stars with a non-detected magnetic field show rotational modulation due to surface abundance inhomogeneities in the K2 light curve, and we confirm that the other two are chemically peculiar. Thus, these five stars likely host a weak (undetected) large-scale magnetic field.